The Patrick Moore Practical Astronomy Series

Series Editor

Gerald R. Hubbell

Mark Slade Remote Observatory, Locust Grove, VA, USA

More information about this series at http://​www.​springer.​com/​series/​3192

Gregory I. Redfern

Cruise Ship Astronomy and Astrophotography

Gregory I. Redfern

NASA JPL Solar System Ambassador, Ruckersville, VA, USA

ISSN 1431-9756e-ISSN 2197-6562

The Patrick Moore Practical Astronomy Series

ISBN 978-3-030-00957-1e-ISBN 978-3-030-00958-8

https://doi.org/10.1007/978-3-030-00958-8

Library of Congress Control Number: 2018960832

© Springer Nature Switzerland AG 2018

This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed.

The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use.

The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

This Springer imprint is published by the registered company Springer Nature Switzerland AG

The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland

Thank you Laurie, Rachel, and Daniel

for letting me roam the seas

and explore the stars.

Preface

Ahoy, shipmate!

If you are reading this book, you must be interested in taking a cruise AND including astronomy -astrophotography as part of your voyage, or at least thinking about it. I have been fortunate to be a Special Interest Lecturer on astronomy and space for Azamara Club Voyages, Cunard , Holland America Lines, Oceania Cruises , Regent Seven Seas Cruises, Royal Caribbean International, SeaDream Yacht Club, and Windstar Cruises Line .

In the dozens of voyages and tens of thousands of guests I have had the pleasure to sail and interact with, I have learned much about what cruise ship guests are interested in when it comes to learning about astronomy and astrophotography at sea. Cruise Ship Astronomy and Astrophotography at Sea is the culmination of those seagoing experiences coupled with five decades of studying, observing, photographing, educating, and lecturing on the universe.

It is very gratifying that many of the guests who have attended the lectures found a new interest in astronomy and/or astrophotography, while some were motivated to pick it up again, having lost contact with their passion for the stars . Conducting night sky viewing sessions for the guests also helped to jump-start or rekindle their interest in the stars.

On the educational side, when people discover how the stars are born, live, and die, they never look at the night sky the same way again. Learning about their home galaxy, the Milky Way , lends a warm familiarity to that ghostly glow they see in the dark sky at sea, realizing that it is our home in the universe at large. Perhaps their greatest discovery comes when they realize that everything they touch, smell, and see is only 5% of the observable universe . Oh, and for good measure, astronomers think there may be more than one universe! There will be much to ponder in this book.

An all too common comment after presenting “So, You Want To Be an Astrophotographer,” which is always the first lecture presented on each cruise, is, “I didn’t know you could do that. I never thought of it.” Seeing the images taken by first-time astrophotographers who take up the challenge of photographing the sky at sea as well as their being so full of pride at having done so – some with tears in their eyes – provided the motivation to bring this book to you.

The primary goal of this book is to provide practical information to readers on how to enjoy a cruise with an astronomy-astrophotography element included. The book is written so it can appeal to someone who has never cruised before or had any astronomy-astrophotography background. In doing so, each following chapter will take you step by step on how to go about enjoying this very satisfying and unique aspect of a cruise. Highlighted safety tips , ship tips, and photo tips will be provided where applicable to focus your attention on the very practical advice they provide.

A secondary goal is to take what you learn at sea and apply it to other water and ashore venues. Much of what you learn and experience at sea with regard to observing and photographing the sky carries over to other locations and opportunities that present themselves.

In case you find that you want to delve deeper into astronomy and astrophotography, which is a very distinct possibility, this book will help you get started. You may even get to the point where perhaps you want to upgrade your camera, lenses and associated accessories, computer software for imaging and astronomy, and maybe even the purchase of a telescope . It is all covered.

At the end of the book, there is a Suggested Reading and Internet Sites section that will have for each of the forthcoming chapters suggested books and Internet links for you to refer to that provide supplemental information to the topics in the chapter. This will be of great value to you when reading about the numerous astronomical and astrophotography topics.

The book has two parts to provide needed concentration on their respective subject matter. Part I, Cruise Ship Astronomy , is about the basics in cruise selection, packing, useful astronomical knowledge in a broad context supplemented by specific topical chapters on what to see in the sky, and most important of all, how to get the most out of your ship observatory during your cruise.

Chapter 1 , “ Cruise Considerations and What to Pack Astronomy-Wise,” discusses what you might want to consider in selecting a cruise line and available destinations. For instance, do you want a large ship or a small ship with their accompanying passenger capacity? How many days and of course nights at sea will the voyage encompass?

Looking at the published itinerary for a voyage, which tells you how long the cruise is, where the ship will be going, costs involved, and in some cases the shore excursions available, will provide crucial information. Here is a big consideration for your cruise selection criteria: Are there any astronomy-themed shore excursions that are part of your cruise? If there are world-renowned astronomically themed attractions such as ancient Mayan astronomical ruins, Stonehenge, Kennedy Space Center, and the observatories atop Mauna Kea in Hawaii, they may be listed as shore excursions offered by the ship. Using the itinerary, you can also conduct online research that might reveal observatories, historical landmarks, planetariums, universities, museums, and archaeological or geological features with an astronomical theme located at each port of call .

Now that you have your cruise picked out and have an idea of what you want to do, what to pack? Every cruiser is always mindful of what goes into the luggage due to airline baggage/weight limitations as well as the limited closet/storage space aboard ship – especially if there are two of you sharing a stateroom . There are some astronomy-astrophotography essentials to take with you, but the good news is that they do not take up much space and are not very expensive to purchase. A suggested list of what to pack is provided, and each item is highlighted as to its intended use – astronomy and/or astrophotography.

It is recommended that the list be followed for your first cruise to make sure you have the necessary basics. As you gain more at-sea time and experience, you can modify what you pack according to your requirements. A detailed packing list for your camera gear, which of course is dependent on what kind of camera you will use, is covered later in the book.

Cruise selected, check. Bags packed, check. Countdown to embarkation date aboard ship, started. Now is the time to learn a little bit about astronomy and the universe we live in. Much of what is in Chap. 2 , “ Big Bang to Homo Erectus to Multi-Messenger Astronomy ,” comes from my lectures, public outreach for NASA, and college astronomy classes. We will go back to where astronomers think it all started, some 13.82 billion years ago, and work our way forward to the present day. This is a challenge, but the chapter gives you essential knowledge of the universe and our place in it so you can appreciate what you are going to see on your cruise. This alone will not make you an expert, but you will at least have some useful astronomical background when looking at and photographing the sky, which I truly believe enhances both activities.

To be candid, you do not have to have any astronomical knowledge to enjoy looking at and photographing the sky. So you can skip this chapter if you like. The chapters that follow provide astronomical information on specific astronomical objects and provide astrophotography tips at the end of each chapter for photographing them. You can bypass the astronomical information in these chapters, but you will want to come back to them and refer to the astrophotography tips they contain when you get ready to start taking pictures. Having the astrophotography tips in Part I and under each specific astronomical object makes it easier to refer to when you start to take astrophotos.

It is hoped that you will get the astronomy bug and will make it a lifelong passion that will serve you well as it has so many others, myself included. From collective experiences onboard ship, public speaking, and the astronomy education of adult learners, I can tell you this – once you realize that you can understand the universe, the more you will want to do so. This book may be the impetus to start you on your way.

When you are finally on the ship, settled in and exploring your new “observatory,” you will need the practical tips in Chap. 3 , “Using Your Ship Observatory at Sea,” on how to make the most of your astronomy-astrophotography efforts onboard. Every single ship is different, even those of the same class, like the popular R-ships used by Oceania and Azamara and the “Dam Ships” of the various classes of Holland America Lines. The captain may have “Full-Dress Ship ” in force, which means you are going to have a lot of light out on deck at night.

You really need to learn the ship’s deck plan : port (left), starboard (right), forward and bow , aft, and stern . You will want to know if you can access the bow, whether the main deck goes completely around the ship and what is the highest accessible deck. Knowing the ship’s position , her course, and weather is absolutely crucial to planning an astrophotography session. This chapter also begins to blend available (hopefully!) information technology (IT) at sea with your planning and execution efforts. You will get high-tech pointers backed up with old-fashioned methods just in case the access to IT is not available, which can happen at sea or you do not wish to go that high-tech route.

Where you are in the world literally determines what you can see in the sky. In real estate, it is “Location, Location, Location.” Well, so it is in Chap. 4 , “Location, Location, Location.” Are you in the Northern or Southern Hemisphere? Crossing the equator north to south or south to north, or cruising along it? What time of year is it? What time zone is the ship in? All of this has to be taken into consideration when you are cruising. And if you are on one of the “Grand Voyages ” or “World Voyages” that can cross vast distances and involve weeks or even months at sea, you will experience significant changes in your astronomy -astrophotography experiences. The chapter will build upon what you learned in Chap. 3 and help you in observing or photographing the sky from around the planet.

Chapter 5 , “The Sun , Sunsets , Sunrises and More,” starts off the chapter sequence providing the basic details and knowledge of specific astronomical objects and events you can see with the unaided eye or using optical aid . You do not need telescopes at sea unless you really want to have them, but monoculars and binoculars are encouraged. Each of these chapters will also have information on photographing to serve as a reference for taking astrophotographs of the astronomical object(s) described in the chapter. Hopefully this will be more convenient for you than having to go back into Part II to get this information.

Naturally we begin with our star, the Sun. At the very start of this chapter, you are provided with solar safety precautions that MUST be followed in order to protect not only your camera but your eyes. Failure to do so will damage your camera and your vision.

Safely done the Sun provides a very interesting and beautiful object to observe and photograph, especially during what one captain calls “the magic hours of sunrise and sunset .” Indeed, these times of day provide potentially breathtaking vistas of sea and sky that are not to be missed.

The chapter also includes a bit of astronomical background on the Sun for your reading pleasure and a bit of meteorological information as it pertains to clouds. Who would have thought that clouds would enter into an astronomical discussion, but they do here with good reason. The ship will provide you with all of the weather information you will need on your cruise, but clouds will become a vital contributor (or inhibitor) to your photographic composition when it comes to those magic hours of sunrise and sunset . Rays, shadows, rainbows , sun dogs , solar halos , the (in)famous green flash , and the interplay of light and waves  – all await your camera and eyes.

A highlight of this chapter is the description of a phenomenon you have probably seen many times before but maybe did not realize what you were looking at – Earth’s shadow . Occurring before every sunrise and after every sunset, this is an experience not to be missed.

Moving from day into night, Chap. 6 , “The Stars,” takes center stage. At sea, thousands of miles from land during trans- Atlantic or trans-Pacific voyages, the night sky literally is covered with stars due to the absence of ashore light pollution . Even in proximity to land, unless you are near a major metropolitan city or high population density area such as the Mediterranean Sea, you will be away from significant light pollution. The stars have different colors and levels of brightness, form actual shapes in the sky that you can see – the 88 constellations  – and show us what seasons are occurring. All of the individual stars you will see belong to our Milky Way Galaxy . You will learn about the lives of the stars and how they are so essential to the universe and us.

Speaking of our home galaxy, the Milky Way , it and some of the galaxies you can see with your unaided eye are the subject of Chap. 7 , “The Milky Way and Other Galaxies.” You will want to make this a “must-see” on each of your cruises, as there are few sights that a human can experience that are more awe-inspiring than seeing the Milky Way from a dark sky site. Nearly 80% of the human population in North America cannot see this ghostly band of light due to light pollution . I have had people get misty eyed when they saw our home in the realm of the galaxies for the first time. At sea, whether it be in the Northern or Southern Hemisphere, when skies are clear, the Moon is not interfering due to its phase with resulting light output, and the Milky Way is above the horizon, you will be spellbound.

It takes some planning to see the Milky Way at its best, based on the phase of the Moon, the ship’s location, and the time of the year. I will take you through all of this and will also include a special section on the Large and Small Magellanic Clouds  – dwarf galaxies that are moving through space with the Milky Way  – which you can see from lower northern latitudes and prominently in the Southern Hemisphere’s higher latitudes. I will also introduce you to the farthest thing you can see with your unaided eyes, the Andromeda Galaxy .

There are five planets in our Solar System that are easily visible to the unaided eye and are a cinch to see at sea with a clear horizon and sky. In Chap. 8 , “The Planets,” you will find out what you need to know to locate the two planets closest to the Sun, Mercury and Venus. They are visible in the hours before sunrise and after sunset throughout the year at varying times. Mercury presents some interesting problems as to finding and photographing it, while Venus is so bright it can actually be seen during the day when conditions are right. In the darkness of nighttime Mars , Jupiter and Saturn reign when they are visible. The planets are constantly changing their positions in the sky due to their orbiting around the Sun as well as our own planet’s motion around the Sun. You might even be able to spot and photograph outwardly Uranus at several billion miles from Earth. Neptune and Pluto are probably beyond your reach at sea.

Well, as a self-confessed lunatic of the astronomical type, i.e., loving all things lunar, Chap. 9 , “The Moon,” is a labor of love. As the Moon goes through its phases over the course of four plus weeks, it will dominate your sky in so many ways. The phase of the Moon will determine where it is in the sky and how much light it is pouring into the night sky and provide you with wonderful photographic opportunities.

The Moon interacts with clouds, the sea, stars, and planets. It moves in the sky from night to night (even hour to hour), ever changing in its phase, and it always draws us to it with our eyes and camera. Whether with just your own eyes or with telephoto or wide-angle lenses, you will want to see and photograph Luna at some point on your cruise. Descriptions of what you are seeing on the Moon, the latest in how astronomers think the Moon was formed, and how humanity is headed back to the Moon in a big and hopefully lasting way round out this chapter.

Have you ever seen a partial or total eclipse of the Moon or Sun? In Chap. 10 , “Eclipses,” safe solar eclipse viewing tips similar to those discussed in Chap. 5 will be provided and MUST be followed, as this is vital to eye and camera safety.

We will cover the basics behind these astronomical phenomena, and I will share with you at-sea experiences with both. As a two-time “umbraphile” standing in the shadow of the Moon during a total solar eclipse , once at sea and once on land, I have gained perspective. I have lost count of my total lunar eclipses , but it is in the dozens on land with several at sea. Cruise lines are incorporating these eclipse events into specific cruise bookings, which is a good thing for seagoing eclipse chasers.

Ever spotted the International Space Station (ISS) or a satellite crossing the night sky? Chapter 11 , “Spotting the International Space Station and Other Satellites,” provides information on how to determine when these fascinating machines will cross your sky. ISS is really bright and quite the sight to see. You will want to determine if ISS will be visible when you head out to sea, and you will learn how to do so. You will also get tips for spotting satellites such as the Hubble Space Telescope (HST) and others.

Each year as Earth orbits the Sun, our planet passes through major debris streams left behind by comets and asteroids . Chapter 12 , “Asteroids and Comets, Meteor Showers, Fireballs and Bolides,” provides you with information about these heavenly showers and how to see them as well as their Solar System relatives. I was on a cruise that was partially dedicated to December’s Geminid meteor shower , and it was very cool. If you spend a lot of time up on deck at night, you might see “falling stars” or even fireballs, whereas seeing comets and asteroids is dependent on your location, their position, and most importantly their brightness in the sky.

Regarding Chap. 13 , “ Auroras and Other Glows in the Sea and Sky,” safe solar viewing tips similar to those discussed in Chaps. 5 and 10 will be provided and MUST be followed.

I have seen an auroral display at sea off the coast of Alaska and it was simply astounding. There are cruise lines dedicated to seeing them. I have seen one aurora event while docked in northern Europe that clouds mostly hid it, and I have seen several on land. These shimmering curtains of light are for the most part confined to the higher latitudes of the Northern and Southern Hemisphere but can sometimes migrate to lower latitudes . You will be provided some of the websites that on an hourly basis track aurora locations and probabilities of seeing one. There are other glowing phenomena that can appear in the Western sky after sunset, or in the East hours before dawn, called the zodiacal light , zodiacal band, and after midnight in the South, the Gegenschein. These ghostly apparitions are well suited to being seen at sea due to the uncluttered sea horizon and absence of lights. And they are something to see.

Part II, Astrophotography at Sea , gets into the nuts and bolts of taking photographs at sea, primarily of an astronomical nature. You will have seen from some of the chapters in Part I that it is possible to take quality pictures of eclipses, the Moon, stars, planets, and the Milky Way , to name a few. I will share my tips, procedures, and experiences with you so that you, too, can become a seagoing astrophotographer.

Chapter 14 , “Yes, It Can Be Done and How To Do It,” is where I try to convince you that taking pictures of astronomical objects on a vessel underway in the oceans and seas of the world is not only possible but that you can do it. As to gear, we will go from smartphones to digital single-lens reflex (DSLR) cameras and everything in between. This is not a primer on all of the ins and outs of photography but will get you launched on taking astrophotographs at sea whenever you are ready to do so.

Chapter 15 could have been named “The School of Hard Knocks,” but we chose a more positive message: “Redfern’s Rules of Astrophotography at Sea.” These seagoing astrophotography rules are based on hard knocks, mistakes, frustration, and well over a year to date actually spent at sea aboard 28 and counting cruises. I will share my growing pains in this unique niche of photography with you as they are instructive and will help you to avoid the pitfalls. Adhering to them will go a long way in getting astrophotographs that you will be proud of and, I truly think, amazed by.

If you did your homework right in Chap. 3 , “Using Your Ship-Observatory at Sea,” then you will be all set for Chap. 16 , “Preparing for Your At-Sea Astrophotography Session.” This is where you transition from visually observing the sky and just reading about astrophotography to actually start taking exposures. You will learn, and see, how your camera is far more sensitive to the maritime environment than you and your eyes are. Using proven at-sea tips plus what you have learned from the previous chapters will enable you to plan and execute your astrophotography sessions onboard your cruise ship. I will also integrate the discussion on astronomical software from Chap. 1 , “ Cruise Considerations and What to Pack Astronomy -Wise,” into this chapter.

Chapter 17 , “Astrophotos – Taking What the Sea, Sky and Ship Will Give You,” is where philosophy and practicality meet in a big way. Up to this point, I have shared with you, literally, all that I know and have experienced in astronomy and astrophotography at sea. Now I want to help you gain an appreciation and passion for our shared interest. There are not many people who undertake this pursuit of ours in photographing the universe while at sea, although I hope this book changes that. We as astrophotographers at sea have to evaluate and respond to what the sea, sky, and ship give us. Each is an entity unto itself, and we must take what we know about each of them and apply it to each and every session.

Truth be told, this applies to your visual astronomical observing sessions as well, but the addition of a camera makes it more complicated. When you have acquired the “Zen” of astrophotography at sea, you will be well equipped to capture photons that have traveled through space and time to your camera at a precise moment and place. That, dear reader, is when the true recognition of what you have accomplished will come shining through in the astrophotographs you have created.

Another confession here. I do minimal processing of my astronomical images, and in Chap. 18 , “Process, Print and Post,” I will share with you what those processes are. They are basic but adequate to get great astrophotographs as you will have seen from the pictures in this book. One thing I will tell you as an absolute and inviolate rule of mine – I never add color to my astrophotographs. I will adjust other parameters as needed but have never nor ever will add color. Another point to share is that I do not use anything other than freeware or image processing software that came with my camera and computer (Mac). You can use whatever image processing software you want, but true to my word, this book is about basics, and basics gets the job done in this important area.

I am a big fan on sharing my astrophotographs with social media outlets such as Twitter and Facebook, as well as in my presentations. Instagram and Flickr will also be briefly described in case you want to start posting all of your astrophotographs online so others can see them. If I think an astrophotograph is good enough or may generate interest, I may even submit it to organizations for publication consideration. I have been fortunate enough to have a number of my astrophotographs published online and in print. The names of various online and hard-copy outlets will be provided. Speaking of print, I briefly discuss ways you can go about getting your favorite astrophotographs printed.

If I have done my job properly in writing this book, then you will be interested in the contents of Chap. 19 , “Bringing the Astrophotography Bug Ashore.” Why stop taking astrophotographs of the sky when you get back home? It will be far easier to do on land, and you can expand your horizons literally by thinking about using bigger telephoto lenses , motorized mounts that can guide your camera for very long exposures, upgrading to sophisticated astronomical and image processing software , or even getting a telescope. This is where astronomy and astrophotography may become one in the same for you, as you will have to beef up your knowledge of the universe to properly use and appreciate a telescope. Telescopes, when properly chosen, can last a lifetime and provide a lot of enjoyment and satisfaction. I will give you tips on how to select a telescope and get further involved in astronomy, such as joining a local astronomy club or even taking a free online astronomy class.

This chapter will also discuss how you can take what you have learned at sea and apply it to being on a small craft, by a lake or seashore, or a dark sky site ashore. These environments are an extension of what you experienced at sea, and the skills and techniques you have learned are very easily applied to them.

So here we go, shipmate. Underway and shift colors. The sea and stars await us. You never know what the sea and sky will reveal to you.

Fig. 1

Note: All images in this book, unless otherwise annotated, used an “Automatic” setting for “White Balance”.

Object viewed: Iceberg. (Image by the author)

Ship: Azamara Pursuit

Lens used: 28–300 mm at 300 mm f/5.6

ISO : 5000

Exposure: 1/13 second

Comment: Iceberg off the starboard side in the Arctic Ocean. High ISO due to deep dusk and high wind

Gregory I. Redfern

Ruckersville, VA, USA

Acknowledgments

I wish to thank my Springer Editors Hannah Kaufman and Maury Solomon for their tireless and most welcomed efforts plus taking a chance on me and my book, the Springer team that printed my book and Dr. Harold E. Geller, Observatory Director, George Mason University, for his contributions.

Author’s Note

The book is intended for people who will be going on cruises or spending time on other bodies of water and want to learn how to observe and photograph the night sky while doing so. It is not an astronomy, photography, or nautical/navigation textbook, although there will be some information from each of these topic areas included. It is a practical guide to the subject that quite frankly I have not been able to find anywhere else. After all, who really thinks about astronomy and astrophotography on a cruise ship? Well, you and I do, which is why I wrote the book.

When it comes to the natural world, the two greatest passions in my life have been the sea and the sky. The former came alive as a result of my being in the U.S. Navy as a seagoing naval officer and the latter as a young child looking up at the dark skies of Nebraska.

As the navigator on a guided missile destroyer escort in 1974–1975 and on deployment to the Western Pacific, I had to rely on celestial navigation using a sextant to find our position in the deep southern portions of the Indian Ocean and Pacific. No reliable electronic navigational aids for those areas were available. The knowledge of the night sky I had acquired growing up came in very handy, as the stars and constellations were second nature to me.

I also did a Western Pacific deployment from 1981 to 1982 as a civilian aboard an aircraft carrier. Assigned no watch-standing duties, I had the luxury of many a night in a darkened ship condition to see the stars when there were no flight ops scheduled. I would go to the bow and sit down with nothing in front of me but sea and stars.

Running in darkened ship conditions and thousands of miles from the nearest light bulb ashore really showed me the sky as few landlubbers ever see it. The sound of the ship’s hull making a path in the dark waters of the Indian Ocean with no apparent horizon to separate sea from sky makes it easy to lose yourself in the universe.

My most spectacular night ever at sea under the stars was when the carrier was in the Indian Ocean below the equator and we were having a rare stand-down from night flight ops. It was a night when the sea was mirror smooth with no wind and the sky was ablaze in the dark water as well as overhead. From my bow perch, I could see a totally encompassing expanse of stars – it was like I was at the center of the universe. The Solar System was undergoing syzygy, so all of the visible planets were there as well as the down under Milky Way of the Southern Hemisphere.

My seagoing days would end when I rotated off the carrier, until February 1998. That was when I enjoyed my first civilian cruise ship experience – a 10-day total solar eclipse expedition aboard Statendam in which I was part of the Sky & Telescope /Science Expeditions staff. Our Holland America three-ship fleet enjoyed a wonderful view of the Moon’s shadow – the umbra – racing across the Caribbean Sea to engulf us in the dark of day as only a total solar eclipse can do.

During the years of being on land, my astronomical pursuits encompassed becoming an adjunct astronomy professor for five different colleges and universities, appearances on radio and television regarding astronomy events in the sky, and writing astronomy columns and stories for newspapers and magazines. My civilian career with the Department of the Navy took me literally around the world with my family. We lived a total of 5 years on the islands of Adak, Alaska, and Guam before finally settling down in Virginia.

Adak had 3 clear days and nights a year on average, and I probably became the only human in history to photograph Halley’s Comet from there in 1986. I took my University of Alaska astronomy classes out to see the stars, whenever we had the chance. Bounded by the Bering Sea to the north and the northern Pacific Ocean to the south, that was not very often.

The glorious tropical skies of Guam at 13 degrees North latitude, with the Philippine Sea to the North and the Pacific Ocean to the South, afforded ample opportunities – between the seven typhoons and annual rainy seasons we experienced – to see and photograph the sky.

Upon settling in Virginia, I continued teaching part time and observing/photographing the sky. I became affiliated with NASA in 2003 as a volunteer through the Solar System Ambassador Program, which is managed by the Jet Propulsion Laboratory (JPL). My astronomy and space outreach really picked up as well as access to NASA facilities.

Upon getting close to retirement, I began in earnest to apply for cruise lecturer positions as a Special Interest Lecturer – Astronomy and Space. I was fortunate enough to be accepted by several cruise lines and companies, so I retired and started going back to sea in October 2013.

I have probably spent about 1000 nights at sea and 2000 nights ashore observing, photographing, and gazing at the stars. I have a lifetime habit of always going out and looking at the sky to end my day regardless of weather.

In writing Cruise Ship Astronomy and Astrophotography , I wanted to share with you my experience gained from my two passions, so you can undertake observing and photographing the night sky for yourself while at sea. It is a practical guide you can use before heading out to sea as well as once you are at sea. I have included some information on the universe so you can have an appreciation for what you are seeing. I have provided sources of information and suggested reading you can access to go deeper in the science of astronomy if you so desire. If, like me, your desire to observe and photograph the universe does not end when ashore, you will find information and tips on how to do so.

Whether you are a passenger on a cruise ship or in command of your own private vessel, I think you will find value in reading my book if the stars call to you while at sea, on the waters of a lake, or at a dark sky site on land. My hope is that you, too, will come to experience the melding of sea and sky with camera and the eye.

Wishing you fair winds and following seas under a clear and dark sky….

Contents

Part I Cruise Ship Astronomy

1 Cruise Considerations and What to Pack Astronomy-Wise 3

Why Cruise?​ 3

Choosing a Cruise Line 4

Shore Excursions 8

What to Pack 12

Carry-on Baggage Compliant Backpack (S/​A) 13

A Quality Red/​White LED Headband Unit (S/​A) 14

Astronomy Software (S/​A) 15

Computer (S/​A) 17

Smartphones (S/​A) 17

Tablet (S/​A) 18

Printed Observer’s Handbook or Astronomy Magazines (S/A) 18

Telescope, Binoculars or Monoculars (A) 19

All Aboard! 21

2 Big Bang to Homo Erectus to Multi-Messenger Astronomy 23

3 Using Your Ship-Observatory at Sea 45

Getting Familiar with Your Ship 45

Safety Tips 47

The Main Deck 47

Your Stateroom’s TV Information Channel 50

Knowing the Weather 53

Your Ship’s Course 54

4 Location, Location, Location 59

5 The Sun, Sunsets, Sunrises and More 75

Solar Viewing and Solar Photography Safety 75

Our Star, the Sun 77

Photographing Sunrise and Sunset 80

The Green Flash 86

Seeing Earth’s Shadow 88

Other Atmospheric Phenomena 91

6 The Stars 95

Photographing the Stars 106

7 The Milky Way and Other Galaxies 111

Photographing the Milky Way 120

Photographing the Southern Cross 127

Photographing the LMC and SMC 129

Photographing the Andromeda Galaxy 130

8 The Planets 133

Mercury 136

Venus 139

Mars 143

Jupiter 145

Saturn 146

Uranus 147

Neptune 148

Pluto 149

9 The Moon 151

Origin of the Moon 152

Visiting the Moon 153

Viewing the Moon at Sea 157

Photographing the Moon 166

Moon Phases 167

Moon and Planets 168

Lunar Occultation of a Planet or Star 169

Moon, Water, Clouds 169

10 Eclipses 171

Understanding Eclipses 173

Preparing for Solar Eclipses 176

Eclipse Type 179

Ship’s Date 180

Ship’s Time for Eclipse Events 180

Sun’s Altitude/​Azimuth 180

Planned Photographic Settings 180

Photographing a Total Solar Eclipses 180

Partial Solar Eclipses 195

Pinhole Projection 195

Photographing the Partial Eclipse 196

Photographing Annular Solar Eclipses 197

Hybrid Solar Eclipses 198

Lunar Eclipses 198

Photographing Lunar Eclipses 200

Total Lunar Eclipse 200

Partial Lunar Eclipses 202

Penumbral Lunar Eclipse 202

11 Spotting the International Space Station and Other Satellites 203

Spotting Satellites 203

Photographing the ISS and Satellites 206

12 Asteroids and Comets, Meteor Showers, Fireballs and Bolides 209

Understanding Cosmic Debris 209

Photographing Asteroids and Comets 214

Viewing Comets and Meteor Showers 215

Photographing a Meteor Shower and Meteors 217

13 Auroras and Other Glows in the Sea and Sky 221

Auroras 221

Airglow 225

NLCs 229

The Zodiacal Light 230

Solar Phenomena 234

Rainbows and Moonbows 238

Lightning at Sea 240

Bioluminescence 244

Part II Astrophotography at Sea

14 Yes, It Can Be Done and How to Do It 249

15 Redfern’s Rules of Astrophotography​ at Sea 259

Rule #1:​ Read the Camera Manual 260

Rule #2:​ Read the Camera Manual 261

Rule #3:​ Keep a Hand on Your Camera and Gear at All Times 262

Rule #4:​ More Is Better – Shoot, Shoot, Shoot Pictures 265

Rule #5:​ Use the Highest ISO Feasible 266

Rule #6:​ Speed Wins – Use the Fastest Shutter Speed 266

Rule #7:​ Use the Widest Angle Lens You Have 267

Rule #8:​ Have a Red Headlamp for at Night 268

Spare Batteries for Your Camera 269

Lens Cleaning Kit 269

Extra Lens and Camera Body Protection Caps 269

Extra Camera Body LCD Panel Protectors 269

Extra Tripod Plate Adapter for Your Camera Body 270

Rule #9:​ Keep the Color Real 270

Rule #10:​ Take What the Ship, Sea &​ Sky Give You 270

16 Preparing for Your At-Sea Astrophotography​ Session 271

Astrophotography​ Session Checklists 272

17 Taking What the Sea, Sky and Ship Will Give You 281

18 Process, Print and Post 289

19 Bringing the Astrophotography​ Bug Ashore 301

Appendix:​ Suggested Reading and Internet Sites 313

Index 335

About the Author

Greg Redfern

 is known on Twitter as “@SkyGuyinVA” and on Facebook as “Greg Redfern”. He has been an adjunct professor/instructor of astronomy for five different colleges since 1984 and a NASA JPL Solar System Ambassador volunteer since 2003. He has shared NASA’s missions to the Solar System with many audiences in person as well as on Fox 5 WTTG TV, WJLA TV, WUSA TV, WRC TV and WTOP and WBAL Radio in the Washington, D.C., media market. Greg’s daily astronomy blog, “What’s Up The Space Place.com,” has had over three million views from around the world.

As a writer, Greg has authored numerous articles for Sky & Telescope magazine, Meteorite magazine, and Skywatch magazine and a number of newspapers including Gannet and USA Today .

Greg has been observing and photographing the sky for over five decades and collecting meteorites for years. He has used telescopes of all kinds and visited observatories, NASA facilities, and geological sites.

His astrophotographs have appeared in many publications and on various Internet sites, including:

NASA.gov

MSN.com

huffingtonpost.com

Washingtonpost.com

The Planetary Society.org

Sky and Telescope.com

Space.com

Earth and Sky.org

Earth Picture of the Day.org

Universe Today.com

Shenandoah National Park websites

WTTG TV

WUSA TV

NBC4 TV

WTOP.com

Virginia Tourism.org

Azamara Cruises Twitter

Windstar Cruises Twitter

Holland America Line Twitter

Cruise ship guests and audiences ashore around the world have truly enjoyed Greg’s presentations as well as viewing the night sky with him, where he mingles the folklore and science of the stars.

Part ICruise Ship Astronomy

© Springer Nature Switzerland AG 2018

Gregory I. RedfernCruise Ship Astronomy and AstrophotographyThe Patrick Moore Practical Astronomy Serieshttps://doi.org/10.1007/978-3-030-00958-8_1

1. Cruise Considerations and What to Pack Astronomy-Wise

Gregory I. Redfern1  

(1)

NASA JPL Solar System Ambassador , Ruckersville, VA, USA

Gregory I. Redfern

Why Cruise?

Cruising , as most call it, is a travel industry segment that is growing by leaps and bounds, as exhibited by the large number of cruise ships on order by the cruise lines. New ships are being built in order to meet cruise ship passenger growth that is projected to keep increasing in the coming years.

What is it about cruising that is causing all of this to happen?

Cruising is unique in that it combines time at sea with ports of call. Of course you can fly, go by car or bus, take a train or do a combination of some or all of these transportation modes to multiple or singular destinations. For each place to be visited you have to reserve lodging, obtain meals, possibly secure professional tour guides and hire reliable transportation to see all of the sights your destination(s) have to offer. You can work with a travel agent and tour companies or do it yourself to put all of the pieces of your vacation puzzle together. That is a lot of work! Some people thrive on the logistics of vacation planning and the ultimate freedom of choice it offers. Others, most probably the majority of travelers today, do not want that kind of hassle. One-stop shopping for your travel needs and desires is where cruising shines.

Many guests have commented that the main reasons they cruise are comfort and convenience. Some have said, “I don’t like to fly,” and added that the cost of first class or business airfare to go across the Atlantic, for instance, is comparable to booking on a cruise line that will take them across the Atlantic. They have the time to spare in taking the slower mode of transportation, so they would much rather spend time on a cruise ship than fly. To them it is much more relaxing and enjoyable. There was also the consideration of the guest’s health and mobility in their travel choices. Guests who need assistance with mobility or have health issues commented that it was much easier to cruise than to fly. Wheelchairs, electric scooters, walkers and portable oxygen supplies can be regularly seen on cruise ships.

The convenience and comfort aspects also come to the fore when you realize that in booking a cruise you can have all of your vacation logistics taken care of. All cruise ships depart from a port, usually from a designated “cruise terminal” that is part of the port, to begin and end their voyage. Some of these ports in the United States have parking available, like an airport, as you can drive there and leave your car parked or take a cab or other public transportation to the cruise terminal. Some of the cruises out of these ports are round trip; that is, they depart and return to the terminal. Others depart and cruise to other destinations.

If you have to fly to reach your ship’s departure port the cruise lines or your travel agent should be able to help you with these airline arrangements, including shore transportation from the airport to the ship and from the ship to the airport.

Choosing a Cruise Line

The number of cruise lines to choose from is extensive and somewhat comparable to your choices of major airlines, rail lines, and bus companies. The author’s personal experience so far extends only to Azamara Club Voyages, Cunard, Holland America Lines, Oceania Cruises, Regent Seven Seas Cruises, Royal Caribbean International, Sea Dream Yacht Club and Windstar Cruises Line. What is shared in this book comes from the experiences with these cruise lines and is probably typical of what occurs on most cruise lines.

If you do a Google search on “Cruise Line Listing” you get 3,680,000 results! You will see links to the listings of the current and defunct cruise lines (many of them morphed into other cruise lines), which seems pretty accurate although we obviously did not check them all due to the sheer number of them.

If you view the listings in the Appendix of this book you will notice that there are “River Cruise Lines” also. Having never been on one of these types of cruises limits commentary to only what has been shared by some of those who have sailed on this type of cruise. These vessels sail on some of the major rivers around the world and are comfortable and enjoyable. If you go on one of these cruises what you will learn in this book should be applicable for the most part. After all, it is a vessel underway on water, just much, much smaller than the oceangoing cruise ships. Also, the distance you traveled, number of decks and the farthest height above the water will be different from oceangoing cruise ships.

To settle on a specific cruise line is like trying to decide which car to purchase as a first time buyer. They all perform the same basic functions they were designed to do. It becomes a matter of personal preferences as to style, cost, available options and for a car, how it feels during the test drive. Well, the same selection process applies to picking a cruise line. But to take a “test drive” of a specific cruise line is a little more complicated and involves some cost.

You can try to find a cruise that is only a few days in length so you can test your “sea legs” and find out if cruising is for you. But even before taking the test cruise you are still left with the question, “Which cruise line is for me?” Let’s take a look at how you might want to go about selecting a cruise line. We’ll discuss first the common considerations and then add in those with an astronomical flavor.

Truth be told, you may want to just find a travel agent who can help you. Nowadays you can even book cruises by going through your airline’s points program, nationwide membership and financial organizations and even the large wholesale membership retail warehouses. They all advertise cruises and cost savings for members.

Even if you book your cruise using any of the foregoing methods it pays to do some research on your own. You don’t have to, as each of the just mentioned entities will assist you, but it will help you out in the long run. Besides, at some point you are going to have to get into the details of your cruise online and/or in hard copy. There is no way around it unless you have a full time consigliore or personal assistant to help you. Don’t laugh; you could see this on a cruise!

If you are on your own, your first step in looking for a cruise line could be as simple as asking friends and relatives that you know have taken cruises what their experiences were like. Ask them about the cost, accommodations, food, entertainment, the overall atmosphere and ambiance on board, how they were treated by the crew, and don’t forget to inquire about the quality of the offered shore excursions. People form pretty strong opinions about cruise lines, just like they do about cars in terms of whether they are great or lemons.

If you are able to gain such information this might steer you to check out some of the popular cruise lines further. If you weren’t able to have such input it’s OK, as everyone should take this next step anyway – go online. Surfing the Internet to check out the cruise lines is highly recommended for several reasons. Just as there are critics and reviews of car manufacturers and their individual models, so there are reviews of cruise lines and even individual ships. You can read online various cruise critical reviews as well as travel oriented and mainstream media (including the travel sections of major newspapers) stories about cruising, specific voyages and ships, “Top 10” lists, etc. Such information is available as printed media as well.

Here are a couple of other things to consider at the start of your selection search. First and foremost is, “What size ship do I want to be on?” Do you want to be on a big ship, which is generally considered to be somewhere in the neighborhood of 80,000 to 100,000 tons or more? There are cruise ships now afloat that are in the 200,000-plus tons class! That is twice the tonnage of a Nimitz-class nuclear-powered aircraft carrier and comparable in length. These mega-ships also have many decks and are quite a distance above the water on their topmost deck. When you go big you will share your cruise with from 2,000 to 6,000-plus passengers. These big ships also offer a lot of amenities that smaller ships cannot, such as ice skating rinks, rock climbing walls, large sport complexes that may include wave surfing, water slides, simulated skydiving, and zip line rides, to name a few. Some of these ships also offer a ride that carries you out over the water and above the ship as well as extensive outdoor entertainment facilities. These ships can also have different themed decks that mimic life from different countries and in some cases cities. They really are amazing vessels.

There are ships that are moderate sized, in the 30,000- to 60,000-ton range that might have approximately 700 to 1,500 passengers. They might not have all of the bells and whistles of the bigger ships, but they can go to ports and places their bigger sisters cannot. They do not cut corners just because they are smaller, though, and have a big following of loyal cruisers who think smaller is better. In this class of ship you have a better chance of getting to know other passengers and members of the crew. Activities such as bridge, bingo, cooking classes, etc., have smaller groups as well.

Speaking of smaller, there are several cruise lines that have ships (they really call them luxury yachts) in the 4,000- to 10,000-ton class and carry approximately 100 to 300 passengers. These luxury yachts really are the ultimate in getting to know your fellow guests, the crew and the sea on a very up close and personal level. They really can go places where no other ships can, such as coves and bays in islands or secluded anchorages where the rich and famous hang out. Some of these vessels have a deployable sea well on the stern that can be opened to allow access to swimming/snorkeling in the ocean, jet skis, and sunbathing on your own personal inflatable if weather and safety considerations allow it. Life onboard these vessels is sumptuous, and the sea feels enchantingly close when you are up on deck.

OK. So you have thought about what size of ship and resulting shipboard environment you might like. Now you can get into the nitty-gritty of your online search. You can simply search by inputting small, medium, or large “cruise ship” into your favorite search engine, and the search results will come back listing cruise lines that have that type of ship. You will also get more reviews and articles about these selected cruise lines. It is pretty amazing as to what you can get online. Another way to focus your search for that cruise line made just for you is to search by destination. You can input a country, region of the world or even specific cities and add “by cruise ship” to get results by cruise line.

One other suggestion to help in your search for a cruise is to input “astronomy themed cruises,” which resulted in 766,000 listings! Make this part of your search, as the postings are updated by the cruise lines as they add new cruises. A new comet, upcoming solar and lunar eclipses, and the aurora are favorites for astronomy-themed cruises.

At some point you will hopefully have narrowed down your search to where you have an idea or two as to which cruise line(s) you are interested in. This is where you focus your search as to destinations, length of voyage, cost and overall details of a particular cruise by going to the website of the cruise line(s) you are interested in. Each cruise line’s website will introduce you to their brand and provide details on the company, their ships and their destinations. They really want to sell you on booking with them and provide online chat and telephone numbers for you to connect with a representative.

Most of the cruise line websites are beautifully designed, as it is their bread and butter in reaching out to the traveling public in order to compete for passengers. Each of them allows you to search for cruises by either destination, length of voyage, cost, individual ship or whatever combination of these search items you wish to use. Your search will produce voyages that you can click on to get more details.

The basic format for describing an individual cruise is usually called an itinerary, and it gives you the port from which the cruise departs and the ship’s anticipated schedule at sea and ports of call over the days and nights of the voyage. There usually is an accompanying map that shows the ship’s intended course over the entire cruise. “Anticipated” and “intended” apply to the ship’s itinerary because world events, weather, shipboard medical emergencies and other situations can arise that demand a change in the schedule. Ship’s captains are responsible for everything that happens on their ships, and they always must make their decisions based on the safety of the ship and all aboard her.

How many days and of course nights at sea will the voyage encompass? This is the first of your astronomically related questions that you want to consider in choosing a cruise. Some voyages are ports of call intensive, with few days at sea, while others are “repositioning voyages” that cross the Atlantic or the Pacific. If you want to get that maximum number of days and nights at sea these types of voyages are what you are looking for. Most cruise line websites will have repositioning cruises listed as well as the longer “world or grand voyages .”

Shore Excursions

Here is another astronomically significant factor for you to consider. What shore excursions are included in the voyage? The itinerary will have a section on shore excursions offered as part of the cruise which you can click on and get a description as to what it entails. These excursions usually will cost you extra.

Are there any astronomy-themed shore excursions that are part of your cruise? If there are any world renowned astronomical- or space-themed attractions they may be listed as shore excursions provided by the ship. They may be well worth the price, as to get there on your own would be a huge hassle (Figs. 1.1 and 1.2).

Fig. 1.1

Mayan astronomical ruins at Iximche. (Image by the author)

Fig. 1.2

Observatories atop Mauna Kea in Hawaii. (Image by the author)

Ship Tip

Almost all cruise ships have a stated policy that if one of their shore excursions should be late in returning to the ship on a day when the ship is leaving port, the ship will wait. This is NOT a guaranteed policy if you make shore excursion arrangements on your own. You need to inquire with the Shore Excursions office to see what the ship’s policy is regarding personal shore excursions.

Using the itinerary you can also conduct online research that might reveal observatories, historical landmarks, planetariums, museums, archaeological or geological features with an astronomical or space theme located at each port of call, ones that are not part of a listed shore excursion and which you might want to pursue on your own (Figs. 1.3, 1.4, and 1.5).

Fig. 1.3

One of Tycho Brahe’s observatories in Copenhagen, Denmark. You might consider visiting this on your cruise to Scandinavia. (Image by the author)

Fig. 1.4

Astronomical clock in Messina, Italy, also possible to visit on a cruise to Italy. (Image by the author)

Fig. 1.5

Beautiful statue of Orion and his faithful big dog Sirius in Messina, Italy, also possible to see as an excursion on an Italian cruise. (Image by the author)

Some of these places you might know about already, but for each voyage you should do online research by searching using the area/city name and adding “astronomical interests.” You should get a listing that you can pursue and decide what to see at that port of call. You want to find out how far this attraction is from the ship, as you need to determine if you can you walk there or whether you need a taxi or a guide. Be mindful of the earlier shore tip in your planning and allow plenty of time to get back to the ship if it is a port departure day.

While ashore and before you embark on the ship the cruise line representative or your travel agent might be able to help you make travel arrangements if needed. When on board the ship Guest Relations, Shore Excursions or the consigliore might be able to help you also.

Once you are aboard and underway on your cruise the ship will provide shore excursion and port information and possibly destination lectures as well that will provide many details on the ports you will be visiting. This is an excellent information resource, and it is highly recommended that you attend each of these events. When the ship pulls into port there may even be local representatives to help answer questions and provide maps and guidebooks.

One other check you want to make when shopping for a cruise is whether there are any significant astronomical events taking place during the voyage. This is a lesson you don’t want to learn the hard way. During this author’s second cruise as a lecturer, he was surprised to find that he would be smack in the middle of an almost total solar eclipse! With no direct solar viewing capability, he still was able to improvise, as you will learn about in Chap. 10, “Eclipses.”

The easiest way to do this check is to refer to the astronomical publications and software described later in this chapter. The most significant events will involve eclipses, major meteor showers and perhaps a newly discovered and visible comet. You can also use these tools to find out what planets and constellations will be visible on prospective cruises to help you in your choices.

What to Pack

After you do your research, considerations and final analysis, what will it be? Cruise or no cruise? If you decide to go and book your passage, the next thing becomes what to pack. Every cruiser must be always mindful of what goes into the luggage due to airline baggage/weight limitations (always verify these with your airlines!) as well as the limited closet/storage space aboard ship – especially if there are two of you sharing a stateroom. The cruise lines’ web pages offer tips on what to bring for your cruise and provide their “Onboard Attire Policy,” which can be a combination of tuxedo/business suit/evening gown for a few formal nights to shorts and tees during the day with business casual after 6 p.m. It is important to adhere to the ship’s stated attire policy, as if you do not you may be turned away from certain venues on board the ship.

Of course, it’s up to you to decide what to pack for your “normal” travel items, but there are some astronomy/astrophotography essentials to take with you. The good news is that they do not take up much space and are not very expensive to purchase. A suggested list of what to pack is provided below, and each item is highlighted as to its intended use – astronomy or astrophotography. It is recommended that the list be followed for your first cruise to make sure you have the necessary basics. As you spend more at sea time and gain experience you can modify what you pack according to your requirements.

OK, now that you have decided on what cruise you are going to take, what do you want to bring along? I say want as opposed to need, as technically, all you really require to stargaze at sea is one, if not preferably two, functioning eyeballs along with any corrective vision devices such as contacts or eyeglasses.

Ship Tip

Always carry an extra set of eyeglasses as part of your carry-on bag along with your camera, computer and medicines. You never know when the primary pair may go to Davy Jones’ Locker or be damaged beyond use. Make sure the prescription for the backup pair is current also. Nothing is worse – other than no pair at all – than a pair of glasses/contacts that are several prescriptions removed from your current one. Carry them in a hard shell case.

In order of priority as determined by usefulness and ease of packing, here is what you should plan to carry with you when going to sea for stargazing and astrophotography. The two activities are mutual in their equipment requirements in many instances, but there are some exceptions. We have broken them down here by category: ‘S/A’ for stargazing & astrophotography, ‘S’ for stargazing only and ‘A’ for astrophotography only. What camera gear to pack, which is dependent on the type of camera you intend to use, is covered in Chap. 14.

Carry-on Baggage Compliant Backpack (S/A)

Medications, spare eyeglasses, computer and accessories, tripod, camera, lenses, astronomy gear and travel documents should be packed in a carry-on compliant computer/camera backpack designed to protect these items. This can be carried also on an aircraft, as it will fit in the overhead bin or under the seat. NOTE: You really do not want to check these items as baggage on any mode of transportation, as they could get lost, stolen and damaged, so this item is essential.

For this requirement you might want to consider the Airport Essentials Backpack available from a company called Think Tank Photo. It is their smallest model, but it will carry everything and still fit under the airline seat. Nowadays there is no guarantee of an overhead bin for storage space, so you have to assume you will have to stow your backpack under the airline seat in front of you. On the ship you can grab it and go topside for your astrophotography sessions. It is very convenient, as you might need to negotiate ladders and heavy doors with both hands free. The backpack also protects gear while traveling and when it is set down on deck. This backpack can also carry a tablet, has a rain flap, chest and waist straps (helps distribute the load) and a horizontal and vertical carrying handle (durable nylon). On one side it can also store a tripod using a mesh pocket to hold some of the leg/footpad and two straps to secure the folded up tripod. SAFETY NOTE: You want to secure your tripod so that it has no dangerous protrusions – especially the large bolt where the tripod head is attached – that could injure you or a bystander. Consult your tripod User’s Manual to learn how to properly and safely fold up your tripod. Also read the backpack’s User Manual for safety and protecting your expensive gear. Be sure to tuck in all of the backpack’s straps to get them out of the way so they don’t catch on anything before you go on a plane – I do this while waiting to board. Do yourself a favor and buy a backpack that has all of these features. You will thank yourself every time you go on a cruise that you did.

A Quality Red/White LED Headband Unit (S/A)

This is so useful ashore and at sea . You can use it as a regular hand-held LED unit as well as place it on your forehead when you need both hands free. You can use it in red mode to illuminate any hotel/stateroom without having to turn on the lights and disturb anyone else in the room. The red light preserves night vision and illuminates everything quite well.

For use in astrophotography it qualifies as Rule #8 of Redfern’s Rules of Astrophotography; see Chap. 15 for more on this.

It can also be used in an emergency such as a power outage or – heaven forbid – a smoke involved situation with the bright white LED to illuminate your way to safety in an aircraft, hotel, and onboard ship. That extra illumination can really help. That is why we say quality LED. Don’t choose poorly when buying this unit .

Astronomy Software (S/A)

If you don’t want to take hard copy manuals of your devices and camera, download them to a USB stick. Keep this stick with you as part of your carry-on bag or fanny pack. Seal it in a plastic sandwich bag for protection and keep it in your hotel/stateroom safe. You can also load backup copies of any software you use in case you have to reload them.

Ship Tip

Make sure you pack a backup copy of your astronomy software and each device’s instruction manual.

Having this software information is essential, as you may need to look up a function of your software/device(s) or try to determine if it can do something you want it to do but have never tried before – perhaps even troubleshoot it. You may not be able to access the Internet to find a copy of the manual or the manufacturer’s website or your software/device(s) “Help” section, so you will be glad you have the manual to refer to.

If you want to go “low tech” in lieu of software you can use a “planisphere” (a plastic device that shows the entire sky that can be set to local position by lat/long to show the sky at a particular time). The biggest disadvantage to using these on a ship is that you will probably be cruising thousands of miles and large sections of latitude and longitude. A planisphere requires manual manipulation to input these values, and quite frankly it may not cover the range of latitude and longitude you will experience on your cruise.

Planispheres are still in use, but astronomical software for looking at the sky is really the way to go.

Another “low tech” option is to use star charts that depict the entire sky on separate star charts. You have to really know how to use these charts, and their biggest disadvantage is their bulk. This is not what you want to be taking with you when space is at a premium and you are up on a windy deck trying to figure out what you are seeing.

Unless you are confident of knowing the entire sky and all of its 88 constellations regardless of your latitude, longitude, body of water, time of year, time of day, phase of the Moon and position of the planets – NOT(!!!!) – you will need to have a means of knowing what will be visible in the sky from your latitude, longitude and time zone.

The most efficient, precise and recommended method to do so is to use computer software/freeware that is commercially available for Macs and PCs for use on a computer, tablet or smart phone. Just go to your browser and type/click “astronomy software,” and you are on your way to finding what will work for you and your device. Some programs will allow you a trial period, which is useful for that all-important test drive under the night time sky.

It is extremely likely that you will have at least one of these devices that you use ashore and will want to take with you on the ship. It is impossible to know what brand, operating system and overall capability your device has, but there are some general considerations that apply to all.

Astronomy software is very powerful in all it can do. You can see the sky as it appears for dates in the past, present and future. The positions of the Sun, Moon, planets, comets, asteroids and satellites are shown along with accompanying data about them. Stars and constellations, their names and sky positions, are shown, as are the deep sky objects that are visible. You can see what eclipses and celestial events such as Moon, star and planetary alignments will look like. But its biggest advantage is that it can effortlessly update the sky according to your ship’s location and time zone. As they say, “Don’t leave home without it.” You will be severely disadvantaged when it comes to enjoying and photographing the sky if you do.

SkySafari Pro is an excellent choice for iPhone, iPad and Mac users. (No commercial endorsement intended here, though, as there are other equally good products out there for Mac and PC devices.) This software can be used at sea for all astronomical needs and when ashore to control a telescope remotely. It is powerful and easy to use on all of Mac hardware platforms, which is a plus. One program seamlessly fits all that you want.

With this and other software there is a “Use My Current Position” option that inputs your location for you using various IT assets, but this does not always work at sea. You may not have Wi-Fi, cell phone or Global Positional Satellite (GPS) service capability for a number of reasons – the satellite and/or link is down, there is no reception, you do not want to spend the extra money for Wi-Fi or cell service at sea – which means you will have to input your location yourself.

You can provide input as to your location either by geographical name from an extensive pick list provided or input latitude and longitude yourself – see Chap. 4, “Location, Location, Location,” for details. The time zone is automatically provided, which can be confusing because the ship may not keep shipboard time to the software designated time. You will have to adjust accordingly. You can also select time down to the year, month, day, hour, minute, and second. When you set the location and time this changes the view of the sky accordingly; you can run the software to see an entire day/night’s viewing with stars, planets and deep sky objects selected. Simply put, this is the way to go.

Use your smartphone or tablet for your stargazing sessions, as most software will have a “Gyroscope or Compass Mode” that follows your motions with your device while you are looking at the sky, which helps you identify and learn about what you are seeing. It is also a lot easier to transport these devices topside than taking your computer.

If you are going to do astrophotography you will in all probability be using your computer. So have your astronomical software on your machine to help plot out your observing sessions in advance. The bigger screen is also easier on the eyes.

You can set up an “observing list” for a stargazing or astrophotography session that will remind you and provide details on what you want to see and photograph. Oh, and make sure you use the “night vision” option when conducting your stargazing/astrophotography, as it preserves your night vision by using red light to illuminate your screen.

Computer (S/A)

Adding a computer to this list means taking up space and adding weight. You might want to invest in a compact model. You can use the computer for keeping up on email and of course viewing the night sky and processing astrophotographs.

A computer is really a very necessary evil, along with meds, glasses, camera and lenses. You can get by without one, no doubt, but why would you want to, especially if astrophotographs are in your seagoing future? Mac or PC, it’s your choice; smallest/lightest is best. Carry a spare power supply and have storage chip memory (if available as an option) that can be upgraded so you don’t have to worry about the hard drive crashing or storage capacity being maxed out.

Most ships have computers that guests can use if they set up an onboard Internet account. The machines also allow for printing out items such as airline boarding passes. The computers are configured so that downloads of programs are not allowed.

Smartphones (S/A)

Almost everyone has a smartphone, and there is no reason to leave yours behind when you go to sea. The cruise lines have at-sea IT capability and cellular service, each at a cost and occasional issues of non-reception. Using the tips provided previously on astronomy software you can use your phone in place of a computer for stargazing and astrophotography by having your astronomical software loaded and using its camera functions if available (more on this in Part II).

Ship Tip

Contact your cellular service provider before the cruise to get their advice on how to access their service based on your cruise itinerary. Be sure you understand how to set your roaming, data and international settings, as a mistake could be very expensive.

You can carry your smartphone ashore, as nearly everywhere has cellular service, but you really have to be careful as to roaming charges, data charges, etc. Carry your phone in a fanny pack so it is not an easy target for a thief and is protected.

Each stateroom has a telephone, and you can make direct calls off of the ship at a set rate. It may be worth comparing the cost of calling home between the ship’s rate and your own at-sea cell phone service.

Tablet (S/A)

These devices are often used by guests for taking pictures (see Part II) and computer functions. They can store e-books and access the Internet. Some these devices can serve as a compromise between smartphone and computer, as they offer a bigger and brighter screen than a smartphone and are far more carry-friendly than a computer. With your astronomy software loaded they are quite convenient to use at night for stargazing sessions.

Printed Observer’s Handbook or Astronomy Magazines (S/A)

Although you can use your astronomical software to plan your observing and astrophotography sessions for any night, it is a bit cumbersome to use it for advanced planning. Sure, you can input a specific date to know what is in the sky that night, but it is far easier to see what the sky is doing days, weeks, months, a whole year in print.

Check out the Royal Canadian Astronomical Society’s Observer’s Handbook for what is happening in the sky for the year. It is chockfull of astronomical and observational information on the Sun, Moon, eclipses, planets, comets, meteor showers, aurora, constellations, stars and deep sky objects. But the most important feature here is the monthly sky guide that details what is happening in the sky each month of the year. If you are going on a cruise or considering one during a specific time period covered by the handbook’s year, you can look up the details. Each year the handbook is available several months prior to the publication year; order it as soon as possible .

Subscribing to either Sky & Telescope or Astronomy magazine is a huge plus in many ways. Each month’s printed and digital editions provide the latest research, space missions, astronomical news, product reviews, astrophotography submissions and details on the sky for the month. As an added bonus it can be something to read on the trip to the ship. We’ll have more to say about this in Chap. 19, “ Bringing the Astrophotography Bug Ashore .”

Ship Tip

Having some form of optical aid is not necessary to enjoy your view of the sky at sea. However, the right optical aid at sea will make your observing time much more enjoyable and memorable.

Telescope, Binoculars or Monoculars (A)

It is not recommended here to bring a telescope with you to sea, although some cruise lines have used them onboard, especially Cunard. Their Queen Mary 2 was the only seagoing planetarium for years, but now Viking Cruises’ Orion has not only a seagoing planetarium but the first ever astronomer in residence onboard! A telescope is an added bonus for embarked cruise guests, but the ship has the huge advantage of not having to pack and ship the telescope – a significant hassle as well as additional expense for you. Their telescopes are not a personally owned item. If it gets damaged it’s on the cruise line, not so if it’s yours!

Let’s check out the ways your telescope can get damaged going to sea.

1.

Transporting it to and from the ship, starting when you leave home and return. Unless you can figure out a way to carry it with you onboard the aircraft, train or bus, i.e., overhead storage or under your seat traveling to and from the ship with you, it is going to get manhandled multiple times. Oh, and this includes getting your telescope on and off the ship, up and down gangways.

2.

It will be a challenge moving it around aboard ship. Even if you use the ship’s elevators to get to your observing deck you will still have to navigate doors and narrow passageways. NOTE: Most ships do not have elevator service to the very top deck; you have to use a narrow ladderway to access it. Good luck with that if you are carrying a telescope and all of its accessories plus camera gear.

3.

Exposure to the elements. It is very likely that your telescope will be susceptible to accumulating sea spray and stack exhaust particles out on the open deck, which will be difficult to clean. Think dried salt crystals and burned carbon bits.

With the foregoing in mind remember and consider this – the calmest seas you can ever experience will never be as if you are on solid ground. There is always motion in the ocean. You can have the best telescope and mount ever made, but the view will always be moving in the eyepiece.

OK, if you still want to bring a telescope on your cruise, the smaller and lighter ones with the widest field of view are what you should consider. Zeroing in on the Moon, planets or the brighter deep sky objects with even modest magnification will be a challenge to see.

A much better optical aid alternative to taking a telescope is to pack binoculars or a monocular. Monoculars are “half” of a binocular; that is, you only have one eyepiece and objective lens instead of two. Some cruise lines offer binoculars as part of the items available in your stateroom, so you should check this out. Also, some cruise lines sell binoculars in their onboard camera/retail stores.

Almost everyone has used these instruments at a sporting event, bird watching or looking at something in the distance. They are self-contained in that they need no other accessories and are easy to use – point and look. But there are considerations to choosing the best for at-sea use.

Binoculars and monoculars have a set of numbers to describe them, for example, “7x50”. The first number, “7,” refers to the magnification (power) and the second number, “50,” tells you how large the objective lens is in millimeters. Each instrument’s description will also provide you a field of view (FOV) in terms of degrees. The best for at-sea astronomical observing needs to combine adequate light-gathering capability with a useful magnification. You also have to consider weight and bulk because of your baggage and storage limitations.

Large astronomical binoculars – 20x80s and others in this class – are not recommended, as they are heavy and will also be susceptible to motion in the ocean. Conversely, going too small in the objective lens size will not collect much light, but anything that will collect more than your own eyes can should offer a better view. The 7x50s have been the watch officer standard aboard ships for a long time and are very popular among amateur astronomers. They are a good choice, as is a monocular in this size.

Here is something for you to consider in your choice of optical aid. It is a bit more expensive but will give you amazing capability. When going to sea the one advantage you want to make the maximum use of is the lack of light pollution. When the bright Moon is out of the sky you want to see the night sky with its stars, planets, the Milky Way, and the aurora in all of their splendor. This does not equate to a high magnification view but rather one that has some magnification, collects a lot of light, and with as wide a field of view as is possible.

To accomplish this Vixen SG 2.1 × 42 binoculars fit the bill to a tee. They are compact and easy to pack in your carry-on. Using them at sea (and land) gives you a view that has been described as having “super vision.” Using them to observe the night sky provides a whole new dimension over the unaided eye alone, almost 3-D.

The bottom line in your choice of optical aid is that anything will be better than your unaided eyes alone.

All Aboard!

The day finally arrives for you to leave for the ship. All of your boarding documents, medicines, astronomy/astrophotography gear and essential items are packed in your carry-on backpack, and your other luggage is ready to go. Your passport, wallet and other essential small items are in your purse/fanny pack. You get to your mode of transportation to the ship in plenty of time for check in and, at the appointed time, board.

Depending on how long your travel time is to the ship really dictates how you spend your time in transit – watching the onboard entertainment, reading – this book, for example, sleeping, conversing. Each mile and minute brings you closer to your ultimate destination – the ship. Here is a typical scenario for what will happen once you arrive at the cruise terminal.

Once at the cruise terminal you walk with your bags or get a porter to take them to check in and you are on your way to boarding the ship, better known as embarkation. You, your luggage and your carry-on will go through security and screening just like at an airport An onboard account will be created in which your shipboard expenses will usually be charged to a credit card you designate, which is kept on file. Cash is not king onboard. A picture of you will be taken so the ship’s crew knows what you look like, and you will be issued a keycard that becomes your stateroom key and onboard charging card.

Some guests buy keycard holders that they place around their necks. The keycards are about the size of a credit card. Some ships issue for free a nice keycard holder that securely holds the keycard with two extra slots, one of which may contain a simple ship’s deck plan, a graphical layout of the ship by deck that shows major features of the ship. This can also be easily carried in a pocket or fanny pack. Deck plans are posted by elevators and throughout the ship to show you where you are and help find your way.

That keycard is literally all you have to carry with you on the ship. You will also carry it with you when you go ashore, as the ship’s security officers will scan your keycard when you leave and come back aboard. That is how they track passengers and know everyone has gotten back on board. The keycard will also have your name and folio number (your onboard accounting file), lifeboat assignment and/or “Muster Station” – where you go in case of a declared ship-wide emergency. It is also used by the crew to verify your presence at the Muster Station and lifeboat area in drills or a real emergency.

Once you are physically on the ship there may be a period of time that you have to wait to access your stateroom. In all likelihood a whole ship full of passengers left earlier in the day – known as disembarkation for them – and the stateroom attendants have to clean and prepare the staterooms for you by changing the bedding, replacing towels and bathroom necessities, cleaning, vacuuming and making sure everything is shipshape for you. This can take hours. There will be places on the ship where you can wait and get something to eat. This is a good time to pull out that provided deck plan and get an idea of where your stateroom is located. It will be on a specific deck with a unique stateroom number. A ship-wide announcement will be made over the public announcement system when guests can go to their staterooms.

In your stateroom there will be a ship’s schedule that is published every day on your voyage. Make sure you read it thoroughly and keep it available during the day. This is a vital tool to know what is going on aboard the ship. The hours of operation for the restaurants, bars, various shops and facilities such as the spa, gym and medical center are provided, as are the numerous entertainment and enrichment activities onboard. There are also important telephone numbers listed.

Before the ship can sail a mandatory lifeboat drill must be conducted under the provisions of the Safety of Life at Sea (SOLaS). You will be instructed as to what you must do, and this is mandatory. The crew at each Muster Station will check for 100% attendance using keycards, and if you fail to show your name and/or stateroom number will be called over the ship-wide public announcement system until you are accounted for. These drills usually take about an hour.

The ship will get underway at a designated time and will host a gala event topside if the weather allows, usually with drinks, music and great all-around fanfare. You are finally on your way!

© Springer Nature Switzerland AG 2018

Gregory I. RedfernCruise Ship Astronomy and AstrophotographyThe Patrick Moore Practical Astronomy Serieshttps://doi.org/10.1007/978-3-030-00958-8_2

2. Big Bang to Homo Erectus to Multi-Messenger Astronomy

Gregory I. Redfern1  

(1)

NASA JPL Solar System Ambassador , Ruckersville, VA, USA

Gregory I. Redfern

If the title of this chapter doesn’t quite make sense to you it will after you have read the chapter. Now that you have committed to a cruise with an astronomy/astrophotography element it would be to your advantage to learn something about astronomy – the science that studies the universe. By doing so you will gain a deeper appreciation and understanding of the sky sights you will see and photograph. After all, astronomy is recognized as the oldest of the sciences and has a direct lineage from ancient astrology, where practitioners observed the sky to foretell the future. After reading this chapter and the others on specific astronomy and sky-related topics you will have a working knowledge of the concepts and structures of the universe.

It has been noted by historians of astronomy and anthropologists that each civilization and its culture that has inhabited Earth tried in some measure to understand the heavens and Earth. Each developed its beliefs as to what the lights in the sky were, some of which were observed to move in carefully observed patterns, and deified what we know to be the Sun, Moon and the five visible planets, Mercury, Venus, Mars, Jupiter and Saturn. Each used the heavens for its own purposes and legends, sometimes passing these along to history in some form or other. A common thread among humanity’s progression throughout the ages is that each civilization invested its treasure and used its cranial capacity to try and understand the heavens.

It was famously written in 1676 by Sir Isaac Newton (1643–1727), inventor of the calculus and the laws of motion, “If I have seen a little further it is by standing on the shoulders of Giants.” The generally accepted interpretation of Newton’s comment – he wasn’t the first to use it but was certainly the most famous to do so– is that he was guided by the scientific discoveries of those who preceded him. This is certainly true in all scientific endeavors, but in astronomy, unlike chemistry or biology, you can personally witness the results of our discoveries about the universe with your own eyes – the motions of the Solar System, seeing galaxies, knowing what powers the Sun and stars, seeing and hearing the ancient remnants of the Big Bang explosion that astronomers believe started it all on a vacant channel’s “snow” on your TV set.

The essential progression of our knowledge of the universe was from using just our eyes to ultimately using telescopes, computers, spacecraft and giant physics experiments to probe the depths of the very large and the very small. Our distant ancestors, Homo erectus, are thought to have evolved about 2 million years ago on the plains of East Africa, going from all fours to upright with a significantly larger cranial vault. They had to notice the Sun, Moon and other lights in the sky. We will probably never know what they thought of what they were seeing in the sky, but it is likely that they did in fact see and wonder about them.

When you look up at the sky you always see the Sun, Moon, planets and stars rise in the East and set in the West. The prevailing view in the earliest civilizations about Earth and the sky above was that the sky and all it contained revolved around Earth. Earth was the center of the universe or heavens. Intuitively it made sense, as everything in the sky moved, and Earth stood still; there was no perception of motion. This view was put forth by the Greek philosopher and scientist Aristotle (384–322 b.c.) and was known as the geocentric universe. Aristotle’s view prevailed as the true nature of the universe for nearly fifteen centuries. Earth and humans were the center of the universe and supreme. The heavens above were immutable and perfect.

The Greek astronomer Aristarchus (310–230 b.c.) made what are thought to be the first measurements of the size and distances of the Sun and Moon. He used geometry and his observations of total lunar eclipses for his calculations. Although his calculations were not very precise by today’s standards, the means by which he made them indicated that he understood the workings of the Solar System. To him, Earth had to revolve around the Sun.

Earth was thought to be flat by some civilizations. But for 2000 years humanity has known our planet is spherical, due to the Greeks using the curvature of Earth’s shadow during lunar eclipses as proof that Earth was round and not flat. Eratosthenes (276–195 b.c.) also calculated Earth’s diameter using geometry and measuring the Sun’s shadow on the summer solstice. He also measured the tilt of Earth’s axis as being 23.5 degrees.

It was the Greek astronomer and mathematician Ptolemy (a. d. 100–170) whose influential treatise, the Almagest , published in 150 a. d., solidified the geocentric view for so many years. The Almagest and its thirteen chapters described the workings of the universe and provided a physical description of how the heavens moved. He was able to calculate when lunar and solar eclipses would occur (see Chap. 10) and predict the positions of the planets using his Ptolemaic system.

At the beginning of the sixteenth century the geocentric view was running into serious issues, not least of which was its inability to help mariners navigate on their great voyages of exploration to America and the Far East. The heliocentric universe started to emerge due to the theories of Nicolaus Copernicus (1473–1543) in 1515. He was a physician, lawyer and church administrator who did astronomical research in his spare time.

The result of his work was the De Revolutionibus Orbium Coelestium (“On the Revolutions of the Celestial Orbs”). Copernicus did not publish this until 1543, shortly before his death. Some scholars believe he was afraid to publish it for fear of ridicule or that the Catholic Church would disapprove.

De Revolutionibus Orbium Coelestium was widely viewed as a work comparable to the Almagest. But geocentrism held sway among astronomers for over a generation, in part due to the fact that physics at the time could not explain the natural world other than the way it had always been viewed. There was also fear of religious persecution for heretical teachings. Heliocentrism ran counter to many Biblical passages, which also contributed to its rejection. Copernicus had dedicated De Revolutionibus to Pope Paul III, and the book was not a significant issue for the Church itself until after the turn of the century.

Visual observations of the sky using an assortment of astronomical instruments to measure positions and angles of the stars and planets reached its zenith with the Danish astronomer Tycho Brahe (1546–1601). Observations using instruments designed, built and calibrated by Brahe were the most accurate in the world at the time and were comprised of years of data accumulated at his numerous observatories. He was the first to record observations of the planets and Moon throughout their orbits instead of just doing so at certain key points. Because of this he found orbital anomalies that had never been noticed before. Brahe also ran a printing press and published his major works. Ironically he never published his astronomical observations, but as we shall see they were fundamental to one of the most significant discoveries in astronomy.

Brahe’s observations of comets (see Chap. 12) and a “new star,” or supernova (see Chap. 6), made it clear that these objects were beyond the Moon. The absolute unchanging nature of the heavens as espoused by Aristotle was shown to be not so by these observations. Brahe’s observations of comets also showed that they moved through the heavens – another direct contradiction of Aristotle’s view of the universe. This discovery led to the eventual abandonment of the material celestial spheres, which were tightly bound to each other for millennia.

History records that in spite of all his observations and their subsequent effect on our understanding of the heavens, Brahe did not subscribe to a heliocentric universe as proposed by Copernicus. Brahe, like others, could not move past the physics of Aristotle that established an Earth-centric reality. Ironically it was Brahe’s own observations that would lead to the establishment of a heliocentric universe.

Johannes Kepler (1571–1630) was a prominent mathematician who was also interested in astronomy. One of his professors during graduate studies was a believer in the Copernican theory and as a result Kepler professed to be a “Copernican.” In 1597 he published his first major work, The Cosmographic Mystery, in which he declared that the distances of the six planets from the Sun (a heliocentric system) were determined by the five regular Platonic solids. He proposed that a planet’s orbit was circumscribed about one solid and inscribed in another. With the exception of Mercury – always a troublesome planet with regard to its orbit, as we shall see – Kepler got very accurate results.

His work so impressed Brahe that at the age of 27 Kepler was hired as Brahe’s assistant. His primary duty was to determine the orbits of the planets using Brahe’s observations. Brahe was not totally forthcoming in providing of all of his observations to Kepler, perhaps to prevent him from using them to prove heliocentrism. When Brahe died in 1601 Kepler took his place and gained access to all of his observations. Using his considerable mathematical talents Kepler tried to fit the planetary orbits into perfect circles, which he thought, like others before him, reflected the purity of the heavens.

Kepler eventually realized in his work on the orbit of Mars that it was an ellipse and not a circle that described the orbit of planets. He developed his Three Laws of Planetary Motion, the first two in 1609 and the third in 1619. Kepler did not know why the planets moved the way they did, but astronomers could now predict with excellent accuracy the motions and positions of the planets. Kepler’s Three Laws of Planetary Motion are a hallmark in the history of astronomy and would profoundly influence the future work of Sir Isaac Newton . Physics was about to finally break free of the age of Aristotle and undergo a monumental transformation that would become the basis for physics as we know it today.

One of the most influential physicists and astronomers in history, Galileo Galilei (1564–1642), made profound scientific observations of his numerous experiments involving motion and used his telescopes to view the heavens. He is often considered the founder of modern science, especially in physics and astronomy. Galileo revolutionized astronomy because he transformed it from being a pursuit confined to men’s philosophical interpretation of what their eyes showed them into a true science based upon observations and physical laws.

The Dutch had invented the “spyglass” in 1608 to get closer views of distant objects. Galileo’s genius in 1609 was to make his own instruments – telescopes – and use them to observe the heavens. The telescope led the way for the invention of other scientific instruments, and its evolution continues to this day in Earth- and space-based telescopes. The telescope was also the first scientific instrument to extend one of humanity’s senses – vision – to beyond everyday experience.

Galileo was not the first to use a telescope to observe the Moon or the Sun; that was accomplished by Thomas Harriot (1560–1621) in 1609 and 1610, respectively. Harriot never published his observations. Galileo did, thereby assuring his place in history (Fig. 2.1).

Fig. 2.1

Galileo telescope exhibit at the National Air and Space Museum. (Image by the author)

At the age of 45 Galileo embarked on a systematic series of astronomical telescopic observations beginning with the Moon on November 30 to December 19, 1609; Jupiter on January 7 to 15, 1610; fixed-star formations February 1610; Saturn in July 1610; Venus in December 1610; and sunspots in 1611.

Through these observations Galileo transformed the Moon from a perfectly smooth spherical body into a physical world similar to Earth, where he saw valleys, plains and mountains, and what he thought might be seas in the flat, dark terrain. Jupiter had four small “stars” (which Galileo quickly realized were moons) that orbited the planet; Saturn appeared to be a three-star object with the largest “star” in the center and a smaller one on each side, and they never moved in relation to one another. Venus exhibited phases that mimicked those of the Moon, the Sun had imperfections in the form of black spots, and the Milky Way had innumerable stars. Orion, Cancer, the Pleiades and murky areas of the sky called nebulae (Latin for clouds) revealed previously unseen stars in these regions.

The heavens certainly weren’t as unchanging and perfect as postulated by Aristotle. His observations of Jupiter and Venus convinced Galileo that the planets orbited the Sun as envisioned by Copernicus almost a hundred years earlier. In the middle of March 1610 Galileo published his discovery of the moons of Jupiter, and his observations of the Moon and the fixed stars in his book Sidereus Nuncius (The Starry Messenger). The book made Galileo famous and led to prestigious appointments. Galileo received public support for his work from none other than Kepler in an open letter published in April 1610 and independent confirmation of Galileo’s work by Kepler in August 1610.

Galileo continued his astronomical observations, including comets and studies of using the timing of eclipses of the moons of Jupiter to determine longitude at sea – which was deemed too impractical for use. He ran afoul of the Catholic Church for his views supporting Copernicus’s theory of a Sun-centric universe and faced the Inquisition. He was placed under indefinite house arrest at his villa in December 1632, where he lived out his remaining days, dying in January 1642.

The same year Galileo died the next iconic figure in the history of astronomy and physics was born, Isaac Newton (1642–1727). Newton’s accomplishments in science are many and include calculus, invention of the Newtonian reflecting telescope, and an improvement of the sextant for navigation at sea. But the highlight of his storied career was his publishing the Philosophiae Naturalis Principia Mathematica (“Mathematical Principles of Natural Philosophy”) in 1687. The Principia truly established science as we know it today and brought forth the death knell of physics and astronomy as envisioned by Aristotle and the generations that followed.

Stanford University’s Encyclopedia of Philosophy entry on Newton and the Principia are listed in the Appendix at the end of this book. The profound effect of the Principia on science as a whole, and astronomy in particular, is succinctly explained in the opening paragraph of the “Overview”:

Viewed retrospectively, no work was more seminal in the development of modern physics and astronomy than Newton’s Principia. Its conclusion that the force retaining the planets in their orbits is one in kind with terrestrial gravity ended forever the view dating back at least to Aristotle that the celestial realm calls for one science and the sublunar realm, another. Just as the Preface to its first edition had proposed, the ultimate success of Newton's theory of gravity made the identification of the fundamental forces of nature and their characterization in laws the primary pursuit of physics. The success of the theory led as well to a new conception of exact science under which every systematic discrepancy between observation and theory, no matter how small, is taken as telling us something important about the world. And, once it became clear that the theory of gravity provided a far more effective means than observation for precisely characterizing complex orbital motions – just as Newton had proposed in the Principia in the case of the orbit of the Moon – physical theory gained primacy over observation for purposes of answering specific questions about the world.

Gravity, discovered by Newton , became the force that determined the movement of the Moon and planets, which could be calculated using his universal law of gravitation (astronomy had not progressed yet to objects beyond our Solar System that could be observed and measured). But Newton did not know what caused gravity. That question would be famously explored in the beginning of the twentieth century.

Many discoveries in physics and astronomy took place in the eighteenth and nineteenth centuries. Telescopes got bigger and better which pushed the boundaries of observations by skilled observers beyond the known solar system and out into the stars and nebulae. Questions began to arise as to what the stars and these nebulae that populated the sky everywhere one looked really were. Spiral arms could be seen in some of the nebulae, which prompted the speculation that perhaps they were related to our Milky Way Galaxy. Other nebulae were elliptical in shape; some had a luminous appearance while others were dim.

Two major milestones during this time were the invention of astronomical photography and the spectroscope. According to Wikipedia’s entry on the history of astrophotography (https://​en.​wikipedia.​org/​wiki/​Astrophotography​):

The first-known attempt at astronomical photography was by Louis Jacques Mandé Daguerre (1787–1851), inventor of the daguerreotype process that bears his name, who attempted in 1839 to photograph the Moon. Tracking errors in guiding the telescope during the long exposure meant the photograph came out as an indistinct fuzzy spot. John William Draper (1811–1882), New York University Professor of Chemistry, physician and scientific experimenter managed to make the first successful photograph of the Moon a year later on March 23, 1840, taking a 20-minute-long daguerreotype image using a 5-inch (13-cm) reflecting telescope.

Astrophysics really came of age with the spectroscope. When attached to the telescope it became possible to photograph the spectrum of the astronomical object being studied to determine physical properties such as its temperature, composition, as well as measurements of its speed and whether it was moving towards the observer or away.

Munich optician Joseph Frauenhofer (1787–1826) discovered in 1814–1815 that when light from the Sun is allowed to pass through a slit and then through a glass prism (Newton had done experiments involving light and prisms), the resulting spectrum of colors is crossed with hundreds of dark lines. These dark lines were always found with the same colors and with each corresponding to a definite and measurable wavelength of light. Frauenhofer determined that these same dark lines were in the same positions as the spectrum of the Moon and brighter stars. Astronomers came to realize that each line (now known as Frauenhofer lines) is due to the absorption of light by a specific chemical element. Astronomers could now, for the first time, determine that the elements on the Sun and the stars themselves are the same as those found on Earth. This was a huge leap in our understanding of the universe, as it showed a common composition of the astronomical objects we observed with elements here on Earth.

Have you ever heard the sound of a siren as it approached you and then started to move away? As the siren got nearer you could hear it change its pitch. It increased and then would start to decrease as it got father away. This happened because the sound waves did not have to travel as far to reach you as the siren approached and conversely had to travel farther as the siren sped away. Johann Christian Doppler (1803–1853), a professor of mathematics, discovered in 1842 that this process, which bears his name, the Doppler effect, was the same for light waves. Light from stars moving towards Earth would be shifted towards shorter wavelengths (blue shift), while the light from stars moving away would be shifted towards longer wavelengths (red shift). Doppler erroneously thought that this explained why stars had blue and red colors – they were either moving towards or away from us – but as we shall see this was not the case.

In 1868 Sir William Huggins (1824–1910) discovered that the dark lines in the spectra of some of the brighter stars were shifted slightly to the red or the blue when compared to the normal position of these dark lines in the spectrum of the Sun. He attributed this to being caused by the Doppler effect. In the coming decades the Doppler shift would be pivotal in the study of the Sun, Solar System, stars and the nature of the universe itself.

Spectroscopy and astrophotography evolved, and in the early twentieth century were as much an art as a scientific technique (Fig. 2.2).

Fig. 2.2

Spectroscope used on the 200-inch on display at the National Air and Space Museum in Washington, D.C. (Image by the author)

Early on astronomers had to insure their photographic plates for spectroscopy and astrophotography were properly prepared – a uniform silver coating with no imperfections – sealed in a tight light box for transport to and from the plate holder. In complete darkness the plate had to be loaded into the spectroscope or photographic plate holder and the telescope pointed precisely to the proper object.

When the plate was opened to the incoming light the astronomer had to make sure that the plate remained centered, or blurring would occur, ruining perhaps several nights of exposure time. This was physically and mentally demanding, as the astronomer would have to guide the telescope by peering into a dimly lit guiding eyepiece with crosshairs centered on a guide star or the object itself while using a control box to move the telescope in order to keep it properly centered.

The observatory was open to the night sky, so cold temperatures might be present for hours on end, and the astronomer couldn’t move his eye from the guiding eyepiece. When the observing run was completed the plate had to go back in the box, and in the dark room be removed and properly developed. If all had gone well in this arduous process the end result would be a plate for study and archiving. One has to truly admire these pioneers for their skills, endurance and end results.

At the beginning of the twentieth century, 1900 to be exact, astronomers did not know the answers to these questions:

What is gravity?

What powers the stars and the Sun?

What is the speed of light?

Is the Milky Way the only galaxy and what is the full extent of the universe?

Are the “spiral nebulae ” part of the Milky Way Galaxy or are they galaxies in their own right?

Were there more than eight planets in the Solar System?

By 1930 not only had these questions been answered and a ninth planet found, but the most astounding discovery to date about the universe – that it was expanding – was announced in 1929. More about all of this in just a bit.

In addition to these questions concerning the universe at large and the discoveries that followed, physicists concurrently were exploring the world of the very small to determine how light and matter behaved on the atomic and subatomic scale. In 1924 quantum mechanics became the name of the branch of physics that dealt with such explorations. With all of the discoveries made in quantum mechanics it became readily apparent that the world of the very, very small influenced the world of the very, very large. Even today we are grappling mightily with the true nature of the quantum realm and the implications of its effect on the birth and ultimate fate of the universe. But it was the intertwined work of several scientists and astronomers early in the twentieth century that would have a profound and lasting influence on astronomy and the universe as we know it today and what we think it will be in the future.

Albert Einstein (1879–1955) published his Theory of Special Relativity in 1905 and later that year also showed, via arguably the world’s most famous equation, E = mc², that matter and energy are related – that the conversion of a small amount of mass into energy would produce an extremely large amount of it. This became a powerful clue as to what powered the stars. Einstein also published his Theory of General Relativity in 1916. By 1917 George Ellery Hale (1868–1938) had built the Mount Wilson Observatory with its 100-inch Hooker telescope. Due to discoveries made with the 100-inch telescope Einstein’s Theory of General Relativity was profoundly affected and had to be modified by him to correct the “greatest blunder of his career.” It is a tale worth telling.

Einstein’s decade of work on his Theory of General Relativity using very insightful “thought experiments” led to elegant equations that described what happens to space-time – the fabric of the universe – in the presence of matter as well as other aspects of the universe. Space itself becomes curved due to the presence of matter, and this in turn dictates how matter (people, stars, planets, galaxies) will move. Einstein’s equations were able to do what Newton’s could not – explain and compute the perihelion precession of Mercury’s orbit that had mystified astronomers for centuries. Einstein’s equations were also able to show that rays of light would be deflected from their straight path by a precise amount as determined by the amount of mass (matter) they encountered. This was historically proven during the total solar eclipse of 1919, when photographs taken of stars near the totally eclipsed Sun showed that they were offset by the precise amount predicted by Einstein’s equations. Einstein became an instant worldwide celebrity, and the General Theory of Relativity passed another rigorous test, one of many to follow, even to present day.

For all of its predictive power Einstein did not believe in one aspect of his Theory of General Relativity that the equations showed – that the universe was either collapsing or expanding. There within the equations he himself had created, others saw that the universe was expanding from its inception. But this flew in the face of the astronomical experience of the day, that the universe was static and, forgive the pun, relatively unchanging on the grand scale. In order to make his equations fit the prevailing astronomical view of the static universe Einstein inserted what he called the cosmological constant, a mathematical term that kept the universe from expanding or collapsing.

Alexander Friedmann (1888–1925) was a Russian/USSR mathematician and physicist who in 1922 put forth the idea of an expanding universe based on his work with Einstein’s General Theory of Relativity. He is credited as being the first to discover this possible result from Einstein’s equations.

Belgian priest and astronomer Georges Lemaître (1894–1966) saw that Einstein’s theory showed an expanding universe and published a paper in 1927 that stated as such. But because his paper was published in Belgium, it went virtually unnoticed by the astronomical community. At a physics conference held in Slovak in 1927 Einstein told Lemaître that the mathematics of his theory were correct, but his physics was essentially all wrong. A year later Lemaître pondered the implications for an expanding universe and put forth the incredible idea that it must have originated at a finite point in time. He reasoned that in an expanding universe it had to be smaller in the past, and if you were to go back in time you should come to a moment when all the matter in the universe was compressed into an extremely dense state.

Referring to the new quantum theory of matter that had been recently developed he argued that the universe was initially a single particle he called the “primeval atom .” Lemaître described this single particle as disintegrating in an explosion that subsequently gave rise to space and time and the expansion of the universe. As a result of his work Lemaître would eventually become known as the “Father of the Big Bang theory.”

The prevailing static view of the universe continued to exist until 1929, when a discovery made with the world’s largest telescope at the time changed our perspective on the universe forever. But before this could happen a great telescope had to be built.

George Ellery Hale was a gifted astronomer, primarily interested in solar astronomy. He discovered solar magnetism, but his accomplishments were many. Along with James E. Keeler (1857–1900) he established the prestigious Astrophysical Journal , which is still a premier publication 123 years after its founding. Hale was also instrumental in helping create what would become the International Astronomical Union (IAU) and bringing the world-famous California Institute of Technology (Caltech) into existence. But by far his greatest accomplishment was the building of the world’s largest telescopes in his day and their accompanying observatories.

The three observatories that Hale got built were the Yerkes Observatory in 1897, with its 40-inch refractor; Mount Wilson Observatory in 1917, with its 60-inch and 100-inch reflectors as well as solar observing towers of 60 feet and 150 feet; and finally Mount Palomar Observatory in 1948, with its 200-inch Hale telescope. Each of these observatories explored the universe and made significant contributions to astronomy, but it was the 100-inch Hooker reflector telescope that brought forth a whole new universe due to the observations of two astronomers, Edwin Hubble (1889–1953) and Milton Humason (1891–1972).

Hubble, using the 100-inch telescope, discovered in 1923 that the mysterious spiral nebulae , thought by some to be part of the Milky Way Galaxy, which in turn was thought to be the whole universe at the time, were in fact other galaxies like ours. He proved this conclusively by observing a type of star called a Cepheid variable in a spiral nebula then called the Andromeda Nebula. On October 6, 1923, an historic photographic plate Hubble made of the Andromeda Nebula showed what he originally thought was a nova (see Chap. 6) along with two other novae. Based on follow up observations that showed this star was in fact a Cepheid variable star and not a nova, he crossed out the “N” designation and called it “V-1” for variable.

Because Cepheid variables were observed in our own galaxy and found to vary in their brightness over a very precise and reoccurring period of time it was simply a matter of measuring the brightness of V-1 and computing the difference in its brightness from those in our own galaxy. The difference in brightness would be a direct result of the distance the star, and in turn the Andromeda Nebula, was from Earth. Hubble computed the distance to be about a million light years (ly). Even though his calculated distance was incorrect – the modern value is 2.5 million light years – it proved that the Andromeda Nebula was in fact a galaxy separate from our own. The universe instantly became populated with thousands of galaxies beyond the Milky Way.

Hubble went on to observe many galaxies with the 100-inch telescope, and in 1926 developed a classification scheme for galaxies (see Chap. 7) that astronomers still use today with modifications. Also, with the crucial assistance of Milton Humason, he measured the distances to several of these galaxies by calculating their red shifts.

Milton Humason was a high school dropout at age 14 living in Los Angeles. He had a job taking tourists up to Mount Wilson, and when construction started on Mount Wilson Observatory he got a job as a mule team driver taking loads up the mountain. Humason got a step up in life by becoming a janitor at the observatory, which allowed him to know astronomers and most importantly Hale. Humason so impressed Hale that he got him a job at the observatory as a night assistant, a technician who helped the astronomer make observations with the telescope. Humason was surprisingly good with the telescope and showed he had a real affinity for astronomy, so Hale much to the chagrin of the established and astronomical elite of the staff – promoted him to an assistant astronomer position. It was here that Humason really excelled and developed the necessary techniques to photograph and measure the red shifts of the observed galaxies using the 100-inch telescope.

Together, he and Hubble made these observations and measurements that stunningly proved in their historic paper published in the Astrophysical Journal in 1929 that the universe was expanding. Simply stated in what became known originally as Hubble’s law, the farther away a galaxy is the faster it is moving away. This discovery was perhaps the greatest in the history of astronomy to date and forever altered our view of the universe. It also proved that Einstein’s original General Theory of Relativity was correct, as was Lemaître’s (and others) work. Einstein had to modify his theory by removing the cosmological constant (more on this later), and by 1930 an expanding universe was generally accepted. The IAU voted in October 2018 to change Hubble’s Law to the Hubble-Lemaître Law to refect the contributions of Lemaître to modern cosmology.

In 1931 Einstein visited Pasadena, California, home of the administrative offices of Mount Wilson Observatory and partially constructed Mount Palomar Observatory. He met Hubble and Humason as well as other members of the staff and went up to the mountain to see the telescope that changed the universe and his theory. There is a famous photograph of Einstein looking through the eyepiece of the 100-inch telescope with Hubble and others looking on. Einstein was probably not really looking through the eyepiece. If he had his night vision would have been painfully disrupted.

One other historically significant and prescient series of observations made by Swiss astronomer Fritz Zwicky (1898–1974) with the 100-inch telescope centered on the Coma cluster of galaxies . His observations of the motion of galaxies within the Coma cluster revealed that on average they were moving too fast for the Coma cluster to be held together by the amount of matter visible.

Zwicky published a paper in 1933, and according to a March 2013 online Swiss Physical Society article, “Fritz Zwicky: An Extraordinary Astrophysicist,” by Norbert Straumann and Uni Zürich, (Original source: “SPG Mitteilungen” Nr. 39, März 2013, pp. 22–24, followed by the article at https://​www.​sps.​ch/​en/​articles/​history-of-physics/​fritz-zwicky-an-extraordinary-astrophysicist-6/​) Zwicky wrote the following: “In order to receive an average Doppler effect of 1000 km/s or more, which is what we have observed, the average density in the COMA system would have to be at least 400 times greater than that of visible matter. If this can be shown to be the case, then it would have the surprising result that dark matter is present in the Universe in far greater density than visible matter.”

Zwicky’s observations were rough estimates, but they have withstood the test of time. The notion that there was more matter in galaxies than we could see was confirmed later in the 1970’s by the work of Vera Rubin (1928–2016) on the orbital velocities of individual stars in the Andromeda Galaxy and other spiral galaxies. Her observations showed that stars in the outer margins of the Andromeda Galaxy and others were orbiting almost as fast as those near the center of the galaxy, a clear violation of Newton’s laws of gravitation. It was as if Pluto orbited the Sun as quickly as Mercury. The prevailing and almost universally accepted way this is thought to be possible is that there is far more unseen or dark matter in the outer halo of the galaxy. We’ll return to dark matter later in the chapter.

By the time Palomar Observatory was completed in 1948 with the 200-inch Hale telescope becoming the world’s largest and pushing the visible boundaries of the universe ever farther back in time, most astronomers accepted Lemaître’s ideas about how the universe came into being. In 1933, during lectures being given by Lemaître and Einstein in California at the California Institute of Technology, history records that Einstein stood up clapping and commented after hearing Lemaître’s theory on the beginning of the universe that, “This is the most beautiful and satisfactory explanation of creation to which I have ever listened.”

The hardest part of Lemaître’s theory of the universe for astronomers to comprehend initially was that it was finite, i.e., it had a beginning and was not infinite. Even though Lemaître’s theory gained widespread acceptance it was the British astronomer Fred Hoyle (1915–2001) who disdainfully called it “the Big Bang” in 1950. The name stuck, and the event is now universally known as such.

As with all theories, there had to be accompanying evidence in the form of data, observations and experimental results to prove whether the Big Bang was correct. A really important piece of evidence was found literally by accident by two Bell Laboratories radio astronomers in 1964. Robert Wilson (1941-) and Arno Penzias (1933-) were operating a horn antenna radio telescope in Holmdel, New Jersey, that had completed its work with NASA on telecommunications projects involving the Echo satellite (Fig. 2.3).

Fig. 2.3

Horn antenna that detected evidence of the Big Bang. (Image by the author)

They went about calibrating their radio telescope by making observations of radio signals across the sky from their location. It appeared that the telescope had a persistent hiss that remained constant no matter where they pointed the telescope. The duo inspected the interior of the horn antenna and found that a family of pigeons, complete with all of their droppings, had taken residence in the telescope. They used a trap to capture the pigeons and remove them (Fig. 2.4).

Fig. 2.4

Pigeon trap used by Wilson and Penzias on display at the National Air and Space Museum in Washington, D.C. (Image by the author)

They also cleaned out all of the pigeon-related leavings, sealed the seams of the interior of the telescope and did whatever they thought would reduce or eliminate the hiss (Fig. 2.5).

Fig. 2.5

Interior view of the horn antenna. (Image by the author)

It didn’t work, as this all-sky hiss persisted. They also calculated that the hiss had an equivalent temperature of only 3 degrees Kelvin (K) above absolute zero (−273 degrees Celsius, or −459 degrees Fahrenheit).

At the same time and just down the road at Princeton University, a team of physicists led by Robert Dicke (1916–1997) had been working on finding evidence for the Big Bang theory. Dicke surmised that if the Big Bang theory was correct, in that there had been an initial explosion that created the universe, there should be a residual remnant of the fireball that started it all. Given the expansion of the universe, which was pretty well known by Dicke and other Princeton physicists, especially a young theorist named P. J. E. Peebles (1935-), they calculated that the leftover fireball of the Big Bang should be observable in microwaves as a persistent hiss visible to radio telescopes. The temperature that the Princeton group thought would be observable was about 10 degrees K. Dicke and his colleagues had begun preparations to build such a detector.

Penzias and Wilson were not aware of the latest cosmological theories about the Big Bang but happened to know colleagues that were. Dicke and his team had put forth their ideas about the hiss of the Big Bang and how they were going to go about trying to detect it, and Peebles had been giving lectures on his work as well. Penzias and Wilson eventually met with Dicke and showed him the results they had obtained with the horn antenna telescope. History records – even via a Twitter tweet from a famous physicist/cosmologist – that Dicke stated to his team, “Well, boys, we have been scooped.”

Penzias and Wilson had found the microwave radiation hiss that represented the remnant of the Big Bang. Penzias and Wilson published in the Astrophysical Journal their radio telescope results as a letter, with an accompanying letter by Dicke and his team explaining the cosmological implications of the discovery. Penzias and Wilson won a portion of the 1978 Nobel Prize for their discovery (Fig. 2.6).

Fig. 2.6

Horn antenna national landmark. (Image by the author)

This was a huge vindication of the Big Bang, as it showed that an initial explosion had taken place billions of years ago and an expanding universe had red-shifted the light of that event into what became known as the cosmic microwave background, or CMB.

What astronomers wanted now was to map the CMB across the entire sky, and to do that they had to go into space. Two astronomers led the efforts to build a spacecraft that would do precisely that – George Smoot (1945-) and John Mather (1946-). In 1989 the Cosmic Background Explorer (COBE) satellite was launched. Almost immediately after it was in space it measured the CMB to a temperature of 2.753 K and proved that it was from the Big Bang. COBE also mapped the CMB in 1992 and discovered minuscule temperature variations on the order of millionths of a degree dispersed throughout the CMB.

Scientists attributed this to variations in the CMB caused by the gravitational clumping of matter, which affected densities and temperatures. Some scientists also thought that gravitational waves , which we will discuss shortly, could have caused some of the differences observed. The bottom line was that COBE was another strong piece of evidence for the existence of the Big Bang. Smoot and Mather received the 2006 Nobel Prize for their pioneering work.

Two other spacecraft added to our knowledge of the Big Bang, the Wilkinson Microwave Anisotropy Probe (WMAP) in 2001 – more on this mission later – and the European Space Agency’s Planck mission, which launched in 2009 and was turned off on October 23, 2013. The last Planck official data release occurred on July 17, 2018.

Planck represents our most precise observations to date of the Big Bang CMB. We will learn more from the remnant light of the Big Bang as new analytical techniques are developed that can glean data that resides within, especially from gravitational waves , which we will discuss shortly.

As the Big Bang was becoming accepted as having been a real event, astronomer Vera Rubin was making observations of the individual stars of galaxies. She and her colleague Kent Ford (1931-) were noticing a very perplexing pattern. The orbital velocities of stars located in the outer boundaries were way too high for the amount of matter present. According to the well-known laws of gravitation astronomers could calculate the expected orbital velocities of individual stars in galaxies by measuring their orbital velocities against the amount of mass present in the galaxies. By 1978 the work of Rubin and Ford, showing that up to 90% of the matter in the galaxies was unseen, became widely accepted. But, as we shall see with dark energy, dark matter remains a mystery as to what it truly is.

In 1998 two independent teams of astronomers announced the results of their high red shift (and therefore far away) supernova (see Chap. 6) survey using the Hubble Space Telescope (HST) as well as ground-based telescopes. Supernovae were used because astronomers knew their very bright light output to a high degree of precision, and just like Hubble did with the Cepheid variable star located in the Andromeda Galaxy, they used this as a means to calculate the distance to the supernova’s host galaxy. The distances involved billions of light years, much farther than had been previously observed.

The teams had used supernovae located at great distances to measure their red shift and in turn calculate their host galaxy’s speed of recession, which would in turn determine the value known as the Hubble constant – the rate at which the universe is expanding. The teams had expected to get a far more precise value of this important number, which states how fast the universe is expanding and shows that the expansion of the universe is slowing down due to the effect of gravity. But their results were simply astounding and turned the astronomical world upside down.

What both of these teams found was that the universe was accelerating in its expansion, which was believed to be caused by what came to be called dark energy. This was a completely unexpected result, and team leaders were awarded the 2011 Nobel Prize in Physics as a result. Instead of determining a more precise value for the expected slowing of the expansion of the universe it was discovered that some negative pressure component in the universe – dark energy – was at work. Further observations were conducted using supernovae, which reinforced the original findings of the two supernova survey teams.

A major factor in convincing astronomers about dark matter and dark energy was NASA’s Wilkinson Microwave Anisotropy Probe (WMAP) mission, which was to make fundamental measurements of cosmological parameters by studying the properties of our universe as a whole. WMAP was stunningly successful over its nine-year lifetime. Here are some of the findings from WMAP posted online at NASA’s WMAP Top Ten results:

Mapped the pattern of tiny fluctuations in the cosmic microwave background (CMB) radiation (the oldest light in the universe) and produced the first fine-resolution (0.2 degree) full-sky map of the microwave sky.

Determined the universe to be 13.77 billion years old to within a half percent.

Determined that ordinary atoms (also called baryons) make up only 4.6% of the universe.

Completed a census of the universe and found that dark matter (matter not made up of atoms) is 24.0%.

Determined that dark energy, in the form of a cosmological constant, makes up 71.4% of the universe, causing the expansion rate of the universe to speed up.

“Lingering doubts about the existence of dark energy and the composition of the universe dissolved when the WMAP satellite took the most detailed picture ever of the cosmic microwave background (CMB).” (Science Magazine, 2003, “Breakthrough of the Year” article.)

Because of the WMAP spacecraft, by 2003 dark energy and dark matter were generally accepted as being real. But back then, as it still is today, the nature of what dark energy is, just like dark matter, remains elusive. One train of thought is that dark energy is the manifestation of Einstein’s cosmological constant, that factor he added in to his General Theory of Relativity equations to keep the universe from collapsing or expanding. If true, this would mean that space-time itself has an inherent property, a force that is at work on the universe as a whole.

Astronomers have determined that this acceleration began roughly 7 billion years after the Big Bang. It was at this time that the universe had expanded to the point where the density of the matter in the universe, and hence the gravity present was no longer able to offset dark energy. The universe began to accelerate in its expansion.

There are other primary theories about the universe that remain active today, namely inflation, string theory and multiverses. But these are beyond the scope of this chapter and book. These topics require very lengthy explanations and can be pursued by you if you wish, as we have included some suggested reading and Internet sites for readers who want to explore these complex but vital theories.

The last astronomical topic of this chapter is the most current as well as one of the most exciting – gravitational waves (GW). Gravitational waves are ripples or distortions in the fabric of space-time that were predicted by Albert Einstein in his Theory of General Relativity in 1916. GW are caused by massive objects moving with extreme accelerations and involve events like the merger of black holes and neutron stars (see Chap. 6). In comparison Electromagnetic waves are the result of vibrations produced by electric and magnetic fields that propagate through space that we see as light and radiation.

All of the information astronomers have ever received from the universe (except for specific Solar System spacecraft missions and landings and meteorite recoveries) has been in the form of electromagnetic waves. That all changed on September 14, 2015, when the first gravitational wave s were observed due to the merger of two black holes (see Chap. 6), with the event being announced by the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo collaborations on February 11, 2016. This opened a whole new way to explore the universe, including what many believe will be the eventual detection of gravitational waves in the primordial fireball of the Big Bang itself.

But it was the merger of two neutron stars (see Chap. 6) on August 17, 2017, that inaugurated a whole new era of astronomy – the Multi-Messenger astronomy era. On that date gravitational waves were detected by LIGO and Virgo, followed just two seconds later by weak energy gamma rays picked up by NASA’s Fermi spacecraft Gamma-ray Burst Monitor. That same evening teams of astronomers, using ground-based telescopes, reported a new source of optical and infrared light in a galaxy located about 130 million light years from Earth. NASA’s Chandra X-ray Observatory spacecraft did not detect any X-rays from this gravitational wave source initially, but it did a week later. Eventually all of these observations were correlated to the source of the gravitational waves – a kilonova (see Chap. 6).

Never again would light alone be the sole source for our explorations of the universe. Multi-Messenger astronomy has now been added to our toolkit as we try to further build our understanding of the universe and our place in it.

Humans are building ever better and larger ground- and space-based telescopes with sophisticated instruments, larger and faster supercomputers, and ever more sensitive wave and particle detectors. We have much more to discover and learn about the universe.

Think about this as we finish this broad brush look at humanity’s progression of understanding the universe. Our ancestor, Homo erectus, roamed the plains of Africa, Europe, China and Indonesia starting 2 million years ago. They stood upright and walked/ran large distances, practiced socialization by caring for the weak and elderly, built campfires and used stone tools. They had increased cranial capacity, which helped them survive and thrive. In a word, we modern humans – Homo sapiens – are just an updated version of them.

It is hard to believe that none of them looked at the Sun, Moon and the wandering lights in the sky (planets), all of which are essentially unchanged today from their time. The Moon would have been only 31 miles closer to Earth back then. Some of the stars in the night sky would have appeared in different positions, and the North Star would not have been Polaris. Most, if not all, of today’s constellations would not have been recognizable to us.

As our ancestors huddled together for warmth and protection at night, perhaps by the fire or out on the plains with no light pollution, the sky would have been awash with stunning vistas, especially the Milky Way during the warm summer months. They simply could not have avoided seeing it. What, if anything, did they think about what they saw? We will probably never know if language was part of their world, but one of them could have simply pointed up to the sky for others to see.

The span of the astronomical timeline we have discussed in this chapter covers only 24 centuries, or 2400 years. That is 1.2% of the 200,000 years Homo sapiens have been on Earth. It is only 0.12% of the 2 million years that Homo erectus dominated Earth, a mere pittance in the history of humanity. We twenty-first century humans lack an appreciation for our past roots and the 4.6-billion-year history of our planet. We tend to believe that we have dominated Earth forever. As you can see this is not the case, and we are the new kids on the block. But we have come far in our pursuit of knowledge about the lights in the sky and our place in the universe. We have definitely stood on the shoulders of giants, if not our human ancestors, to get to where we are today.

We humans, all life on this planet, our Sun and our Solar System are all directly connected to and evolved from the universe. As you sail the seas and oceans you will blend their allure and beauty with the photons you capture from the sky above through your astrophotographs. Never lose the connection to our past, and always appreciate the hope that comes with the future.

Let’s get started….

© Springer Nature Switzerland AG 2018

Gregory I. RedfernCruise Ship Astronomy and AstrophotographyThe Patrick Moore Practical Astronomy Serieshttps://doi.org/10.1007/978-3-030-00958-8_3

3. Using Your Ship-Observatory at Sea

Gregory I. Redfern1  

(1)

NASA JPL Solar System Ambassador, Ruckersville, VA, USA

Gregory I. Redfern

Getting Familiar with Your Ship

The moment has finally arrived. You have gone through the check in process on the pier and you are now about to get your first glimpse of the place you will be calling home and using as an observatory for the duration of your cruise. Once you go up the gangway, the stairs from the pier to the ship’s entryway, you will actually set foot on the ship herself. Ship security personnel will scan your keycard, and you will officially become part of the ship’s roster. From here on out you have to learn your way around the ship, and her deck plan is your guide.

Ship Tip

Prior to leaving for the ship you should spend some time familiarizing yourself with the ship’s deck plan, which is available on the cruise line’s website. You might even consider downloading a copy of the deck plan to take with you, although most ships provide a pocket-size deck plan that fits in the (if) issued keycard holder. Every ship, even of the same class, is different. Please note that even if you were previously on a ship she may have undergone a modernization or an upgrade that changed her deck plan. Bottom line – learn the deck plan. You’ll be glad you did.

Your first shipboard task will be to find your stateroom using the deck plan. But first you have to determine if the staterooms are available for occupying. You have to realize that another whole set of guests left the ship the day you came aboard, and the stateroom attendants have to get the staterooms ready for the arrival of new guests, not a minor task. You can inquire with the ship’s security as you check in or at the reception desk. If the staterooms are not ready you can start familiarizing yourself with the ship – or maybe you will want to get something to eat and drink. When asking about your stateroom, you can inquire if the ship is serving food and where.

The deck plan will provide the layout of the ship for each deck that passengers have access to. You will learn the location of your stateroom, the dining room(s), spa, fitness center, pool(s), medical bay, library, reception, shore excursions office, theater, casino – all of the facilities and locations that make cruising great. The ship’s deck plan on the website or your printed out copy gives you an overhead view of each deck, with a side view of the vertical layout of the decks.

On board ship, usually by the elevators, each deck of your ship will have a side view deck layout with an outline of the ship that shows your location and all of the decks. The facilities located on each deck will be listed as well as stateroom numbers . The deck plan will also provide a listing of the various facilities and what deck they are on. Your location where you are viewing the deck plan will be indicated by a red dot “You Are Here” – sort of an X marks the spot. To get to where you want to go you find out what deck it is on and take the elevator or stairs to the required deck. Once on the specific deck you can consult the deck plan and find out if you need to go forward (towards the bow or front of the ship) or aft (towards the stern or back of the ship) to get to your destination.

Your issued key card may or may not have your stateroom number on it for security reasons, but your ship’s boarding pass will. All staterooms are numbered. The first number is the deck it is located on. Depending on the size of your ship there may be one or two numbers. The next number(s) will be part of the stateroom sequencing for the deck while the very last number of your stateroom will be even or odd. Even indicates your stateroom is on the port or left side of the ship as you face forward. Odd means that your stateroom is on the starboard or right side of the ship as you face forward. Once you get to your stateroom you can unpack and relax.

When you are ready to explore your ship-observatory you should do so in daylight, as it is easier and safer.

Safety Tips

When you are walking around the ship there are a couple of safety tips you must always remember.

First and foremost you never want to have both of your hands holding something, as you want to be able to always grab a hand rail, open a door or steady yourself. Your ship at sea is always in motion and subject to sudden movements. If your hands are full and you need to grab something you have a choice to drop what you are carrying or drop yourself by possibly falling.

Second, the deck can become very slippery because of rain, snow, ice or a wash down, which is usually done in the early morning. It is very easy to slip and slide, which makes the above tip come in very handy.

Third, when going up and down ladders on the weather decks (decks exposed to the elements) they can act as a wind funnel that accelerates the wind that is present, and this literally pushes you up or down them. This is especially true in the upper decks. Be careful and hold the handrails when using the ladder ways .

Four, some ships have raised steps at passageways/doors which require you to step up and through; this also probably applies to your stateroom bathroom. If you forget to step up at these areas, you will gain a very painful reminder to do so next time.

Fifth, there can be low overheads and angled structures for you to bump your head on. Take it slow and when need be low, as you get to know your ship, and be mindful of these tips as you explore the ship.

The Main Deck

Generally there is a main deck that may or may not go completely around the ship. Some ship classes do not allow guest access to the bow, while others do. On bigger ships they usually have a helipad and lots of room. You will need to inquire with the front desk if the bow area is open at night. If it is you are in luck, because this will be the darkest place on the ship. The reason? The bridge, where the ship is controlled and manned 24 hours a day at sea, will be above and behind the bow, and there will be no lights in the bow area. It has to be completely dark at night so the watch officers can see anything in front of and to the forward sides of the ship. The bow area will also have no structural obstructions overhead, again to insure that the bridge watch officers have an unimpeded view for safe navigation of the ship both day and night.

Ship Tip

Windstar Cruises’ fleet of luxury yachts , including two tall mast sail equipped vessels, have the most open deck plan of any ship the author has sailed on to date. Their vessels allow access to the forward part of the ship, including the bridge deck, at night. The stern is also accessible at night. Their vessels are in the 10,000-ton range and are close to the water. You can really get in touch with the sea and sky standing at the very bow of their ships as they are underway. It is exhilarating and makes for great observing and astrophotography.

While you are on the bow, or if you cannot access it and are on the main deck, check out whether this deck goes all the way around the ship. Most ships, especially the mid- to larger-sized ships, will have the main deck go completely around the ship. This can be used as a walking track so it can have a number of people on it. The ship’s lifeboats may be on this deck as well or stowed above it. This deck is probably the closest deck you will have to the sea itself and will offer views on the port, starboard and stern of the ship. There will be a deck overhead, so this is not where you want to be to take astrophotographs with large sweeping views looking up. It is however the best place to take pictures of the waves and overall sea surface with the horizon in your picture.

The next place you want to check out is the highest deck on the ship. The top deck usually will be accessible via ladderways on the port and starboard sides of the ship and is where the ship’s mast, some superstructure and a lounge area is located. Some ships have shuffleboard, sunbathing lounges and a variety of recreational activities in this area. The ship may have angled glass panels or open deck railing. There is deck lighting that is usually mounted low, next to the railing, so as to not to interfere with the wide view that is almost 360 degrees. This can be a very good area to take astrophotographs, as there will be limited if any overhead obstructions, and the ship’s lighted mast with her radar devices rotating can make for some interesting compositional photographs with the background sky.

While you are on the top deck, check the next deck below it to see if it goes around most of the ship. This is sometimes known as the fitness track and often has another lounge area. This deck can afford a very good view of the sky and horizon on the starboard and port sides of the ship. You can work your way back aft or all the way forward to get sky and horizon views. Some of the ships have this deck go all the way to the stern, which gives you a higher view of the sea, the horizon and the sky than if you are on the main deck back aft at the stern.

Astrophoto Tip*

The main deck is an excellent location to take sunrise and sunset pictures that will give the closest possible view of the waves and horizon . The higher up you are on a ship, the farther the horizon is away from you; this is called height of eye. You can see this for yourself by taking a daytime picture of the horizon on the main deck and then from the top deck. I recommend doing this so you can compare the two views and use them as a reference when you are planning an observing/astrophotography session.

While you are on the main deck take photographs of the bow and stern if you have access to them to round out your field of view references. If you want a picture where the sea surface, waves and horizon are a major component in your composition this is where you want to take your picture. When stars, a planet or the Moon are close to the horizon in either a rising or setting situation this can be part of your picture as well.

Now that you have checked topside during the day it is time to do so at night. You need to do this when the ship has turned on her topside lights, which occurs at sunset. There will be multiple sources of light that come from the ship’s lighted mast, deck lights that can be high or low, bright LEDs that illuminate bars and social gathering areas and perhaps “Full Dress Ship” lights that are strung overhead from the bow to the stern. Yes, a cruise ship can be a very brightly lit place to do astronomy and astrophotography. This is why you have to do a second deck plan check at night, where you repeat your steps from the day.

The good news is that there are shadow zones or even dark zones that you can usually find. The only problem is that these zones may not line up with what you want to photograph or observe at a particular time – more on that when you learn how to plan your observing/photography session a little later in this chapter. By walking around the ship at night you can find out where there are these shadow/dark zones just by noting areas where there is less or no light present.

Another proven light avoidance or mitigation tactic is that when you are on the starboard or port side on each of the weather decks you can point your camera out towards the sea and sky by being right up against the deck railing with your tripod. You can also shield the lens of your camera from light with its lens hood if it has one, and using your hand, body or a coat to block light that might be coming in to the field of view of your camera. Taking an exposure with your camera and seeing the results will tell you if you are successful in eliminating light or not. If necessary make adjustments and take another exposure. Keep making adjustments until you have achieved the best results you can.

If you are doing visual astronomy , instead of blocking light to a camera lens, you are doing so for your eyes. Here are two nifty tricks to try. It may be as simple as holding up your arm horizontally to your eyes so that light is blocked. The second is to use a jacket or sweatshirt with a hood. You pull the hood forward on your head until the hood is past your eyes and acts like an eye shade – this REALLY works! The reason it works is because the sea and sky themselves are not light polluted – unless you are in close proximity to a large city. Even then it will be some distance away unless you are pulling into or out of port.

Sometimes late at night some areas of the ship will actually turn lights off, usually in the stern, where many ships have an outdoor restaurant that shuts down. You make your way through the restaurant towards the stern and presto – the area has no lights out by the stern. Some of your best at-sea astropics can be gotten this way.

Remember that bow or stern access if you have it and it is open at night? You have hit astronomy/astrophotography pay dirt if you have it due to no lights and a great field of view.

You have now mapped out your ship’s deck plan as to what is accessible, the view different locations afford and determined your dark and shadow zones. It is now time to learn how to integrate this knowledge with what you want to observe/photograph in the sky.

Your Stateroom’s TV Information Channel

You are on a ship at sea that must navigate her way from port to port while avoiding bad weather and other possible instances that require a course change. Most ships will provide a chart, either paper and/or electronic, that shows the projected voyage of the ship for your cruise. This chart will have a line drawn from your port of departure to each of the ports you are scheduled to visit. The ship’s voyage chart is usually located in the main reception area. If you don’t notice one, inquire as to if the ship has one. If it doesn’t you still have 24-hour access to the “ship’s navigation channel,” which is on your stateroom’s TV.

Your stateroom will have a TV channel guide, and there is almost always a “ship’s navigation” or “bridge information channel.” It usually provides a camera view of what the bridge is seeing and possibly a stern view also, which can be useful to get an idea as to actual weather topside if you do not have a window in your stateroom. Even if you have a stateroom window the bridge camera gives you a view of what is ahead. Sometimes the picture is not that great due to a dirty lens or poor quality video. The night time view isn’t very good, but usually the light of the Moon can be seen on the sea.

This channel should give you:

The ship’s current latitude and longitude, which defines her position

Sunrise and sunset times for current position

Her course and speed

A map projection as to where the ship is, showing her track (a line that indicates where the ship has traveled and is headed)

The ship’s current date and time (maybe even time expressed as Coordinated Universal Time or Universal Time Coordinated (UTC)

Current weather, which includes:

Sea state

Wind speed – true speed and direction, relative speed and direction

Cloud cover

Precipitation

Humidity

UV index

Day’s temperature high and low with several days’ forecast

Nautical miles traveled since last port and overall distance covered with distance to next port with estimated date and time of arrival

We’ll now discuss how these pieces of information are vital to planning your observing and astrophotography sessions onboard ship.

To correctly use the astronomical software, star charts or planisphere you brought along you need to know how to use them. Make sure you have the instruction manual for your particular system that you are going to use. Hopefully you have become familiar ashore with the operation of the system you will use at sea in order to maximize your precious time at sea. If not use the daytime hours to get familiar with your particular system, as you do not want to be wasting time under the stars figuring everything out.

To use any system you have to know your location. In Chap. 4, “Location, Location, Location,” you’ll learn about how where you are literally in the world will affect what you see in the sky. But first we need to put the ship’s position information to work.

Depending on your ship’s IT capabilities and what you sign up for – it all comes with a cost (unless you have a special offer as part of your booking such as reduced price for or free Internet) – you may be able to use the “Current Location” feature on your software. This feature uses Global Positioning Satellites (GPS) to update your location. Quite frankly this has never worked for this author at sea on my smartphone or computer . Even with Wi-Fi enabled and connected to the Internet I get an error message when I try. It may work for you. Also note that most ships provide their Internet on a “one device only” basis, so you have to manage which device you are using when you try this feature if you have your software on all of your devices. If you can’t get a location update automatically you’ll just have to do it the old-fashioned way, by entering your longitude and latitude manually. Make sure you input the proper hemisphere – E/W or N/S when doing so.

This should be a simple process of accessing the ship’s information channel and inputting the ship’s position into your software in the “Latitude and Longitude” input boxes. You do not have to input beyond degrees and minutes of latitude and longitude (which may be all the ship’s information channel provides), as your requirements for accuracy at sea are not that stringent. You are not operating a telescope or looking for split second timing of an astronomical event. Even satellite timings will be accurate enough for naked-eye observation.

The real issue becomes time and what time zone you are in. When you input ‘location” into your astronomical software, besides using “Current Location,” “Latitude-Longitude,” you can also pick a country and then a city chosen from a list that is part of the software or maybe you will click on a map. The cities and the map should automatically input the time zone for you. But when you input the latitude and longitude manually you will probably have to input the time zone. Some ship information channels will have the UTC available, some will not.

If your ship does not provide UTC you will have to determine it yourself by looking up on the Internet a conversion website and input ship’s time to UTC, which will result in a “–” or “+” or 0 value. It is really important to input the right value, as if the wrong time is inputted even though you have the right location it will result in an error-filled sky on your software. If you do not have Internet you can ask at the Reception desk if they can find out for you what the UTC is. In the ship’s library there may be a world atlas that gives you the time zones of the world so you can try to work it out by knowing the ship’s location and seeing where the resulting time zone is.

One other complication is that the ship may play fast and loose with time zones. One ship changes time zones at 2 p.m. instead of 2 a.m. for guest convenience, and there are times when time zones get a bit stretched. This can make it difficult to exactly know what time zone you are really operating in. The only times when this becomes crucial is when you are preparing for solar and lunar eclipse events and satellite viewing opportunities. These events need an accurate time in order to be viewed at the proper time. Being off on your time zone will make you off in these events, so much so that you may miss portions of the eclipse or the viewing of a satellite. Again, if you want to confirm your true time zone for accuracy try the reception desk for help.

Planispheres are a bit easier to use as they generally have clear star field overlays that go by latitude N or S in some value of degrees, e.g., 20 degrees N, 40 degrees N, etc. Inputting the date and time gives you an approximation of the sky. Planispheres are very limited in the number of stars they present, mainly just the major constellation outlines with some stars identified and no information on planets. You have to know what constellation these are in, which means another source of information you need to refer to. They also are small by necessity, which can make them hard to read at night under red light. They do not provide any data on the stars. They are not a good choice for taking to sea.

Star chart books can be bought that detail the sky usually by the month and for a certain latitude range. Information about the stars, constellations, planets and eclipses are usually included. They are somewhat useful but are more bulk to carry and may not be the best thing to use when you are at sea, especially if you are going through multiple hemispheres.

Once you have checked out the ship to see where the observing/astrophotography shadow/dark zones are, and inputted your position and time into your software or your planisphere or star charts, you will have a view of what is in the sky overhead for your ship-observatory. You need a few more pieces of information from the ship’s information channel, though, before you head out to observe or photograph the sky.

Sunrise and sunset times are on the ship’s information channel and are listed in the ship’s daily bulletin, which contains the day’s events aboard ship. This information is necessary for observing morning and evening phenomena such as sunrises, sunsets, Earth’s shadow, zodiacal light, Mercury and Venus; all of these are covered in later chapters.

Knowing the Weather

You will need to know the weather. What is the sea state? The wind? Cloud and precipitation forecasts? The sea state will tell you how high the waves are and possibly the distance between the waves, which affects the motion of the ship. Generally the higher the waves and the larger the swells (waves that travel large distances after forming) the more the ship will move up and down and roll from side to side. This won’t affect your unaided visual observation of the sky but could negate the use of binoculars if the motion is too pronounced. It can have a HUGE effect on photographing the night sky, as invariably you will need to take a time exposure which will capture the ship’s motion and make the stars and planets look like an electrocardiogram (EKG) or modern art piece. Tips on how to assess and minimize this motion are covered in Chap. 16.

If the weather is too extreme the captain will order that the weather decks be closed, resulting in the access points to the main deck or some of the top decks being closed. DO NOT ignore these and go topside when such barriers are in place. You can place yourself in real danger. This situation can arise from either rain, thunderstorms, ice, wind , sea state or a combination thereof. If you break the safety protocols and are caught it might not be a pleasant situation to be in.

Another very important weather factor is the wind, which is measured in knots, meters per second and/or miles per hour. The higher the wind speed the more you have to be careful and mindful of places on the ship where you might need to block the wind. The wind is affected by the ship’s course and speed. True wind is the true direction of the wind in degrees of azimuth with its inherent true speed, while relative wind adds the effect of the ship’s course and speed.

When you go up on deck, look at the top of the ship’s mast. There will be a “wind vane” (the ship’s anemometer) that shows the direction of the wind and a “propeller” that measures wind speed. This is a visual clue for you to use in planning your observing or astrophotography session. Even at night the ship’s anemometer should be visible, as cruise ship masts are illuminated unless the ship is in “pirate condition” (this is real along the coast of Somalia and surrounding areas), which may necessitate a darkened or altered light profile of the ship.

Your Ship’s Course

Your final factor in planning your astronomy/astrophotography session is the ship’s course. She will be headed on a course that will be measured in degrees, 0 to 359, with 0 degrees being North, 090 degrees East, 180 degrees South, and 270 degrees West. These are the four cardinal directions and also coincide with the same cardinal directions in your software, planisphere or star charts.

Astro Tip

You should have N, E, S, and W highlighted on your software settings so they appear on the virtual horizon that is in your sky view. Your settings will also allow you to mark the point directly overhead in the sky at 90 degrees above the horizon known as the zenith. You should also turn on the meridian setting, which will have a line from N to S highlighted in your sky view. This helps in orienting you as to N and S. When astronomical objects transit the meridian they have reached their highest point in the sky for the day or night.

Your software should have the ability to click on the object you want to observe to highlight it and then click on a tab marked “Data/Description.” The data section will give you all kinds of physical data on your object of interest to include its azimuth (0 to 359 degrees) and altitude (0 to 90 degrees) above the horizon. If you have inputted the date and time you want to observe this object you will have its position to look for it in real time. The description will give you useful background information on the object as to its history, folklore and contributions to astronomy. There might even be a picture of it.

If you are looking to view the constellations it is a big help to have their outlines active on your settings menu, as this will help orient you. To get the position of a constellation (some are quite large in the sky) in altitude and azimuth just click on a star located within the boundary of the constellation, preferably a bright one (your software will show stars of varying levels of brightness and different colors so the constellation will be an accurate representation of what you will see in the sky). Use this information, along with the bright star, to go topside to find the constellation.

Another huge benefit for your sky sessions using your software (if it is loaded onto your smartphone or tablet) is the “Gyroscope” or “Compass” feature. This allows the real time sky view in your smartphone/tablet to “follow” your movements as you move your smartphone/tablet. If there is an object you want to find you can use the sky view in your smartphone/tablet to locate it, select the COMPASS or GYROSCOPE view, and then move the smartphone/tablet to align with your object. Note, you should have your software in “NIGHT VISION” mode, which shows the view in red light to preserve your night vision.

The ship will probably remain on one course for the duration of your session, even if you are up all night. Only when the ship is in proximity to entering or leaving port or having to maneuver to avoid ship traffic or weather will she change course. Otherwise she transits on a steady course that changes over days – especially in ocean crossings. The ship’s course will determine where on the ship you will have to go to see your astronomical object of interest.

This is where your previous exploration of your ship’s deck plan comes into play. You know the layout of the ship, so once you know the ship’s course the bow , stern, port and starboard sides will all be aligned with a certain section of the sky. You will need to align the direction of the object(s) you want to view/photograph with the location of the ship, which gives you access to that section of the sky. You will have multiple options for viewing/photographing the sky, and this is where your determination of dark and shadow zones proves its worth. Odds are that one of your options will have less light than the others; failing that, remember to bring your hooded jacket to block out light.

If what you want to see is located in the eastern part of the sky and the ship is heading in an easterly direction you could use these options:

Go to the bow

On the highest accessible deck move to the forward part of the port or starboard side, and look forward.

Each of these locations would give you a wide view of the sky.

If your object is in the southern part of the sky and the ship is heading in an easterly direction:

Go to the bow and face to starboard (south)

On the highest accessible deck face the starboard side (south)

On the main deck, starboard side, face directly south.

Go to the stern and face to starboard (south).

If what you want to see is located in the western part of the sky and the ship is heading in an easterly direction you could use these options:

On the highest accessible deck move to the aft part of the port or starboard side, and look aft.

Go to the stern.

Each of these locations would give you a wide view of the sky.

If your object is in the northern part of the sky and the ship is heading in an easterly direction:

Go to the bow and face to port (north).

On the highest accessible deck face the port side (north).

On the main deck, port side, face directly north.

Go to the stern and face to port (north).

Now that you have seen some examples here are the recommended steps to go through to align your astronomical object with the course of the ship for your upcoming session.

1.

Use your software, planisphere or star chart to select what you want to observe/photograph.

2.

Note the azimuth and altitude of your object. Some software will allow you to make an observing list for a session, which is very convenient.

3.

Turn on the ship’s information channel and note the ship’s course. It is very helpful to see the ship’s course depicted on the map projection view, because the orientation of the ship’s direction shows it relative to the cardinal directions on the map view. N is top, S is bottom, E is right and W is left. This visual orientation helps in aligning to the sky.

4.

For the first few times you do this get a piece of paper and label the cardinal directions on it. Next draw the figure of a ship (large enough so you can read it) in the same orientation of the ship’s course shown on the TV and label the bow, stern, port and starboard. Now you have a reference you can use to help orient you as to where to go on the ship to see your object.

After you have plotted out a few observing sessions you will be able to look at the ship’s position on the TV and align it with your planned observing/astrophotography session. If not, no big deal, as you can just continue to plot it out. In our next chapter we will build upon this skill you have developed, as your cruise(s) may take you to the other hemispheres of the planet, introducing new opportunities for observing and astrophotography.

© Springer Nature Switzerland AG 2018

Gregory I. RedfernCruise Ship Astronomy and AstrophotographyThe Patrick Moore Practical Astronomy Serieshttps://doi.org/10.1007/978-3-030-00958-8_4

4. Location, Location, Location

Gregory I. Redfern1  

(1)

NASA JPL Solar System Ambassador, Ruckersville, VA, USA

Gregory I. Redfern

Unlike observing from a fixed position on land, when underway your ship-observatory is constantly moving. The latitude, longitude and time zone need to be constantly updated in your software, planisphere or star charts, as we learned in the last chapter. Your cruise may stay in a single geographical area, like the Caribbean, or go from port to port in one country or several close by countries, again a relatively compact area. But if you are on a transoceanic cruise that is crossing the Atlantic or Pacific, or one of the “Grand Voyages” that can last 30 days or longer, you will be potentially changing hemispheres and undergoing large shifts in latitude and longitude. This can radically alter the view of the sky.

We live on a planet that is spherically shaped. It has a North and South Pole, each at 90 degrees latitude respectively. On a map or chart the horizontal lines of latitude go from 90 degrees to 0 degrees – the equator – the dividing line for being in either the northern or southern hemisphere of the planet. For east and west directions and hemispheres on our planet, the lines of longitude run vertically through the poles and are measured from 0 to 180 degrees east and west. By historical convention the 0 degree line of longitude was established at Greenwich, England, at the Royal Observatory in 1884 and was known as the Prime Meridian. It was from this line that all positions on Earth were measured east or west (Fig. 4.1).

Fig. 4.1

Greenwich Prime Meridian. (Image by the author)

It was also from this zero longitude reference line that thousands of astronomical observations were made using the Airy Transit Circle , whose crosshairs marked the actual Prime Meridian (Fig. 4.2).

Fig. 4.2

Greenwich Airy Transit Circle . (Image by the author)

Astronomers were able to make an accurate map of the visible sky using these observations. The Prime Meridian was updated between 1984 and 1988, with the nations of the world deciding in 1984 to adopt a new 0 degree longitude line called the International Reference Meridian, or IRM. The IRM is located 102.5 m to the east of the historical Prime Meridian. It became necessary to update the location of the Prime Meridian so that it was actually measured from the center of Earth rather than its surface to provide the greatest precision for position and time measurements. The Prime Meridian also became the basis for the world’s 24 time zones, which are based on increments of 15 degrees of longitude. Prior to the establishment of these international conventions of longitude and time zones there were no universally accepted standards.

We discussed adjusting your software’s time zones in the last chapter to make sure you had the correct time to plan your observing-photography sessions. We also touched on the ways to get the ship’s longitude and latitude for input to your software, planisphere or star charts. If you are on a long voyage that is covering thousands of miles this is really important, as you may cross from one of the four hemispheres – north, south, east, and west – into another. When that happens the sky can take on a whole new appearance.

Another factor affecting your view of the sky on a longer voyage, and on shorter duration cruises, is the time of the year. Our planet goes through four seasons each year – winter, spring, summer and fall – that are caused by the 23.5 degree tilt of our planet’s axis and our orbit around the Sun. If Earth had zero axial tilt we would have no seasons, and every day would be exactly like the one before and after – 12 hours of daylight and 12 hours of darkness. We experience this on two days of the year, the vernal equinox, which occurs on or near March 21 and marks the start of spring in the Northern Hemisphere with fall for the Southern Hemisphere, and the autumnal equinox, which occurs on or around September 21 and marks the start of fall for the Northern Hemisphere with spring for the Southern Hemisphere. Equinox means “equal night” in Latin and signifies the equal hours of day and night. (They are almost equal, as there are some slight variations due to atmospheric refraction.)

Winter starts on the winter solstice, on or around December 21 in the Northern Hemisphere, with summer solstice for the Southern Hemisphere. Summer starts on the summer solstice on or around June 21 in the Northern Hemisphere, with winter solstice for the Southern Hemisphere. The winter solstice marks the shortest day of the year, as the Sun is at its lowest point in the sky for the year. The summer solstice is the opposite, as the Sun is at its highest point in the sky for the year and is the longest day of the year.

If you have a clear view of the eastern horizon at your home you can watch the progression of the Sun along the horizon each day of the year. This applies to both the Northern and Southern Hemispheres. You only have to use the appropriate seasonal date for your hemisphere. The Sun will shift its position along the horizon with each sunrise. It will move along the horizon towards the north until it reaches its farthest point on the summer solstice. The Sun will then start to move along the horizon towards the south, reaching due east at sunrise on the autumnal equinox. The Sun then moves farther south along the horizon until it reaches its lowest point on the winter solstice. After that the Sun starts to move north again along the horizon, once again reaching due east at sunrise on the vernal equinox. The same progression is visible at sunset except due west is marked on the equinoxes. Maybe you will have landmarks that you can use to know when the Sun reaches each of these points. It can become a habit to watch the Sun’s journey not only along the horizon but in the sky as well.

You can see this easily in your software. From a wide horizon view put the Sun in the east and input a time such as 6:00 a.m. Have the meridian due south and select the “Date/Hour” for “days.” Input one of the seasonal dates and note where the Sun is on the horizon. You may have to adjust the view to coincide with sunrise for that date, but if you run it with continuous days you will see the Sun move along the horizon at sunrise.

This pattern of the Sun along the horizon is difficult to observe at sea due to the ship’s changing course and perhaps landforms that block the view. But if you are on a long voyage you can see the Sun changing its altitude in the sky at around noon. Based upon their position navigators can calculate local apparent noon, which is when the Sun is at its highest altitude in the sky at the instant of local noon. This would be measured with a sextant for the Sun’s altitude and a timepiece for time and after appropriate calculations can give you your longitude and latitude, which can be used to update your position.

Once again you can see this easily in your software. From a wide horizon view put the Sun in the south (north for Southern Hemisphere) and input the time for 12:00 p.m. Have the meridian due south (north for Southern Hemisphere) and select the “Date/Hour” for days. Input one of the seasonal dates and note where the Sun is in the sky. You may have to adjust the view to keep the Sun visible as it coincides with the highest point in the sky as the day progresses. Run it with continuous days, and you will see the Sun change its altitude in the sky.

Now, where the seasons become important, other than the expected weather you will encounter, is what stars and constellations will be visible. Each season has constellations and stars that are visible when the season starts and ends; it is a process that takes months. In fact, the stars in the sky can tell you what season it is just by looking at what constellations are visible. As you get better in knowing the sky you will get to the point of knowing what month it is just based on the constellations you see. This is where having monthly star charts can be valuable. You can also see the sky by month on your software, but it is generally easier to look at a star chart for each month, as it is a bit more of a straightforward view.

Earth orbits the Sun once every 365.25 days, which defines our year. As a result of this Earth moves a little less than a degree a day on average, which causes the stars to rise in the east a little earlier each night, approximately four minutes in case you were wondering. You can see this happen in your software; below we will use a star prominent in the Northern Hemisphere sky to illustrate. If you live in the Southern Hemisphere you can chose a star and run the same simulation.

Using your home location input the date March 23 with the current year. Make the time 8:00 p.m. using your own time zone. Let’s use Arcturus, known as the “star of spring.” Select it. Have your horizon view as wide as you can make it so that you can see Arcturus in the east (left) with the meridian – south – in the center of the sky view.

Then go to the “date and time” feature, choose “Day” and click on the arrow that moves the sky either a day at a time or continuously. Watch the date change while looking at the star’s motion from night to night. You will see it move across the sky from east to west and eventually disappear from view as it moves into the Sun’s glare.

You can see multiple seasons and their stars and constellations in the sky during the course of the night. Let’s say it is April 18, and we are in the Northern Hemisphere. As it gets dark after sunset the constellations of winter come into view, some low in the west while others are high overhead. Orion, Taurus and Canis Major are low in the west while Gemini, Canis Minor and Auriga are a bit higher in the sky. If you look to the east you will see Leo, Virgo and Bootes with more spring constellations. At around 2 a.m. you will see the summer constellations making their appearance, including the Milky Way in the southeast and east.

By going through these examples it should be pretty clear that what time of year you go on a cruise impacts what you will be able to see in the sky. If there is a particular object that you want to see the best thing to do is to use your software or your planisphere or star charts to determine the best time of year/season to see it, and narrow down your cruise choices accordingly. But that is not all you have to take into consideration.

You have to take into account that we live on a spherical planet. Astronomers refer to this as the celestial sphere, which depicts the sky as seen from Earth’s center. Because of this we see the night sky differently from each location on Earth. The celestial sphere aligns with Earth’s North and South Poles and the equator, i.e., giving us the north celestial pole (NCP), south celestial pole (SCP) and the celestial equator. The NCP is at 90 degrees declination (more on this in a moment) north (N), or “+”, the celestial equator at 0 degrees declination and the SCP is at 90 degrees south (S) or “–” declination. The star Polaris is less than a degree from the NCP, and the star Sigma Octans is used to mark the SCP.

Your position on Earth determines what you can see in the sky. If you were at the North or South Pole, you would see the stars during the night moving from east to west in the sky, but they would never rise or set. You would see stars that are from either + or – 90 degrees declination to 0 degrees declination, the celestial equator.

At the equator, you theoretically could see Polaris and Sigma Octans, the NCP and SCP, but in reality they would be difficult to spot right on the northern and southern horizons. At the equator the entire sky, North to South would be visible. Although you may end up cruising at the poles and directly along the equator, chances are that you will be somewhere else on the planet and need to figure out what will be visible in the night sky.

At sea away from land we can see 360 degrees in azimuth (the entire sea horizon ) and 0 to 90 degrees in altitude (sea horizon to directly overhead). But when we look at the stars in the night sky we can only observe a segment of the sky that is dependent on your latitude. We already discussed the appearance of the sky at the poles and the equator. But how much of the sky can we see from other locations?

For the Northern Hemisphere, Polaris, the North Star, essentially shows you your latitude, as it is so close to the NCP. But if you know your latitude you can determine how far south you can see stars. There are two ways to do this. First, you can input your position in latitude and longitude into your software. Next, make sure you have the meridian feature turned on and aligned so that you are looking directly south in your horizon view. Now zoom in so that you can see stars directly on the meridian line. If there are none advance your view by using ‘minutes’ on your date/time feature until there are. When you notice a star that is on the meridian and very close to or actually on the horizon, select it and then select “info.”

Your software will have an information section on the star. You will see the altitude – its height in degrees above the horizon – and azimuth – its location in degrees along the horizon. This will tell you where it is in your sky. There will also be the star’s “Celestial Coordinates” in right ascension – the equivalent of longitude on Earth – and declination – the equivalent of latitude on Earth – to show the position of the star on the celestial sphere. Right ascension measures the star’s eastward distance from the prime meridian of the celestial sphere in hours, minutes and seconds. A star’s declination is how far above or below the celestial sphere’s equator a star is and is measured in “+” or “–” degrees, minutes and seconds. The “+” is above the celestial equator, while “–” is below it.

The other method is to simply take your latitude and subtract it from 90 degrees. If you are in the Northern Hemisphere put “–” in front of the answer, which shows how far south you can see on the celestial sphere. If you are in the Southern Hemisphere put a “+” in front of the answer, which shows how far north you can see on the celestial sphere.

Imagine that you want to see the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) – we’ll discuss these in Chap. 7. First you would need to look up what time of year would they be visible, and then how far south you would have to be to see them. It can take a while to get a cruise that goes far enough south to see them respectively at approximately −69 and –72 degrees declination. Theoretically you might be able to glimpse the LMC right on the southern horizon at 21 degrees N latitude, but realistically speaking you would need to go below the equator a good distance to see them in all their glory.

So how do you go about picking a cruise that will get you a view of an astronomical object you want to see? There are two ways you can approach this. In the first method you pick a cruise that you like, very similar in the manner we discussed already in Chap. 1. You search the Internet for shore destinations and/or transoceanic voyages that interest you. Once you have a cruise or two that meet your liking you look at the itinerary. What are the dates, and where does the ship go?

You combine the information from the dates, which you can translate into seasons, with the ports of call or the bodies of water that the cruise will visit. With the dates and expected locations you can check your software, planisphere or star charts to see what the sky looks like during the dates of the cruise. You can research the constellations, stars and view of the Milky Way, other galaxies and deep sky objects that are visible. Remember, if you are on a long voyage that lasts months the sky will change over time, so be sure to take that into consideration.

Next you take the ports of call or the bodies of water your ship will be sailing to and through to determine the approximate positions in latitude and longitude that are involved. You can get this by looking up the ports of call on the Internet. If you are transiting an ocean you will be crossing multiple time zones (longitude) and perhaps a wide range of latitudes. You can determine from the itinerary and the positions of where you embark to get an idea of the route you are taking. You do not have to be precise in your estimate of what the ship’s positions at sea will be. You just want to know what the estimated latitude and longitude of the ship will bring into view on the celestial sphere during the duration of your voyage. As you have learned you have a fairly large view of the sky from any position on Earth. You are just trying to see what the season will be to know what will be visible in the sky and if you will be in a location to see something in particular that interests you.

The other method of picking a cruise is similar, but in this case you know what you want to see in the sky and you have to match up a cruise selection to it. If there is a specific object in the sky, a celestial event such as a solar or lunar eclipse (Chap. 10), meteor shower (Chap. 12), etc., your first step is learning all that you can about it. This is when having access to reference material, as we discussed in Chap. 1, will help you in learning about the sky and what is happening in it. You can obtain useful information and observing tips that will help you in your quest to see your item of interest. When will this celestial object or event be visible and at its best for viewing?

Once you know the particulars as to the timing for your object or event you can then determine the best viewing location. Do you need to be in a particular area of coverage, as happens in an eclipse? Or are you more concerned with the latitude range to make sure you can see what you are looking for? You need to determine the general geographic position you need to be in – what hemisphere, what latitude range – so that you can match that up to ports or transoceanic voyages.

Once you know the timing and general positioning required for your object or event you can do an online search. If you have a cruise line of choice you can start at its website using its cruise search function that you learned about. You can input a time frame and general location and check the results. If there is a match, check out the voyage itinerary to determine where the ship is going and the actual time frames involved. If you do not have a specific cruise line in mind then you can use the cruise search techniques from Chap. 1 to try and narrow down your selection choices.

It is highly recommended that you consider a cruise that takes you below the equator, as it is really something to watch the sky transform. You can make the equator crossing from north to south or vice versa. It is most dramatic, some cruisers say, if you sail from the hemisphere where you have resided for the majority of your life to the one where you are a newcomer.

If you start from the Northern Hemisphere and head south the most obvious thing to look for in the sky is Polaris, the North Star, starting to get lower and lower in the northern sky. It becomes apparent that your northern latitude is decreasing and the stars south of you that you may not have seen before are becoming visible. Depending on the time of year and the ship’s course you might be able to see Polaris and the Southern Cross at the same time (Fig. 4.3).

Fig. 4.3

Object Viewed: The Southern Cross. (Image by the author)

Ship: Azamara Quest

Lens used: 28–300 mm at 28 mm f/4

ISO: 10,000

Exposure: 3 seconds

Comment: The Southern Cross is visible almost vertical in the center of the shot above the glass. Alpha and Beta Centauri are to the left. High ISO to bring the stars out

The Southern Cross is a famous asterism that mariners have used throughout the millennia to mark due south when the Southern Cross stands upright. When it rises in the southeast it is horizontal, and it becomes more and more vertical as the night progresses due to Earth’s rotation. There is a false cross that precedes the real one, but you can always pick out the Southern Cross by the presence of Alpha and Beta Centauri, two bright stars that are to the immediate left of the Southern Cross (Fig. 4.4).

Fig. 4.4

Objects viewed: The false cross vs. the real Southern Cross. (Image by the author)

Ship: Azamara Journey

Lens used: 35 mm f1.4

ISO: 160

Exposure: 5 seconds

Comment: This exposure was taken with low ISO and long exposure to capture just the stars to show the two crosses. A higher ISO would have captured background stars and the Milky Way

Another amazing sight in crossing the equator to the southern hemisphere is how some constellations begin to appear the farther south you go. They literally can appear upside down! The most conspicuous constellation to undergo this transformation is the famous and easy to spot winter constellation Orion the Hunter. In the Northern Hemisphere Orion’s left shoulder is the bright orange star Betelgeuse, while his right foot is the bright white star Rigel. The famous three stars in a row of his belt hold his sword, which is to the lower left of the belt and contains the Orion Nebula – a massive star-forming region in our galaxy that is visible to the unaided eye (Fig. 4.5).

Fig. 4.5

Object viewed: Orion. (Image by the author)

Ship: Nautica

Lens used: 14 mm f2.8

ISO: 3200

Exposure: 10 seconds

Comment: Fishing boat lights blaze away with Orion in the Malaca Straits

The farther south you go in the Southern Hemisphere the farther to the northern horizon Orion moves. We in the north are so used to seeing Orion in the south it is quite the view to see the mighty hunter lingering in the northern part of the sky! (Fig. 4.6).

Fig. 4.6

Object viewed: Orion Down Under. (Image by the author)

Ship: Azamara Journey

Lens used: 35 mm f1.4

ISO : 3,200

Exposure: 0.6 seconds

Comment: Orion is literally upside down deep in the Southern Hemisphere

The Moon is another object that really catches your eye as you transit farther south. The Moon has a wide range of movement in the sky as it follows the ecliptic, which is the imaginary line through the celestial sphere that the Sun, Moon and planets can be found. The ecliptic lies within the 12 constellations of the Zodiac – Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpius, Sagittarius, Capricorn, Aquarius and Pisces. A portion of the ecliptic also runs through the summer constellation Ophiuchus, but this is not part of the zodiac.

The other thing you will notice about the Moon in the Southern Hemisphere is that when it is preparing to set in the northwest it will appear to be upside down as compared to the northern view.

It can be quite surprising when you first see the Moon so close to the northern horizon at about 35 degrees south latitude. But you will also notice that the face of the Moon looks completely different as well. When you think about it these observations make sense after you remember that you are on a spherical planet and you have gone “down under” (Fig. 4.7).

Fig. 4.7

Object viewed: Moon. (Image by the author)

Ship: Azamara Journey

Lens used: 300 mm f/5.6

ISO : 200

Exposure: 1/640 second

Comment: This picture shows how the Moon appears “upside down” deep in the Southern Hemisphere, in Fremantle

Being at and below the equator also moves the ecliptic farther up in the sky so that the planets at times are moving almost directly overhead, depending on how far south you go. The Milky Way is farther up in the sky as well, which can afford stunning views with an optical aid such as the Vixen 2.1 × 42 binoculars. If you have never been “down under” on a cruise you may want to consider taking one that goes to Australia. The Australian sky is exceptional, especially in the April to July time frame.

If you input Sydney, Australia, into your software as a location and use April to July in a month by month view, you will see the Milky Way change its orientation in the sky and be almost directly overhead with the Southern Cross, LMC and SMC visible. The best months from Sydney to view the LMC and SMC in the evening hours, as you can see in your software, is January to March. They are right on or near the meridian, which means they are at their highest.

Australia is a very big continent, and there is much to see. Many of the cruise lines offer voyages that can take in several ports or go around the whole continent. The air travel time from the United States to and from Australia is long, though. Some passengers book back to back cruises to see more of the continent and to avoid jet lag. It is not a bad way to go if you have the time and funds. Another thing passengers do is to spend time ashore prior to or after the cruise exploring. Some cruise lines will have shore excursions or hotel accommodations before and after the cruise for those guests who want to extend their stay and explore on their own. It is a good way to enhance your cruise experience.

If you are heading north above the equator for the first time you are in for some sky watching treats. The first is Polaris; you can watch the North Star rise higher and higher as your latitude increases. At or near the equator Polaris is fairly bright and steady on the northern horizon (Fig. 4.8).

Fig. 4.8

Object viewed: Polaris (North Star) Viewed At the Equator. (Image by the author)

Ship: Nautica

Lens used: 14 mm f/2.8

ISO: 5000

Exposure: 5 seconds

Comment: This picture shows Polaris, the North Star, right on the horizon at the equator. Ursa Major, the Big Dipper, is upside down directly above

Accompanying Polaris is Ursa Minor, the Little Bear, also known famously as the Little Dipper. Polaris is the tail of this constellation. A favorite of northern sky watchers is Ursa Major, the Big Bear – also known as the Big Dipper. The Big Dipper is a large and easy to see constellation that rotates around the Little Dipper and Polaris. They form an easy to see and recognizable duo that will be a fond memory for first-time observers. The outermost stars of the bowl of the Big Dipper, Dubhe and Merak, are known as the “pointer stars to Polaris” as they always point to the North Star.

The time of year will dictate what you can see, but another favorite for the Northern Hemisphere summer is the Summer Triangle, a large asterism formed by the stars of Vega, Deneb and Altair, which is visible at 15 degrees south latitude but really comes into its own when you get above the equator and higher. The Milky Way runs right through the Triangle, with the magnificent “Great Rift” – also known as the “Dark Rift” – visible along with the Scutum star clouds. This northern part of the Milky Way merges with the Milky Way in Sagittarius and Scorpius, which Southern Hemisphere observers would be more familiar with.

Not to be missed in the Northern Hemisphere fall is the Great Square of Pegasus with the attached constellation of Andromeda. Located within Andromeda is the Andromeda Galaxy, M-31; you will want to see this and photograph it. We’ll have more on this spectacular galaxy in Chap. 7. Nearby the Andromeda Galaxy is the Triangulum Galaxy, which is also discussed in Chap. 7.

If you are going to be on one of the long or grand voyages it is highly recommended that you make up an observing list of what you would like to see in the sky based upon where your ship is going to be. Start with the beginning of your trip while taking into account the season and the ship’s location. Then add to it as your season and/or latitude changes. This will make it easier to enjoy your voyage and modify your list as the cruise goes on and changes latitudes.

Making an observing list before you leave on each cruise is actually a good thing to do, as it focuses your attention on what you want to see and prepares you in advance. It will also give you something to work with while you are on cruise, and save time and Internet minutes. Your software may have an “Observing List” option, so you could make up multiple lists. It might be easier, however, to just take a copy of the ship’s itinerary and write down what you would like to see in each season or ship’s location. We’ll have more on this pre-cruise preparation in Chap. 16.

Now we begin our discussion and exploration of the sights to see or photograph while you are at sea.

© Springer Nature Switzerland AG 2018

Gregory I. RedfernCruise Ship Astronomy and AstrophotographyThe Patrick Moore Practical Astronomy Serieshttps://doi.org/10.1007/978-3-030-00958-8_5

5. The Sun, Sunsets, Sunrises and More

Gregory I. Redfern1  

(1)

NASA JPL Solar System Ambassador, Ruckersville, VA, USA

Gregory I. Redfern

This chapter is all about the Sun, but let’s get the most important thing out of the way first – safety!

Solar Viewing and Solar Photography Safety

FAILURE TO FOLLOW THE SAFETY PROCEDURES INCLUDED HERE WILL CAUSE PERMANENT EYE DAMAGE AS WELL AS RUIN YOUR CAMERA.

1.

NEVER look at the Sun (except during totality of a total solar eclipse ) unless you have approved and certified solar viewing glasses with certification ISO 12312-2. These are also informally known as solar eclipse glasses.

2.

NEVER photograph or look at the Sun unless you have an approved and certified solar filter that properly fits for the front of the lens you are using. You also need to have an approved and certified solar filter for the sunward side of each optical aid you bring along to observe/photograph the Sun.

3.

NEVER photograph or look at the Sun through a viewfinder unless you have an approved and certified solar filter over the viewfinder, if your camera lacks through-the-lens viewing. The viewfinders of digital single-lens reflex cameras (DSLRs) are made safe by the use of an approved and certified solar filter in front of the lens.

4.

Even when using your approved and certified solar filter(s) and solar viewing glasses DO NOT STARE for long periods at the Sun as an extra precaution. Look through them briefly (seconds) and then look away. By doing so any tiny hole or imperfection that is present is not likely to cause you any harm.

5.

As an extra precaution, DO NOT STARE at the Sun for long periods through your camera’s viewfinder, even with an approved and certified  solar filter on the camera’s lens, again in case of holes or other imperfections in the solar filter. Look through it briefly (a few seconds) and then look away. If available use your camera’s LIVE VIEW function.

A list of reputable vendors for purchasing approved and certified ISO 12312-2 solar eclipse glasses (used for your eyes only) and approved and certified solar filters for your lens(es) and any optical aid you use have been included in the book’s Appendix. See also https://​eclipse.​aas.​org/​eye-safety from the American Astronomical Society. Follow the guidelines and manufacturer’s instructions for the solar eclipse glasses and solar filter’s use and how to check them before each use. Read and print out the information contained in the SOLAR VIEWING AND PHOTOGRAPHING SAFETY listings in the Appendix for this chapter to take with you to sea in case you cannot access the Internet. If some of the the link(s) do not work when you try to access them refer to https://​eclipse.​gsfc.​nasa.​gov/​SEhelp/​safety.​html and https://​aas.​org/​eye-safety.

6.

Do not attempt to view or photograph the Sun total solar eclipse, unless you completely understand the procedures required to safely do so. If you do not understand them, contact an appropriate organization for clarification.

7.

There is little information available on how to safely photograph the Sun using tablets. Accordingly you will find no information in this chapter on how to do so. Since you wouldn’t be looking through them, there is no way you could hurt your eyes, but the tablet’s lens focusing on the Sun could damage the tablet’s camera.

This chapter is intended as an introduction only, as whole books have been written on viewing and photographing the Sun. Some are listed in the Appendix of this book.

With the above being said you can easily purchase online from reputable dealers (see the Appendix for this chapter) ISO 12312-2 certified and approved solar viewing glasses and approved and certified solar filters for each of your camera lens(es) that you would use during the partial phases (or indeed, outside of the solar eclipse entirely) and any optical aid you bring along to view or photograph the Sun. This will safely allow you to observe and photograph the Sun if you so desire.

If you are going to observe and/or photograph a solar eclipse, see Chap. 10. Chapter 10 will also discuss some of the structures of the Sun that are visible in a solar eclipse.

To see the Sun in all its glory a properly equipped telescope or binoculars with approved and certified solar filters is needed. However, there really isn’t much you can observe on the Sun at sea, as it is mostly featureless unless a large sunspot group appears (and we are at the minimum of the sunspot cycle with the Sun being blank on most days through at least 2020) or there is a solar transit of Mercury (though the tiny silhouette of Mercury will be almost impossible to view from a rocking ship) or Venus (whose next transits will be in 2117 and 2125, over a hundred years in the future). The only transit coming up soon will be of Mercury on November 11, 2019.

The above information applies to safely observing or photographing that transit of Mercury, but it will be an event more interesting intellectually than physically. There will be additional information available in the astronomical comunity months before the transit so make sure you stay informed. However, the Sun sets the stage for other events that you will want to see, as we’ll discuss later.

Our Star, the Sun

As you will learn in Chap. 8 it took some time for the Sun to form at the center of the Solar System. In 1900 we did not know how the stars worked. There was some speculation that they shined because of the constant infall of meteors. Or maybe gravitational attraction was at work, or perhaps it was some process related to the newly discovered radioactivity. It wasn’t until Einstein determined his famous equation E = mc² in 1905 and the mass of four hydrogen atoms was measured in 1920 that Sir Arthur Eddington (1882–1944) proclaimed that nuclear fusion powered the Sun and stars. Hans Bethe (1906–2005) put the whole stellar nuclear fusion process together in 1938 and won part of the 1967 Nobel Prize for physics as a result of his work.

As the early twentieth century progressed we learned more and more about our star, the Sun. A whole branch of astronomy devoted to the Sun was created by George Ellery Hale (1868–1938), and solar observatories were built by him to observe the Sun, most notably on Mount Wilson near Los Angeles, California. As work progressed in the world of quantum mechanics, as you read about in Chap. 2, we began to put the pieces together on the puzzle of what powered the Sun and the other stars. Solar observatories and solar astrophysicists slowly began to learn more and more about our star.

The Sun is classified as a yellow dwarf star that is about 864,000 miles in diameter. It may seem hard to consider our Sun as a dwarf star, but that is the name that was given to normal stars from over a hundred years ago, when a smaller category of larger stars was found to match the colors of the normal stars. There are some really big stellar giants out there in the Milky Way Galaxy that are hundreds of times more massive and larger than the Sun. (More massive stars exist, too, even among the dwarf stars.) The Sun also does not have a companion star, which is unusual, as about 70% of the stars in the Milky Way are multiple-star systems.

The Sun is nearly in the middle of its lifetime of 10 billion years. The Sun converts about 600 million tons of hydrogen into helium every second to power itself through nuclear fusion. It is located about 93 million miles from Earth, and its light takes a little over eight minutes, at the speed of light (186,000 miles or 300,000 km per second), to reach Earth.

When the Sun runs out of hydrogen at its core, as all stars do eventually, it will first develop over time into a red giant star about 100 times its current diameter. At that time the Sun will swell to such a size that it will engulf Mercury and approach the orbit of Venus. After the Sun runs out of helium in its core, it will then swell to about 400 times its present diameter. When that second red giant stage happens the Sun will engulf Venus, Earth and Mars. The outer Solar System planets and their moons may survive for a while during this phase of the Sun’s death, but eventually the Solar System will be a relic of its former self and become what is called a planetary nebula, with a white dwarf at its core. The remnant white dwarf will be about the size of the current Earth.

We’ll explore more on the birth, life and death of the Sun further in Chap. 6, “The Stars.”

The most beautiful times to view the Sun at sea are what one captain calls the “magic hours” of sunrise and sunset. It is then that the Sun reigns supreme. You can get the time of sunrise and sunset off of the ship’s information channel and plan accordingly. You will need to determine the ship’s course in relation to either sunrise in the east or sunset in the west, so that you will know where to position yourself to watch or photograph the event. The colors of the sea, sky and clouds all intermingle to capture our imagination, emotions and gaze. Just remember: NEVER look at the Sun with your eyes or camera without looking through an approved and certified solar filter for your camera’s lens(es) or ISO 12312-2 solar eclipse glasses for your eyes. Remember and follow the safety notes at the beginning of the chapter.

The progression of sunrise and sunset are opposites, of course, but what you are trying to see is the same. If clouds are present but not totally covering the sky they can add breathtaking beauty, especially towering thunderheads as they catch the rays of the rising or setting Sun and shadows from other clouds that may be present. The sky can change hue and color quickly, so be alert and take lots of pictures. Do not forget to include the waves of the sea in your viewing and photographs, as the water can reflect the colors of the sky in undulating fashion. The increasing or decreasing light can really be spectacular when waves and clouds combine.

Do not be too quick to grab a picture of sunrise or sunset and go below. When the Sun is below the horizon it can still illuminate magnificent clouds that are below the horizon creating spectacular shadows in the sky as well as illuminating their cloud tops or any other clouds that are above the horizon. The soon to rise or set Sun can also illuminate cloud tops of thunderheads or other high-altitude cloud formations that are visible to you, even in the east or west. Some of the most spectacular colors you will ever experience at sea arise from the Sun below the horizon illuminating clouds – it can take your breath away.

Check to see if the Moon or any planets will be in the sunrise or sunset sky. This can really add to the beauty of the view and photographs. These specific situations are addressed in Chaps. 8 and 9.

There is also one other sunrise/sunset scenario you want to see and photograph if the ship’s course is right, and that is the ship’s wake.

There is great symbolism in seeing the ship’s wake reflected in the oncoming rays of the new day or the receding shadows of the day that is done. The wake leaves a lengthy trail in the water that can catch the light separate from that of the surrounding water. If you get that right moment when sea, sky and wake combine you will be in awe. If you photograph it you will want to have it in your printed collection. Be sure to check every day if the ship’s course will be somewhere near 090 or 270 degrees so that it will align with sunrise/sunset and allow you to see this.

Astrophoto Tip

For each chapter in Part I dealing with sky objects there is information on how to photograph them. Be sure to read all of Part II before you try to take any photographs, though, as the tips and tricks provided will help to make sure your photographs are the best they can be from a ship underway in the ocean!

Photographing Sunrise and Sunset

You do not want to photograph the Sun itself, just the approach of sunrise or after the Sun has set, for safety reasons. As an extra eye safety measure you can use LIVE VIEW – the camera’s actual lens view as seen on the LCD monitor. NEVER look through the camera viewfinder during these sunrise/sunset sessions. Close or cap the viewfinder window when photographing sunrises/sunsets, just to make sure your eye is not accidentally exposed to the Sun. If your camera doesn’t have LIVE VIEW just aim it in the general area of sunrise/sunset and you’ll do fine.

When photographing sunrise/sunset you’ll probably need to focus at Infinity and can use your lens’ Infinity mark.’ Or, focus on the visible horizon, a distant part of the ship or bright stars, a planet or the Moon if they are visible.

For sunrise and sunset you may also consider letting your camera come up with the recommended exposure; it may even have a sunrise/sunset setting that can help. It can get tricky getting the right exposure when you are trying to combine the light from the sky and the sea. Once again you should use a wide-angle lens to capture as much of the scene as possible. A 35-mm lens pulls in lots of detail while giving good area coverage.

You will have increasing light at sunrise, so, if you decide to try “Manual,” use ISO 800 to 1,000 when it is still somewhat dark, and use a lower ISO as it approaches dawn. Dawn itself is in the ISO 100 to 200 range for typical exposures such as 1/125 s at f/8 or other exposures in the range that would be found automatically.

With ever-decreasing light at sunset, as time goes on you will have to adjust accordingly. You may want to try the “Manual” setting to adjust the exposure to get the right combination. In the deepening twilight start at 800–1,000 ISO. You may even try exposures at 1/2 to 1 second in deep twilight. This is where taking a lot of pictures and adjusting accordingly can get you that perfect shot (Figs. 5.1, 5.2, 5.3, 5.4, 5.5, and 5.6).

Fig. 5.1

Objects viewed: Sky and sea. (Image by the author)

Ship: Masadam

Lens used: 18 mm f/3.5

ISO: 800

Exposure: 1/30 second

Comment: Alternating colors in the sky reflected in the waves

Fig. 5.2

Objects viewed: Sunburst clouds and waves. (Image by the author)

Ship: Masadam

Lens used: 18 mm f/11

ISO: 100

Exposure: 1/400 second

Comment: The Sun is completely covered by clouds, but its rays burst forth through the clouds. This illuminates the undulating waves

Fig. 5.3

Object viewed: Sunset. (Image by the author)

Ship: Queen Victoria

Lens used: 28 mm f/4

ISO: 1250

Exposure: 1/30 second

Comment: The ship Queen Victoria highlights the sunset and clouds in the Atlantic

Fig. 5.4

Object viewed: Sunset. (Image by the author)

Ship: Riviera

Lens used: 200 mm f/6.3

ISO : 800

Exposure: 1/640 second

Comment: A razor-sharp sea horizon and a vessel grace an Atlantic Ocean transit sunset

Fig. 5.5

Object viewed: Sunset. (Image by the author)

Ship: Azamara Journey

Lens used: 72 mm f/5

ISO: 1000

Exposure: 1/400 second

Comment: Clouds during sunset in the Indian Ocean

Fig. 5.6

Object viewed: Sunrise wake. (Image by the author)

Ship: Azamara Quest

Lens used: 14 mm f/2.8

ISO : 800

Exposure: 1/125 second

Comment: Color in the sea and sky abound as the ship was transiting the Great Barrier Reef in the Coral Sea

Astrophoto Tip

Use the SAAS technique for your pictures  – Shoot, Assess, Adjust, Shoot – to maximize getting a good shot. You’ll see later in the book how this comes into play.

The Green Flash

There is yet another phenomenon associated with sunrise and sunset, called the green flash. At sunrise the green flash possibly occurs at the instant the very top limb of the rising Sun intersects the horizon and produces a vivid green-colored flash of light. If you are looking for the green flash, DO NOT KEEP LOOKING AT THE SUN. LOOK ONLY FOR AN INSTANT. Remember the safety warnings at the beginning of the chapter about never staring at the Sun. For sunset it occurs when the very top limb of the setting Sun intersects the horizon and possibly produces a green flash of light. Again, DO NOT stare at the Sun as it is setting, look only for that instant when the tiny sliver of the top limb is disappearing.

The green flash is notoriously finicky to see. The horizon has to be almost razor sharp, with no clouds, haze or fog. Even then there is no guarantee you will see it. You just have to watch when conditions appear favorable.

The green flash occurs because the refraction (bending) of sunlight is different at different wavelengths, so very near the horizon the rays of the Sun are spread out vertically. The bluish light is scattered far away and the yellow is absorbed by moisture in the atmosphere, so when the red limb sets only the green is left to see.

The green flash is also notoriously difficult to photograph. You will need a tripod or bracing from the ship’s structure and at least a 200-mm telephoto lens. You will really need a cable release for this shot as using a delayed shutter exposure setting will almost certainly make you miss the phenomenon. If you do not use this setup your picture will probably be blurred.

When trying to photograph the green flash at sunrise, make sure the camera’s viewfinder is closed or capped off and use LIVE VIEW. If you do not have this feature, aim your camera at the area of greatest brightening on the horizon – that is where the Sun will rise. Take a quick shot to confirm you are at the right spot with proper camera settings and stand ready to take a shot the instant the Sun’s top limb appears and then immediately move the camera off the Sun and look away. There is no second chance. You either got the green flash at the instant the Sun appeared or you didn’t.

For sunset you have to be far more careful with your eyes and camera, as the Sun is above the horizon blazing away and is dangerous to look at – don’t do it! Make sure the viewfinder is closed or capped off and be prepared to use LIVE VIEW for the shot. DO NOT aim your camera at the Sun until the very last sliver of the top limb of the Sun is very close to the horizon. If you do not have LIVE VIEW aim your camera and take a quick shot to confirm you are at the right spot with proper camera settings. Stand ready to take a shot when the very last of the Sun’s limb disappears.

The best way to capture the green flash may be by taking a video using the previously described solar safety rules of the very first (sunrise) or last (sunset) instant of the Sun’s top limb along the horizon. You can then view frame by frame to see if you captured it. It may be subtle or it may be intense – one never knows. That’s why you check each day if the conditions on the horizon are suitable for having a chance at seeing the elusive green flash.

The author’s first green flash photograph was from a video frame showing the phenomenon at sunset as the result of a cloud top along the horizon! (Fig. 5.7).

Fig. 5.7

Object viewed: Green flash. (Image by the author)

Ship: Prinsendam

Lens used: 300 mm f/5.6

ISO : 400

Exposure: 1/800 second

Comment: A rare cloud-top green flash

Seeing Earth’s Shadow

It is recommended that you be out on deck at least 45 minutes if not more before the stated time of sunrise and sunset, as the ship might be off on their time and you will want to take advantage of seeing something else that happens during this magic hour – Earth’s shadow.

Every clear day at sea you have two opportunities to witness our planet’s shadow in the sky. Sometimes it is hard to remember that we are on a planet – a solid and spherical physical astronomical body in orbit around the Sun. Being at sea gives you more of a feel of this as the horizon is close, and you can possibly see ships disappear over the horizon due to Earth’s curvature.

Our planet casts an actual shadow out into space for a distance of almost a million miles. It is this shadow that causes eclipses of the Moon when it enters and exits Earth’s shadow. See Chap. 10 on eclipses for more information. You do not have to wait for a lunar eclipse to see it, as you shall see. It is a very beautiful way to welcome the onset of a new day or the beginning of a night at sea.

Earth’s shadow is subtle, as it begins to develop at sunset and starts to fade with sunrise. It requires a fairly clear horizon and atmosphere to see and is worth looking for each day.

About twenty minutes before sunset you will begin to notice the development of a grayish-blue tint to the sky located along the horizon opposite to where the Sun is setting. As time goes on and nearer to actual sunset you will notice that this band of color grows vertically and along the horizon. The shadow will eventually take on a pinkish band at its top – the Belt of Venus . This feature is the very last of the Sun’s rays of the day passing through Earth’s atmosphere on the western horizon and catching the top of Earth’s shadow.

Following sunset the Belt of Venus will fade, and the shadow band will begin to meld into the darkening night sky. The stars and visible planets will become apparent while this process takes place. You are actually watching nightfall take place.

To see Earth’s shadow before sunrise be on deck at least a half-hour before, then look directly opposite the point on the horizon where pre-dawn lightening is occurring. The shadow is already fully developed with the Belt of Venus, and then both will become fainter as the Sun gets closer to rising. The stars and planets will fade as daylight takes over and another day at sea has begun.

To photograph Earth’s shadow it is best to have a wide-angle lens such as a 14-mm f/2.8 prime or even a fisheye lens that can capture as much of the horizon as possible. You should lessen the fisheye effect post processing if possible. Any lens will work, but here less focal length and wider aperture is better to capture the fullest extent possible of the horizon and the subtle darkening of the shadow and the pinkish Belt of Venus for the shot. Shoot from a tripod or a ship’s structural brace using your shutter cable release or delayed shutter release option if your camera has one to minimize camera movement.

For the pre-dawn Earth’s shadow and Belt of Venus use your fastest f-stop, start at ISO 1,000 with an exposure of 5 seconds . Evaluate your results and adjust accordingly.

For sunset, start at ISO 800 using your fastest f-stop and try half a second. Evaluate your results and adjust accordingly (Figs. 5.8 and 5.9).

Fig. 5.8

Object viewed: Earth’s shadow, Belt of Venus and Moon. (Image by the author)

Ship: Azamara Quest

Lens used: 28 mm f/5.6

ISO: 1000

Exposure: 1/200 second

Comment: Earth’s shadow at sunset, the Belt of Venus, and the rising full Snow Moon are visible in the Torres Straits. The exposure had to be faster than normal due to the presence of the Moon

Fig. 5.9

Object viewed: Anticrepuscular rays, Belt of Venus and full Snow Moon. (Image by the author)

Ship: Azamara Quest

Lens used: 14 mm f/2.8

ISO : 1000

Exposure: 1/600 second

Comment: Wide-angle view of Earth’s shadow at sunset, the Belt of Venus, and the rising full Snow Moon in the Torres Straits are visible, as is Azamara Quest. The exposure had to be faster than normal due to the presence of the Moon

You have to monitor the progress of Earth’s shadow against the progression of sunrise/sunset, as they are happening simultaneously. It helps to be on the top deck if at all possible because this allows you to switch from horizon to horizon fairly quickly to see the shadow and sunrise/sunset and photograph them.

Other Atmospheric Phenomena

The Sun can produce other atmospheric phenomena caused by interaction with clouds, such as rainbows, solar halos and “Sun dogs.” These are covered in Chap. 13. The Sun also drives our planet’s weather, with clouds probably being the most common aspect of this relation that we see almost every day at sea.

You will probably see quite a few clouds on your cruise. During the day they can be majestic, as thunderheads build up, especially in the tropics, and tower overhead at tens of thousands of feet. Watching these monsters grow can be mesmerizing, and if you have some form of optical aid you can actually see the cloud tops billowing higher and higher. You might get puffy clouds or high flying cirrus clouds, all of which can be a pretty sight.

As the ship and clouds move there will be an ever-changing aspect to how the clouds appear. So it may be worth spending some time up on deck cloud watching, especially if you are in the Indian Ocean. The surface can get mirror smooth, which highlights the beautiful blue of the ocean and the sky. Add in a nice cloud formation, and you are making one of those cruise memories (Fig. 5.10).

Fig. 5.10

Object viewed: The Indian Ocean. (Image by the author)

Ship: Nautica

Lens used: 14 mm f/2.8

ISO : 200

Exposure: 1/8000 second

Comment: The mirror-like blue water of the Indian Ocean in daytime plays host to developing thunderheads

For photographs, in daytime you can hand hold your camera to take cloud shots, as there is plenty of light and you will be using a fast exposure. You can use your camera’s “Daytime” program, if it has one, or its automatic exposure setting. You want the wide-angle lens view in order to take in as many of the clouds as you possibly can.

Astrophoto Tip

If your camera can’t focus due to insufficient light at dusk or dawn try focusing the lens on a part of the ship that is furthest away from you or adjust the lens to its “Infinity” setting. Take pictures and change settings accordingly.

If you are photographing clouds along the horizon at dusk or dawn you may want to get the wide-angle view. Then, get in closer with a longer focal length lens in order to highlight a single or a group of clouds, especially if there is a lot of color present. You can use a 300 mm to pull in the horizon, clouds and the color into a frame to fill it completely, as in Fig. 5.4. You will also have to determine how much light there is between the sky, cloud(s) and ocean/horizon. This can be tricky as to ISO setting and focusing. You can go to an ISO setting and use “Manual” to get the best shutter speed to bring out your shot.

You can hand hold your camera to take daytime photos of the sea and clouds, as with these types of shots there is plenty of light, and you will be using a fast exposure. You can use your camera’s “Daytime” program if it has one or its automatic exposure setting. You want the wide-angle lens view in order to take in as much as the ocean and cloud scene as you possibly can. If you are taking shots of tall thunderheads, which can be quite high, you may want to rotate your camera 90 degrees to try and capture the full height of these beautiful cloud formations.

Astrophoto Tip

You may have strong sunlight reflection off of the water , which can affect the metering of your camera, so be on the lookout for this. Your camera may underexpose the whole picture if your metering area focuses on the water’s sunlight reflection, so try to pick an area free of it.

One other thing you may want to do is capture a “shadow selfie” at high noon. A shadow selfie is a neat memory picture that shows your shadow in the water very near the hull of the ship as she goes through the water. You want to take this picture when the Sun is directly overhead (and the Sun is rarely directly overhead and is never overhead unless you are between the Tropic of Cancer and the Tropic of Capricorn), local noon, so that your shadow is projected onto the water’s surface and the rays of the Sun penetrate their deepest into the depths. The shadows and rays of sunlight in the water along with your shadow selfie can look quite remarkable. Add in the color and texture of the water, and this is one pic you will be showing everyone (Fig. 5.11).

Fig. 5.11

Object viewed: Indian Ocean selfie. (Image by the author)

Ship: Nautica

Lens used: 50 mm f/1.4

ISO : 200

Exposure: 1/8000 second

Comment: Shadow selfie and the depths of the Indian Ocean

Next up are the Sun’s relatives, the stars.

© Springer Nature Switzerland AG 2018

Gregory I. RedfernCruise Ship Astronomy and AstrophotographyThe Patrick Moore Practical Astronomy Serieshttps://doi.org/10.1007/978-3-030-00958-8_6

6. The Stars

Gregory I. Redfern1  

(1)

NASA JPL Solar System Ambassador, Ruckersville, VA, USA

Gregory I. Redfern

Seeing the stars from a darkened ship at sea is something everyone who loves the sky or cruise ship guests should experience at least once in their lives. During the cruises the author has been on as a lecturer, when the weather permits – and this is a big factor for both visibility and safety reasons – I have had guests attend my “At Sea under the Stars” presentation. This is a chance for guests to see the stars on a darkened ship at sea and learn about them and their influence on navigation, culture and civilization in general. This is always touted as a highlight during the cruise by those that attend.

As you have learned, the time of year and your location determines what stars you can see. The phase of the Moon is also a major factor as to how many stars you can see, as the amount of moonlight present can really reduce the visibility of the stars (see Chap. 9). As the Moon goes through its monthly phases you have to take this into account as you plan any stargazing or astrophotography sessions. Whether it is the Moon that is your primary interest or the stars you have to be aware of the Moon’s phase and location in the sky. For maximum sky darkness a new Moon is best, with a few days before or after this phase. Your software is a real advantage here over a planisphere or star charts, as you get real-time positioning of the Moon in the sky set against the constellations and stars present.

On a dark summer’s night in the Northern and Southern Hemispheres you can see a sky full of bright stars highlighted by the Milky Way running through them. The bright stars of the winter sky dominate the view, with a much dimmer Milky Way. The actual number of individual stars you can see with your eyes at sea depends on the transparency of the sky, the lighting conditions on the ship, time of year, your location and your own quality of eyesight. Viewing the stars is where the use of an optical aid, especially something like the Vixen 2.1x42 binoculars, come into their own. A wide view with excellent optics equals unparalleled views. Everyone who has looked through them has been really impressed.

What of the stars themselves? We know that the Sun is a star and directly related to those we see in the sky. We discussed nuclear fusion as the power source of the stars, but how do they come to be? How do they die? Why do the stars have different colors and varying levels of brightness? Are stars grouped together in the sky? Good questions, and astronomers have determined the answers.

All stars are born, live and die. How long they live is determined by just one physical property – how massive they are. Astronomers measure stellar masses in relation to the mass of our own Sun, which is one solar mass. The more massive you are as a star the faster you burn up your hydrogen gas at your very core. The less massive you are, the longer it takes you to go through the hydrogen gas at your center. So a low solar mass star of say a tenth of a solar mass will live for at least a TRILLION years! Contrast that to a star of 10 solar masses, which will live only about 32 million years or if you are a real beast of 60 solar masses, 3 million years!

Think of this analogy when it comes to how stars expend their fuel – hybrid car versus a sports utility vehicle (SUV). The hybrid is miserly when using its fuel, as it is a small, light fuel efficient car with a small engine that gets great mileage out of every gallon of gasoline and tankful. Huge and heavy SUVs, with a very high horsepower engine, go through fuel like there is no tomorrow due to low miles per gallon and poor fuel economy.

Regardless of a star’s mass they are all born the same way – from a huge cloud of gas and dust called giant molecular clouds, or GMCs. They are seen in the Milky Way Galaxy and other spiral-type galaxies, as large amounts of gas and dust are contained in their spiral arms, all of which will lead to future generations of stars. Elliptical galaxies do not have much if any gas and dust or GMCs, so their star-making days may be done.

Nestled within galactic spiral arms these GMCs can be seen as a nebula (nebulae for plural). There are two other primary types, bright emission nebulae and dark (absorption) nebulae.

Bright emission nebulae are visible due to the powerful radiation from newborn stars in the nebula ionizing the gas there. It is usually a red color caused by the hydrogen gas present. This stellar ionization is the same process by which fluorescent bulbs work except that it is electricity flowing through the gas in the bulb that causes it to shine, not intense starlight. The color that is emitted by the nebulae or fluorescent bulb is dependent on the gas element present, hydrogen, helium, oxygen, etc.

Dark (absorption) nebulae are very thick due to gas and lots of dust that absorb starlight. Star formation takes place deep within their cold interiors, which we can observe using radio telescopes to penetrate the nebulae and optical telescopes observing in infrared wavelengths that sees heat signatures within the nebulae.

We can see both types of nebulae in the night sky at sea with our own eyes and in binoculars, most famously the Orion bright emission nebula (M42) in winter, the numerous emission nebulae in the center of the Milky Way during summer, and the dark nebulae along the Milky Way arms, especially the Coal Sack in the Southern Hemisphere – near the Southern Cross – and the Northern Coalsack – near Deneb in Cygnus – as well as the Great (or Dark) Rift in the Northern Hemisphere.

Astronomers have pieced together how stars are born within these GMCs by using their knowledge of nuclear fusion in stars, computer models of star formation and comparing their results with actual observations of GMCs and newborn stars.

GMCs can span many light years and contain thousands to millions of solar masses in gas and dust – the raw material for making stars, and as we shall see in Chap. 8, planets and solar systems. GMCs are generally very diffuse, but when some sections of the gas and dust present in them are affected by passing stars, a supernova shockwave or some other form of turbulence in the nebula, it can cause areas of higher density to form.

If the density gets high enough the gas and dust can start to undergo gravitational attraction that over time accumulates enough gas and dust to eventually form a large globule, or knot. Within this globule several areas of gas and dust can reach sufficient mass to begin to fall inward under the influence of gravity and undergo gravitational contraction, eventually taking on an overall spherical shape and heating up.

As this contraction continues, at the very core of the shrinking star to be, the temperature, pressure and density begin to significantly rise, creating a protostar. Sun-like protostars can be over 20 times the diameter of today’s Sun. This new protostar will continue to contract and heat up its central core, eventually reaching about 18 million degrees Fahrenheit, at which point nuclear fusion begins and a new star is born.

It takes some time for the new star to adjust, as it can undergo periods of variability and intense stellar winds until it settles itself. At this point the star has reached hydrostatic equilibrium, which means the outward radiative pressure caused by the nuclear fusion at its core and the inward crush of gravity caused by the mass of the star are in balance. A star lives as long as this equilibrium (balance) is maintained. Gravity’s crush is always present and ready to win this tug of war, which it does for massive stars in an explosive way, as we shall see.

For stars like the Sun this stellar birth process can take about 50 million years, for more massive stars about 100,000 years and less than solar mass stars 100 million years. The new star will eventually erode away its cocoon of remnant gas and dust to emerge. A thousand stars can form in a section of a large GMC and become a star cluster, arguably the most famous being the Pleiades (also known as the Seven Sisters Star Cluster, M45) in Taurus the Bull. This beautiful cluster, which resembles a little dipper – not to be confused with the far larger Little Dipper in the north – can be easily seen with the unaided eye in winter. The bright, young and hot stars of the Seven Sisters are still enveloped in their celestial womb of gas and dust that can be seen in long-exposure photographs taken on land.

For the duration of their lives all stars do three things: they generate light and energy and make the chemical elements of the universe. Most people know about the first two, as we can see this in the light and heat from the Sun. But the third result from stars, the creation of the natural elements beyond hydrogen – which was formed in the Big Bang – comes as a surprise. The nuclear fusion process burns hydrogen to make helium, which then goes on to make other chemical elements in gaseous form, a process known as stellar nucleosynthesis.

All of the natural chemical elements on the Periodic Table of Elements beyond hydrogen are made during the lives and deaths of stars. As you learned, how long stars live depends on how massive they are. Their mass also determines how they will die. Stars like the Sun, up to about 8 times its mass, and less massive stars about a third as massive, will undergo a prolonged and relatively quiet dying, making lighter elements in their lifetime and death. For stars more massive than 8 solar masses and higher the end comes quick and explosively, making heavy elements during their lifetimes and having spectacular deaths.

Stars like our Sun live about 10 billion years before they die. The Sun is currently burning about 600 million tons of hydrogen into helium each second, which will ultimately use up the hydrogen at the nuclear core, leaving a core made of helium.

The Sun’s core will not be hot enough initially to burn this helium, and nuclear fusion stops at the core. With the outward radiative pressure from nuclear fusion at the core gone, gravity begins to make the Sun contract, raising the interior temperature of the Sun sufficiently high to ignite the thin layer of hydrogen that surrounds the Sun’s core. This outward radiative pressure expands the outer atmosphere of the Sun, causing it to become larger, cooler and redder. The Sun has now entered the red giant phase of its life, which will last for about a billion years.

With the nuclear fusion process at the core temporarily stopped once again gravity makes the core contract and thereby raises the temperature to 100 million degrees. This is sufficient to burn the helium in the core and in the process make carbon and oxygen, which begin to accumulate in the core as the helium is depleted. A layer of helium forms around the core, joining the already present hydrogen layer. When the helium is expended in the core and carbon and oxygen remain, the core again contracts but will never reach the required 600 million degrees necessary to burn carbon. Nuclear fusion ceases. With no outward pressure from nuclear fusion the core contracts due to gravity and heats up.

When the core reaches a certain diameter, about the size of Earth, the density of the core is sufficient to produce electron degeneration. At this point the electrons in the core of the Sun can no longer be compressed, as there is nowhere for them to go, and the Sun has become a white dwarf star – a 100,000 degree stellar corpse that will slowly radiate away its heat into space.

While all of this has been going on in the core the outer layers of the Sun have been expanding outward. These contractions of the core have made the Sun unstable, and the outpouring energy has really expanded the Sun out to 400 times its original diameter, more than enough to consume Mercury, Venus, and in all probability Earth and Mars. The higher temperatures of the Sun will have destroyed Earth long before it is consumed by its expansion, as the oceans and atmosphere will have been vaporized and the surface become molten.

The outer Solar System may reap the billion-year benefit of a red giant Sun by enjoying higher temperatures and sunlight, perhaps enough to melt icy surfaces that we see on the moons of Jupiter and Saturn into liquid water oceans. Could life evolve in the time remaining?

The dying Sun will undergo spasms that will eventually push its outer layers completely away from it, revealing the white dwarf that remains – a process that will take about 75,000 years to complete. After billions of years the white dwarf will eventually cool to become a black dwarf that is thought to possibly have a solid surface made of carbon due to being exposed to extreme heat and pressure – the conditions necessary to form a diamond. The universe is not old enough for black dwarfs to have formed – yet.

This ever-expanding cloud of gas and prevalent dust is made up of those layers of hydrogen, helium, carbon and oxygen that the Sun manufactured during its life. The consumed planets of our Solar System are part of this expanding planetary nebula, so named because early astronomers that saw these nebulae in a telescope thought they looked like planets. We see many planetary nebulae in our Milky Way Galaxy, as the powerful radiation from their white dwarf star ionizes the dead star’s gases into colorful splendor. Each element reveals its identity from its color.

Even though planets are destroyed and their remnant solar systems doomed to eternal blackness due to the death of their parent solar mass-sized star, the elements they created in their lives and deaths survive. They are in the expanding planetary nebulae that will seed giant molecular clouds and nebulae to bring forth new stars, new planets and, perhaps, new life in our Milky Way Galaxy.

However, if the white dwarf is part of a binary-star system – two stars that orbit a common center of gravity and are gravitationally bound to each other – and is close enough to its companion star to draw matter from it, a far different fate awaits it. Such a white dwarf will not go quietly into the night. A violent destiny awaits it that will involve either periodic explosive outbursts as a nova – Latin for “new star” – or complete and total destruction as a supernova.

A white dwarf will remain stable for billions of years unless it is close enough to a companion star to gravitationally attract gas, mostly hydrogen, from that star’s outer atmosphere. Over a period of time this gas ends up adding to the mass of the white dwarf. If it reaches sufficient mass the gas on the white dwarf’s surface will undergo an explosive outburst of nuclear fusion that can release the equivalent energy output of the Sun for 10,000 years or more – a nova. The white dwarf that has become a nova can increase its brightness by 1,000 to 10,000 times. A once obscure star now might reach naked-eye visibility. This outburst can last for days to weeks. It is estimated that at least fifty novae occur each year in the Milky Way Galaxy.

Astro Tip

When a bright nova reaches naked-eye, binocular or telescope visibility viewing alerts are put out by popular astronomy outlets. You should subscribe to EarthSky.​org, skyandtelescope.​com or astronomy.​com to receive such e-mail notices on comets, novae and supernovae so you can observe and photograph them.

If the white dwarf’s mass exceeds 1.4 times the mass of the Sun, known as the Chandrasekhar limit (named for the Nobel Prize-winning astronomer who discovered this) the carbon and oxygen in the core undergo uncontrolled nuclear fusion. This runaway fusion completely destroys the white dwarf except for the elements it had formed in the core and those created in the supernova explosion. This spectacular white dwarf supernova explosion, called a Type Ia (or b) Supernova, outshines all the stars in its parent galaxy and can be seen in distant galaxies.

Another type of supernova, a Type II, occurs in stars more massive than 8 solar masses. For them a far more violent and abrupt end awaits after their short stellar lives, even though they were born in the same manner as the Sun. They, too, become red giant stars in the final phase of their lifetimes, but do so much quicker than the Sun, on the order of millions of years not billions. They make elements just like the Sun does through nuclear fusion, but because they are more massive their cores burn much hotter, which enables them to make more chemical elements, including silicon, which results from the fusion of oxygen. These fusion-created elements each form an onion-like layer around the core of the massive star.

A star 25 times the mass of the Sun will spend 7 million years burning hydrogen into helium and 6 months burning oxygen into silicon. Next up is the creation of iron from the fusion of silicon in the core at about 4.8 billion degrees Fahrenheit, but that lasts only a day! When iron forms in the core of any massive star it has only seconds to live. The presence of iron in the core of a massive star stops nuclear fusion because iron needs to absorb energy for fusion to take place. With no outward radiative pressure due to fusion, gravity wins in a big way.

The core collapses in on itself in less than a quarter of a second, with the core temperature reaching over 180 billion degrees Fahrenheit. The core collapses until it reaches nuclear density, making neutrons in the process and making it very difficult for the core to contract any further due to the strong nuclear force. Core contraction stops, and the core actually rebounds, producing an outward moving shockwave that a split second later intercepts the collapsing onion-like layers of elements in the star and reverses their direction.

The expanding shockwave works its way through the star, creating elements heavier than iron in the process and finally reaching the outer layer of the star in a couple of hours. This causes the star to explode, becoming a hundred million times brighter than it was before – a Type II Supernova . The shockwave disperses the newly created elements out into interstellar space to enrich dust and gas clouds. The shattered star will eventually become a supernova remnant. We see many supernova remnants in our Milky Way Galaxy.

The core that remains after the star goes supernova has its fate determined by the amount of mass that remains. If the core is 1.4 to 3 solar masses it will become a neutron star, a stellar corpse the size of a city that has neutrons so densely packed that a sugar cube made of this material would weigh a billion tons!

All neutron stars are thought to have a solid surface and rotate rapidly – the fastest known pulsar (see below) rotates over 716 times a second – when they are very young – and have extreme magnetic fields that are TRILLIONS of times more powerful than Earth’s. These magnetic fields channel out high amounts of energy as a rapid pulse which, if oriented towards Earth, can be observed as a pulsar. These pulses are extremely precise and unique in their spin rate, so much so they are being studied to become the next generation of space navigation tools and have been used as ultra-precise clocks.

We have detected less than 2,000 pulsars in our Milky Way Galaxy, whereas there are probably a billion in the galaxy. For many of these we do not intercept their pulses, while others have dimmed over time to the point where their pulses are too weak to be observed. So far there have been twenty pulsars observed beyond the Milky Way Galaxy in the Large and Small Magellanic Clouds. Radio astronomers are currently searching other galaxies for pulsars.

Some neutron stars can have magnetic fields that are a thousand times stronger than regular neutron stars and are called magnetars. All neutron stars’ magnetic fields and solid crusts are closely interrelated. When there is a shift in the solid crust – a starquake – it unleashes an almost unimaginable amount of energy through the magnetic field. In one such starquake an equivalent amount of energy produced by the Sun in 100,000 years was unleashed in just one-tenth of a second!

Neutron stars were at the center of astronomical history as we briefly discussed in Chap. 2 when on August 17, 2017, the new age of Multi-Messenger astronomy was born. It occurred when the first-ever detection of two neutron stars merging – a kilonova – was observed as gravitational waves and just two seconds later in visible light and high energy gamma rays. The subsequent light glow from the merger/kilonova was observed by telescopes around the world and in space. Based upon their observations astronomers determined that the kilonova produced 16,000 times the mass of Earth in heavy elements and tens of times the mass of Earth in gold and platinum. All of these elements were blown out into space in an element-laden debris cloud that will seed new stars and planets that form from giant molecular clouds just like happened in the formation of our Sun and Solar System 4.6 billion years ago.

One remaining mystery is, what was left after the merger? Did the two merging neutron stars create a more massive neutron star? Or did they combine to produce the final type of stellar corpse, which we will now discuss.

As bizarre as all of this seems for neutron stars – and it is – we can get an even more astounding result after a supernova explosion called a black hole. If the remnant core of the supernova is over 3 solar masses nothing can stop the gravitational collapse of all that mass; it simply disappears from our reality into something called a black hole singularity. Einstein’s Theory of General Relativity predicted black holes and their singularities, where a finite mass is compressed to zero, producing an infinite density, mathematically speaking. Also, the gravitational field of a black hole is so strong that once you get to a certain point, called the event horizon, nothing, not even light, can escape – hence the name ‘black hole.’

So how can you detect something that emits no light? Astronomers knew that black holes had to exist because of Einstein’s theory and our knowledge about stars, so when the first X-ray detectors were launched into space the hunt was on for X-ray sources. Black holes were predicted to reveal their presence in a binary-star system, due to their immense gravity pulling on a close stellar companion. Sound familiar? This gas from the companion star would be accelerated to very high speed, high enough to make the gas very hot and emit X-rays before swallowed by the black hole at the event horizon.

Sure enough, a very powerful singular X-ray source called Cygnus X-1 was catalogued in 1964 and observed with visible light telescopes. These observations revealed the presence of an ordinary star, with nothing seen at the coordinates of the X-ray source. The very first suspected black hole had been found. If it wasn’t a black hole producing the X-rays astronomers had no clue as to what else it could be.

More black hole candidates were found and catalogued over the next decades, but they remained unproven until the gravitational wave observations we discussed in Chap. 2 proved their existence. Astronomers have confirmed several other black hole mergers due to gravitational waves, and more will undoubtedly be found in the coming years. It is estimated that there may be as many as 10 million to a billion black holes in our Milky Way Galaxy based on the number of stars that we observe that can produce them.

There are two other types of predicted non-stellar black holes: primordial and supermassive black holes. Primordial black holes are associated with the Big Bang and are predicted to be the size of an atom with the mass of a mountain. They are very hypothetical and are based on our current knowledge of the Big Bang; we have never observed any natural processes that could be attributed to their influence.

Supermassive black holes on the other hand reveal their presence in the cores of almost all of the galaxies we observe, including our own, as we shall see in the next chapter. These galactic beasts can have millions to billions of solar masses, and astronomers once again deduce their existence due to the observed motions of stars and gas at the cores of galaxies. At the time of writing this book the world is awaiting proof of supermassive black holes in the form of photographs taken of our galaxy and M87 using the Event Horizon Telescope (EHT).

The EHT combines observations from radio telescopes located around the world in order to obtain the size of Earth equivalence of a single radio telescope dish. With such capability it is predicted that the supermassive black hole thought to be at the core of our galaxy and M87 will be imaged and prove their existence. What astronomers think we will see will be very similar to what stellar black holes are thought to look like – a silhouette formed by the intense gravity of the supermassive black hole warping the light from infalling hot gas that exists in the core of the galaxy being observed. If EHT is successful, and it is a massive computing project to combine the data from all of the radio telescopes involved, humanity will have proof positive of the existence of these objects.

You now have a pretty good working knowledge of the lives and deaths of stars. But what do we see when we look up at the stars at sea? With light pollution from onshore sources being non-existent most times, when you find your dark place on the ship the view is incredible on a cloudless and moonless night. You can potentially see thousands of stars of various levels of brightness and colors that have a story of their own to tell. For you trivia fans there are 9096 stars visible to the eye based on a very dark sky site and seeing stars to magnitude (we’ll discuss this shortly) +6.5 – the threshold for visibility with the eye alone. A rough estimate for each hemisphere is 4045 stars, and as you have learned your location on Earth determines what you can see.

The brightest star in the nighttime sky is Sirius, in the constellation (more on that in a moment) Canis Major. It is an extraordinary sight to see as it twinkles near the horizon and rises or sets, which is how it got its name, which means glowing fiery or scorching in Greek. Many unidentified flying object (UFO) reports have been attributed to Sirius and Venus when they are close to the horizon, as they seem to move and change colors to the untrained eye.

Sirius is only 8.4 light years – how far light travels in a year at the speed of light, 186,000 miles per second, or 300,000 km per second – distant, which means that when you see it, subtract 8 years from the current date and you have the year the light you are seeing left the star. For instance, look at Sirius in 2019 after reading this chapter. The light from Sirius that enters your eyes and travels along your optical nerves to stimulate the visual cortex of your brain, left in the year 2011. It has been traveling at the speed of light since it left Sirius, a distance of over 48 trillion miles (6 trillion miles in a light year).

Each star that we see at night resides in our Milky Way Galaxy, as we can see no individual stars outside of it with our unaided eyes. Notice how the stars have different levels of brightness regardless of the time of year we are looking at them? Is this a good indicator to determine which stars are closest to us? That is, the brighter they are the closer they are to us? The short answer is “no.”

The closest star to Earth beyond our Sun is in the Southern Hemisphere constellation Centaurus and is a red dwarf called Proxima Centauri. It is only 4.23 light years from Earth, but you cannot see it with your unaided eye. Proxima has two bright companion stars, Alpha and Beta Centauri, which together form a triple-star system. We really cannot determine how close those stars are or how luminous (energy output) just by looking at them. Today we use a system of apparent and absolute magnitude to help us out.

Apparent magnitude, known by “m,” was initiated by the Greek astronomer Hipparchus (190 to 120 b. c.) in about 129 b. c. to denote the levels of brightness of stars in his star catalog. The brightest stars were 1st magnitude, while the dimmest viewable were 6th magnitude. Ptolemy adopted this system in a. d. 140 for his star catalog but added the words “greater” and “smaller” to distinguish between stars that were in the same magnitude range. This system stuck around for 1,400 years, until Galileo observed stars in his telescope that were not visible to the unaided eye and called them stars of the seventh magnitude. Well, as telescopes got more powerful with ever dimmer stars being discovered and the magnitude scale moving farther down the numerical line, the magnitude system had to be modified. In the mid-nineteenth century it was determined that a first magnitude star was about 100 times brighter than a 6th magnitude star, so each magnitude was a brightness difference of about 2.5 times.

When all was said and done some stars and Solar System objects were found to be of zero magnitude and even brighter: Sirius is −1.4 magnitude, Venus –4, the full Moon −13 and the Sun −26. The Hubble Space Telescope can detect objects as dim as 28th magnitude or dimmer. Again, these are all apparent magnitudes.

To determine the true brightness or luminosity of stars (comets and asteroids have their own absolute magnitude system) astronomers established a system of absolute magnitude denoted by “M.” In this system the luminosity or true brightness of all stars was calculated for a standard distance of 10 parsecs, or 32.4 light years. When stars’ levels of brightness are compared on this scale it is really enlightening. Sirius would no longer be the brightest star in the night sky, as it would be +1.4. Our Sun would be visible at a dim +4.5. Rigel would be a stunningly bright −8, with Betelgeuse coming in second place at −7. Your software can give you the m and M values of the stars in the sky. Star charts and planispheres show apparent magnitudes only and are designated by different-size “stars.”

Stars in the sky and in photographs show colors – white, blue, red, orange, yellow. The ability to see these colors is restricted to the brighter stars when it comes to your eyes, but the lens of a camera can capture the color of the stars quite well. The stars get their color from the temperature at their surfaces. Think of a match. When you strike it you can see the colors of orange and yellow. The hot coals in a barbecue or a log in a fireplace glow in reddish color. Your gas stove burns blue. Temperature increases from the colors red to orange to yellow to white to blue. The same is true in the sky; a blue star’s surface is hotter than a yellow- or orange-colored star. Blue-colored stars are the hottest.

Putting all of this together are the 88 constellations of the entire sky, Northern and Southern Hemispheres. Established through antiquity by each of the civilizations and cultures that have inhabited Earth their respective stories have been placed in the heavens above. Their heroes, their demons, their implements from everyday life – all have found their way to becoming stories among the stars. Ancient Greeks, Romans, Chinese, Arabs, and modern humans have all placed in the stars stories to tell and sights to see.

It became necessary to standardize the names and boundaries of the constellations so that objects located and discovered within them could be officially and universally recognized and located. In 1930 the International Astronomical Union (IAU), which has the authority to name all astronomical objects (among other things), formally established the constellation boundaries. The IAU adopted Latin names for the constellations, many of which came from Ptolemy’s star patterns and others from more modern origins. All have a three-letter abbreviation, and once again your software can provide you with the names and boundaries of the constellations as well as their histories and famous objects contained within each of them. Star charts will give you actual constellation boundaries and a legend for the approximate magnitudes of the stars, type of objects contained within them, while planispheres provide a rudimentary outline and very approximate magnitudes.

Photographing the Stars

Your first decision in photographing the stars and constellations is, what do you want to photograph? Individual stars or whole constellations? Your choice determines what type of lens you want to use. In either case you will want your lens at full aperture, and you will probably have to focus manually, as your camera’s autofocus will have trouble honing in on such a possibly small and dim target.

For individual stars you can actually use a telephoto lens to zero in on them to capture their color and fill more of the frame. This necessitates the use of a tripod or bracing on the ship’s structure, as you will never be able to hold the camera steady enough, even on land, to make a star shot appear steady. But if you go this route the star should be bright and no less than 3rd magnitude, though that might be pushing it based on sea and wind conditions. Keep your ISO high so that you can take a fast exposure to minimize not only the motion of the ship but the rotation of Earth as well. With a zoom or telephoto lens it takes only a second or two depending on the focal length of your lens – the longer the lens the quicker the motion from the sea and Earth becomes noticeable – to make your photograph “trailed” or “wobbly” stars. Both Earth and sea will combine to make your picture look like an EKG if you take too long of an exposure (Fig. 6.1).

Fig. 6.1

Objects viewed: Venus and the Milky Way. (Image by the author)

Ship: Liberty of the Seas

Lens used: 18 mm f/4

ISO: 3200

Exposure: 40 seconds

Comment: The author’s first at-sea astrophotograph. Hand-held, way too long an exposure. But, Venus and the Milky Way are visible

Shoot your picture and assess the results. A combination of ISO and exposure should work eventually (Fig. 6.2).

Fig. 6.2

Object viewed: Sirius, the brightest star in the night sky. (Image by the author)

Ship: Nautica

Lens used: 50 mm f/1.4

ISO: 3200

Exposure: 4.2 seconds

Comment: Sirius and Canis Major, including star cluster M41 below Sirius, taken in the Indian Ocean

If you want to photograph whole constellations you will need a tripod or ship’s structure bracing for the same reasons as shooting individual stars. You have to determine how large your target is, as some constellations such as Cancer the Crab are very small in the sky, while others, like Cetus the Whale, are very large. You can use a wide-angle lens or a medium focal length lens such as a 35 mm or 50 mm to get really decent constellation shots.

You can get an idea of how large the constellation is by setting your software to highlight the constellation when you click on it. You can then see how far it covers in azimuth and altitude by approximating how many degrees it covers along those reference points. Remember that azimuth distance in degrees from cardinal point to cardinal point is 90 degrees, e.g., south to east, while horizon to halfway up in altitude is 45 degrees.

Your camera and lens specifications should show how large of a field in degrees they cover to see if the constellation of interest will “fit.” Remember also that wide-angle lenses cover more sky, but the image will be small. If you try to shoot dim and long constellations with a wide angle, if sea and wind conditions allow, you might be able to take an exposure of 30 seconds.

To photograph the stars your best bet is to get out on deck on a dark, clear and moonless night and shoot the night sky. Take a shot and assess. As you will see, the more shots the better.

Up next is the realm of the galaxies. At sea we have an up close and personal view of the Milky Way Galaxy and others.

© Springer Nature Switzerland AG 2018

Gregory I. RedfernCruise Ship Astronomy and AstrophotographyThe Patrick Moore Practical Astronomy Serieshttps://doi.org/10.1007/978-3-030-00958-8_7

7. The Milky Way and Other Galaxies

Gregory I. Redfern1  

(1)

NASA JPL Solar System Ambassador, Ruckersville, VA, USA

Gregory I. Redfern

In Chap. 6 we learned about the stars and that all individual stars we see are contained in our home galaxy, the Milky Way. It has been estimated that 80% of the people who live in North America cannot see the Milky Way due to light pollution. At sea the opportunity to view the Milky Way in all its glory is a real possibility, depending on the time of year , the phase of the Moon, your location, how bright the ship is and weather conditions.

Astro Tip

If you have software the outline of the Milky Way against the sky should be one of the options available to you. If so, select it and then input your location, date and time to see what the Milky Way should look like in the sky. You can do this if you are already at sea or in advance if you are checking on a possible cruise or planning for an actual cruise. Use the date/time feature to advance the view by hours and/or days, months to see how the Milky Way changes in the sky. It is spectacular at almost any location on Earth but really takes on an awesome splendor “down under” and higher southern latitudes.

Galaxies are the building blocks of the universe in that they produce stars, planets and solar systems. They are the cosmic graveyards to untold numbers of supernovae remnants, neutron stars , black holes, planetary nebulae , white dwarfs and someday black dwarfs. Galaxies are almost as old as the universe itself, based upon the ages of the oldest stars they contain. Our Milky Way has been determined to be about 13.6 billion years old, which would be only about 200 hundred million years younger than the age of the universe. Our galaxy is a barred spiral galaxy with a cigar shaped structure in its center with four spiral arms and smaller spurs curving out and away. What a sight it would be to see from other nearby galaxies.

We have been able to go back in time with the Hubble Space Telescope (HST) and see young galaxies formed shortly after the Big Bang. With the follow-on space telescope to the HST, called the James Webb Space Telescope , astronomers are hoping to see the very first stars and galaxies to form. We still do not have a solid understanding of how galaxies form, but we have some ideas. We are also in a “golden age” of discovery about our own Milky Way, due to some very recent discoveries, as you shall see.

Galaxy formation is kind of like the question of which came first, the chicken or the egg? We know stars are a key component of galaxies, but did stars form first in what would become the core of galaxies or were there large clumps of matter that formed clusters of stars, which then started to gravitationally attract other cluster of stars that then underwent a merger to become even larger? What part did the all-pervasive dark matter play in this?

When the Milky Way Galaxy was first forming billions of years ago the universe would have been a lot smaller and far denser with regular and dark matter than it is now after 13.8 billion years of expansion and evolution. It is an almost foregone conclusion that mergers of star clusters and black holes would have been very common in the early universe. Gravitational attractions between clumps of matter in any form – gas, dust, stars, black holes, dark matter – would have been far stronger then.

We also know that galaxies undergo complete mergers because we see thousands of galaxies in the universe that are colliding with one another due to their mutual gravitational attraction to become a new and larger galaxy. These mergers can be of large galaxies and the satellite dwarf galaxies that orbit them or mergers of large galaxies.

The Milky Way Galaxy is also known to have absorbed (or cannibalized) many dwarf galaxies to become larger in its past and is still doing so now. Astronomers have found remnants of dwarf galaxy mergers in our own galaxy during surveys. But because of the ESA’s ongoing all-sky Gaia star mapping mission, we are learning a lot more about our galaxy – the beginning of a true golden age that will tell us much. As of April 2018 Gaia has amassed data on over 1.7 billion stars to date and provided us with the most accurate map yet of the home galaxy. Astronomers have been able to deduce that the mass of our galaxy is over 1.5 trillion solar masses; this includes the dark matter in the galaxy’s halo.

Thanks to Gaia there is also much evidence in the form of stellar streams that flow into and around our galaxy to indicate that there have possibly been many such occurrences of galaxy-absorbing clusters of stars and small dwarf galaxies. Astronomers have previously catalogued about 50 dwarf galaxies that are gravitationally tied to our galaxy.

Computer simulations that show how our galaxy might have formed and evolved reveal that there should be hundreds of dwarf galaxies orbiting the Milky Way. Perhaps they were there prior to being assimilated. The largest of these stellar streams is being studied by one group of astronomers because it appears that individual stars in the stream are being perturbed by patches of unseen dark matter; such a study could help map the dark matter in our galaxy. Gaia has also revealed many previously unknown substructures in the galaxy which may provide clues to the Milky Way’s past history.

As to large galaxy mergers, our own beloved Milky Way Galaxy is living on borrowed time. Every hour, we are 250,000 miles closer to merging with the other large galaxy in our part of the neighborhood, the Andromeda Galaxy (Fig. 7.1).

Fig. 7.1

Object viewed: Andromeda Galaxy. (Image by the author)

Ship: N/A

Lens used: 300-mm f/4

ISO : 1000

Exposure: 120 seconds

Comment: Andromeda Galaxy with two of its satellite galaxies. Camera was mounted on a telescope mount and tracked. Picture was published online by Space.​com

Yes, that famous galaxy used by Edwin Hubble and Vera Rubin is closing in for a galactic smash up with us. In a few billion years the gravitational attraction between these two large galaxies, which have a combined solar mass of over 3 trillion times that of the Sun, will begin to warp and pull apart the stately spiral arms of each other to start their merger. The new galaxy that will emerge in about 5 billion years from now already has a name – Milkomeda or Milkdromeda. As we know from Chap. 5 the Sun will be dead by then, as will Earth. What’s left of the Solar System may be gravitationally flung farther out into the galactic suburbs. It is not expected that individual stars or their solar systems from each galaxy will collide, as there is a lot of space between stars. Remember, the closest star to the Sun is over 25 trillion miles away. But there may be a merger of another and colossal type that we will discuss in just a bit.

Based on computer simulations Milkomeda will probably become a massive elliptical galaxy, devoid of the stately spiral arms of both galaxies that were gravitationally disrupted due to the merger. It is expected that the merger will result in a frenetic period of star formation, as these two beasts with all of their gas and dust collide, gravitationally mingle and eventually merge. This is what we see in other galaxies that are undergoing various stages of merging. What a sight that will be when that happens. It will also likely be the end of new star formation in Milkomeda, as it is very likely that all of the gas and dust will be used up in the billion-plus-year merger.

Complicating this whole question of galaxy formation and mergers is the fact that in almost every galaxy we look at there is a supermassive black hole residing in their center. We learned in Chap. 6 that black holes are formed when very massive stars become supernovae, and their massive remnant cores collapse to the point where nothing, not even light, can escape their grasp. To form supermassive black holes – some of which are billions of solar masses – some similar process has to occur. We know that all black holes, whether they are stellar or galactic in nature, grow larger in terms of their event horizons – the point of no return for matter or light to escape – and more massive from mergers with other black holes or the infall of other types of matter. So this is a very possible scenario for how such supermassive black holes form.

Our own Milky Way Galaxy has a 4.4-million solar mass supermassive black hole at its center called Sagittarius A* – abbreviated as Sgr A* and pronounced “Sagittarius A Star.” It has been monitored for several decades by astronomers using telescopes and spacecraft. If Sgr A* should become active – i.e., “eating” or absorbing some poor planet, star, gas cloud or other too close to survive cosmic interloper, we would know about it. Our spacecraft that monitor the sky for high-energy outbursts would detect such an event, and astronomers worldwide would be on the case. We also can “see” the center of the galaxy and the area around Sgr A*, thanks to the ability to observe the galactic center using radio telescopes and optical telescopes with infrared capability. Radio telescopes can observe the radio signals given off by gas and molecular clouds in the galactic center, while in the infrared we can pierce the dust and gas between us and the galactic center to observe individual stars.

Astronomers have been watching the orbits of the several dozen stars that orbit Sgr A* for decades , and that is really how they deduced its presence. By calculating the orbital speeds of these stars and following their motions in their orbits around the center of the galaxy it was obvious that a supermassive black hole was present. Like Cygnus X-1 there was no other known explanation to account for what was observed. As we discussed in Chap. 6 the world is awaiting the first ever picture of Sgr A*, taken with the Event Horizon Telescope.

As of this writing in May 2018 new research using NASA’s Chandra X-ray spacecraft has found evidence for perhaps thousands of stellar mass black holes within 3 light years of Sgr A*. Astronomers found X-rays emanating from what appear to be over a dozen binary star systems that matched known signatures for other black hole systems. Because these were the brightest X-ray signals the researchers stated that there could be 300 to 1000 black hole systems whose X-ray signatures can’t be detected due to their distance from us. Based upon theoretical simulations of galactic dynamics there could be as many as 20,000 binary system stellar black holes that could drift inward to the galaxy’s center over billions of years. Additional follow-on theoretical work was announced at the same time that near Sgr A* there could be as many as 10,000 to 40,000 stellar mass black holes that do not have companions.

To us this would seem to be an astounding number of black holes, and in our daily experience these are large numbers. But in a galaxy with perhaps as many as 400 billion stars this is a small percentage. And when you figure in the masses of these black holes from roughly 5 to 30 solar masses they can add to the overall mass of Sgr A* if they end up merging with it.

Another group of astronomers is studying supermassive black hole mergers in galaxies. They found that a lot depends on the relative sizes to each other of the merging galaxies with the larger galaxy being dominant. Only a small percentage of the supermassive black holes initially end up at the center of the merger, with most from the small galaxy being flung out farther away and taking longer than the age of the universe to migrate to the center. Since we believe the Milky Way has had mergers in its past with at least dwarf galaxies, their computer simulations show that on average for a galaxy the size of the Milky Way, twelve additional supermassive black holes were added.

Andromeda has a supermassive black hole of its own, so when the merger begins in earnest with the Milky Way and Sgr A* things are going to happen.

Mergers in our galaxy probably happened early on in the first several billion years of its life and before the formation of spiral arms. Gaia data appears to indicate that in the last 9 billion years the Milky Way has not merged with any galaxy larger than the Large Magellanic Cloud (LMC). Well, we know that is going to change in 5 billion years. And oh, by the way, Gaia data shows that there is a supermassive black hole at the center of the LMC.

Most if not all individual galaxies usually are part of a small local group of galaxies that are gravitationally bound to one another, moving through space as a group. Such is the case for our Milky Way Galaxy which, along with the Andromeda Galaxy, are the two largest galaxies in our Local Group of galaxies. The Local Group has several dozen galaxies comprised of spirals and dwarf galaxies. Another spiral galaxy in the Local Group called the Triangulum Galaxy may be gravitationally aligned with the Andromeda Galaxy and may in fact merge with it one day.

Our Local Group is believed to be on the fringes and possibly part of a galactic cluster called the Virgo Cluster, with more than 1300 galaxies packed into a dense clump only 65 million light-years away. Astronomers used to think this was all part of a galactic supercluster of galaxies called the Virgo Supercluster of galaxies. But based on recent observations and analysis we now know that the Milky Way, the Local Group and the Virgo Cluster and the Virgo Supercluster are all part of a really big supercluster of galaxies called Laniakea – Hawaiian for “Immeasurable Heavens.” And all of this is being gravitationally attracted to a region of space called the “Great Attractor.”

A little over a decade ago astronomers discovered the cosmic web, which is thought to be the dark matter framework upon which galaxies made of both regular and dark matter reside. The cosmic web seems to resemble the neural network we see in the human brain – pathways of neurons and synapses that form a great but yet eloquent entanglement/network.

Our home galaxy is but one of two-plus trillion galaxies that exist in the observable universe. We may even discover far more galaxies as monster Earth-bound telescopes in the 30+ meter class come online and the James Webb Space Telescope launches and becomes operational. Let’s learn a few more specifics about our galaxy and then go about learning how to photograph this majestic spectacle in the sky at sea.

In 1926 Edwin Hubble classified galaxies as being either an elliptical, spiral or barred spiral. His classification scheme of galaxies was based upon his observations made with the 100-inch Hooker Telescope at Mount Wilson Observatory.

Elliptical galaxies can be very large and contain little gas or dust; there are no elliptical galaxies that we can see with our unaided eyes. The Triangulum Galaxy is classified as a spiral galaxy due to its grand spiral arms and smaller spurs that emanate from its center. The Milky Way is known as a barred spiral galaxy, as astronomers have been able to determine that a bar structure of stars stretches across the center of the Milky Way; we have seen other barred spiral galaxies, and they form a subset to the spiral galaxy classification.

In addition to the spiral arms, spiral galaxies contain a lot of gas and dust that align with these spiral arms and are, as we saw in the last chapter, the raw material for the formation of stars. In the next chapter we will discuss how solar systems and planets are formed from such raw material due to the birth of stars.

The Milky Way is estimated to be about 100,000 to 150,000 light years in diameter, and our Solar System is located out in the suburbs about 27,000 light years from the galactic center and Sgr A* – a good thing!. We can look in the direction of the center of the Milky Way, which is in the constellation Sagittarius, but we cannot see it due to the intervening gas and dust. During the summer months of the Northern Hemisphere and the winter months of the Southern Hemisphere is when the Milky Way is at its most grand during the early evening hours.

Looking up at a cloudless and moonless dark sky while at sea reveals the milky white boundary for which our galaxy was named. This delicate and beautiful boundary is composed of the light of countless faint stars. We also see the dark bands that are immense clouds of dust that block out the stars, especially the “Great Rift,” which dominates the view in the area of Cygnus and Aquila. The magnificent Scutum Star Cloud draws our eyes to it due to the stark contrast caused by the adjacent Great Rift. Always our eyes find their way to settle upon the grand majesty that is Sagittarius. It is here that one can mistake the view as being caused by passing clouds, as the constellation of Sagittarius the Archer holds so many celestial jewels for us to behold.

If you are lucky enough to get to the equator and even better, “down under”, besides the Milky Way you have three special viewing and astrophotography treats awaiting you – the Southern Cross and the Large and Small Magellanic Clouds – (LMC) and (SMC). The Milky Way runs through the Southern Cross, which has inspired songwriters, romantics and sailors through the ages. It is a sight not forgotten, but one has to make sure that they do not fall prey to the “False Cross,” which is far larger and to the west of the Southern Cross. An annotated photograph in Chap. 4 was included to show you the difference between the two. You know you have the right cross when you see the gatekeepers Alpha and Beta Centauri near the Southern Cross. The whole region is awash with stars, emission and dark nebulae including the famous Coalsack Nebula, which is next to the Southern Cross.

The LMC and SMC are dwarf galaxies that are gravitationally interacting with the Milky Way Galaxy. The LMC is about 179,000 light years distant and has about 10 billion solar masses, while the SMC is 210,000 light years away and has about 7 billion solar masses (Figs. 7.2 and 7.3).

Fig. 7.2

Black and white land-based astrophotograph of the LMC and the Tarantula Nebula taken using a five-minute exposure with an Internet-controlled robotic 4-inch refractor telescope and astronomical CCD. (Image by the author)

Fig. 7.3

Black and white land-based astrophotograph of the SMC taken using a five-minute exposure with an Internet-controlled robotic 4-inch refractor telescope and astronomical CCD. (Image by the author)

The LMC and SMC were known to Polynesian navigators, but it wasn’t until Captain Ferdinand Magellan (1480–1521) entered them in his log during his historic circumnavigation voyage – 1519–1522 – that they became known to the western world. As a result they bear his name. They can best be seen below the equator, and do appear like clouds. It isn’t until time exposures are taken that they become recognizable as dwarf galaxies. They are truly spectacular.

While we’re on the subject of galaxies we need to include the only other galaxy that is fairly easy to see and possible to photograph, although with some difficulty at sea, the Andromeda Galaxy. Yes, you could hunt down other galaxies with a possible chance of seeing them visually with your eyes and binoculars, but you probably will not be able to photograph them, as they are too faint. The Andromeda Galaxy, as you have learned, is heavily intertwined with the history of astronomy and the eventual fate of our galaxy. It is fairly easy to find using your software and can be seen with the unaided eye at sea. It holds the distinction of being the farthest thing you can see (reliably) with just your eyes at 2.5 million light years distant.

This is where the use of an optical aid in the form of binoculars is so very important. Scanning with binoculars, especially the Vixen 2.1x42, opens up the sweeping and awe-inspiring vista of our galaxy, the LMC, SMC and the Andromeda Galaxy in a way that our eyes alone can never do. Observing the heart of the Milky Way in Sagittarius and then the path to the left and/or right of it depending on your location is something you will want to do whenever you get the chance. The colors of the individual stars, the visual hints that are star clusters, emission and dust nebulae and the delicate background of stars will take your breath away. The clouds become a bit more real to us when we see them through binoculars and tease us with things we imagine that we see. The Andromeda Galaxy is a bit brighter and takes on a distinctive elongated shape when seen through binoculars. Might there be Adromedans looking back at us in the Milky Way?

These visual views will serve as your inspiration to want to photograph our galaxy and its accompanying LMC and SMC dwarf galaxies in all their glory, which you can do at sea. You may also want to push the photographic envelope at sea in photographing the Andromeda Galaxy – it can be done as you shall see.

Photographing the Milky Way

There is no greater astrophotography subject than our own Milky Way Galaxy. Its majesty, splendor and beauty are beyond compare to anything else in the sky. You really want to try and get some good astropics of this while at sea.

You have the best chance of getting that picture of a lifetime by using a DSLR with interchangeable lenses. It is possible to get a picture of the Milky Way with any camera that allows you to take time exposures of at least several seconds duration at an ISO of at least 3200 from a steady position. One picture on Twitter that the author says was of the Milky Way used an iPhone and the NightCAP Camera application, but tablets are not likely to work at all. Pocket cameras that have a real lens with ISO and exposure adjustments mounted on a tripod might work, but there is no evidence I could find that they do.

To get the best possible astrophotograph of the Milky Way several things have to happen that do not involve your camera setup. Your ship has to be in a location and time frame where the Milky Way is visible. This is where your software is an invaluable tool, although the planisphere and star charts can help as well but not as efficiently or easily. What you are trying to determine is when the Milky Way will be above the horizon and what part of it will be visible.

There are times and southerly latitude locations when the Milky Way will show the Sagittarius to Centaurus portion of the galaxy, while in the Northern Hemisphere summer will show the Sagittarius to Cygnus stretch of the Milky Way. You have to basically input the date and location of “where and when” to determine what the Milky Way will look like. You also have to remember that in the months leading up to “prime time” – that is, the convenient evening hours that the Milky Way is visible – it will be visible in the early morning hours before dawn.

Astro Tip

Once you have mastered the techniques for the Milky Way as a whole you may want to concentrate on specific areas such as the Southern Cross or the Northern Cross. The galaxy affords many interesting areas to zero in on. You may even want to try to take successive pics to make them into a panorama using software.

Below is an example of a table of visibility for the Milky Way from two at-sea locations from both hemispheres to give you an idea of how this works. The times are for when the galactic center of the Milky Way is at or as close as possible to the meridian, its highest point in the sky. Enter the location and date/time you are interested in to determine visibility by making a table like this. 

MILKY WAY GALACTIC CENTER VISIBILITY

Northern Hemisphere

LATITUDE :

36° 12′ 04.2″ N North Atlantic Ocean

LONGITUDE:

041° 02′ 45.5″ W

TIME ZONE:

GMT -1

April 1

0600

May 1

0500

June 1

0300

July 1

0100

Aug 1

2300

Sept 1

2145

Oct 1

2100

Galactic center is now in the SW

Nov 1

2100

Galactic center is now very low in the SW

MILKY WAY GALACTIC CENTER VISIBILITY

Southern Hemisphere

LATITUDE :

36° 12′ 04.2″ S TASMAN SEA

LONGITUDE:

160° 34′ 41.0″ E

TIME ZONE:

GMT +12.0

April 1

0600

May 1

0500

June 1

0300

July 1

0100

Aug 1

2300

Sept 1

2100

Oct 1

2100

Galactic center is now in the SW

Nov 1

2100

Galactic center is now very low in the SW

When you are ready to photograph the Milky Way it really pays to have a DSLR on a tripod, with either a cable release or shutter exposure delay. You are trying to capture very faint details and get as much exposure as possible – depending of course and always on what the sea will give you to work with in terms of wind and waves.

Try to find the darkest area on the ship that affords the best view of the Milky Way. If need be, act as a light block, using your body or your jacket. The easiest way to get a Milky Way pic is to use your widest angle lens available – and perhaps a fisheye lens – set wide open to infinity focus, ISO 3200 , on a tripod with cable release/exposure delay and try 10, 20 and 30 seconds if you have a 14 to 18 mm f/2.8 lens. If your lens is in the 20 + mm range go with 10, 20 and 25 seconds, as you have to watch the star trailing. Shoot, assess, adjust and shoot again. If the sea is steady and the wind calm you will get something!

A wide-angle view is very pleasing, but if you have good conditions with a steady sea and little wind go for broke with a 35- to 50-mm shot. Now, you really have to have a tripod to hold your camera steady. Use ISO 3200 , wide open lens set on infinity focus with cable release/exposure delay and try 2, 2.5, 3 and 5 seconds. Beyond that, with a 50 mm you will get star trailing. Shoot, assess, adjust and shoot again. These shots are tough to get unless the sea is very calm and the wind is almost zero, but if you do, oh boy, are they keepers!

Using a telephoto for Milky Way shots is not recommended, as any motion in the ocean, wind and the time necessary to get any detail will just result in a blur. But hey, nothing says you can’t experiment and see what you come up with.

Here are some of the author’s best Milky Way at-sea astrophotos to date (Figs. 7.4, 7.5, 7.6, and 7.7).

Fig. 7.4

Object viewed: Milky Way galactic center. (Image by the author)

Ship: Azamara Quest

Lens used: 50 mm f/1.4

ISO : 5000

Exposure: 4 seconds

Comment: Taken in the Coral Sea this exposure of 4 seconds was possible only because of very smooth sea conditions. The galactic center is above the bright star cloud

Fig. 7.5

Object viewed: Milky Way Antares region. (Image by the author)

Ship: Azamara Quest

Lens used: 50 mm f/1.4

ISO : 5000

Exposure: 3 seconds

Comment: Taken in the Coral Sea this exposure shows the dark nebulosity around the star Antares. It is shown in black and white, as the background sky was of poor white balance

Fig. 7.6

Objects viewed: Milky Way, Southern Cross. (Image by the author)

Ship: Azamara Quest

Lens used: 14 mm f/2.8

ISO: 5000

Exposure: 20 seconds

Comment: Taken in the Coral Sea this exposure shows a wide field containing the Milky Way, Southern Cross, and LMC. Some lens flaring is visible due to ship lighting

Fig. 7.7

Objects viewed: The Milky Way, Southern Cross. (Image by the author)

Ship: Azamara Quest

Lens used: 14 mm f/2.8

ISO : 5000

Exposure: 13 seconds

Comment: Taken off the coast of Sydney, Australia, this exposure shows a different perspective to a wide field containing the Milky Way, Southern Cross, and LMC. Light pollution is visible

You also want to make sure the Moon is out of the sky, as its brightness can easily overwhelm the Milky Way. A few days before or after the new Moon is best. However, the Moon can add to the panorama of the Milky Way; even a small scattering of clouds can be quite dramatic (Fig. 7.8).

Fig. 7.8

Objects viewed: Milky Way, Moon, Jupiter. (Image by the author)

Ship: Star Pride

Lens used: 14 mm f/2.8

ISO : 5000

Exposure: 10 seconds

Comment: A bit of EKG in this astrophoto but still worth seeing, as the Moon, clouds and Milky Way team up for a pretty sky scene

For the Southern Hemisphere we have also included an example of visibility listings for the Southern Cross and the Large and Small Magellanic Clouds (LMC) (SMC). You will want to make such listings for your particular location and date/time. The Southern Cross and the dwarf galaxies are must-see bucket list items. When the Southern Cross is on the meridian it marks due south, so that is the times that are given. For the LMC and SMC the time is for when each is closest to the meridian; the dwarf galaxies are not next to one another but separated by a few degrees, the LMC will be the larger of the two.

SOUTHERN CROSS VISIBILITY

Southern Hemisphere location example. You will want to make a table for your location and date.

LATITUDE :

36° 12′ 04.2″ S TASMAN SEA

LONGITUDE:

160° 34′ 41.0″ E

TIME ZONE:

GMT +12.0

April 1

0200

May 1

2300

June 1

2100

July 1

1930

Aug 1

2000

in the SW

Sep 1

2000

in the SW

Oct 1

2100

in the SW

Nov 1

2100

very low in the SW

Photographing the Southern Cross

The expertise you build up in taking pictures of the Milky Way will serve you well in photographing the Southern Cross, as all the techniques and settings are the same. In essence you are photographing the Milky Way and concentrating on a particular section of it (Fig. 7.9).

Fig. 7.9

Objects viewed: Alpha, Beta Centauri, Coalsack Dark Nebula, Southern Cross and Eta Carinae. (Image by the author)

Ship: Azamara Quest

Lens used: 50 mm f/1.4

ISO : 5000

Exposure: 3 seconds

Comment: Perfect sea and sky conditions in the Coral Sea allowed me to capture this incredible region of the Milky Way

LMC AND SMC VISIBILITY

Southern Hemisphere location example. You will want to make a table for your location and date.

LATITUDE :

36° 12′ 04.2″ S TASMAN SEA

LONGITUDE:

160° 34′ 41.0″ E

TIME ZONE:

GMT +12.0

April 1

0400

May 1

0200

June 1

0000 Midnight

July 1

2200

Aug 1

2000

Sept 1

0500

Oct 1

0400

Nov 1

0300

Photographing the LMC and SMC

The expertise you build up in taking pics of the Milky Way will serve you well in photographing these, as all the techniques and settings are essentially the same. However these are galaxies and not point sources like stars. As you can see they show up on wide-angle pics, but they are best photographed with a 35- or 50-mm f/1.4 lens to get as much light and detail as possible. The 50-mm pic of them turned out nicely, but once again sea conditions were perfect (Fig. 7.10).

Fig. 7.10

Objects viewed: LMC and SMC. (Image by the author)

Ship: Nautica

Lens used: 50 mm f/1.4

ISO : 5000

Exposure: 8 seconds

Comment: Lucky to be able push this exposure of the LMC and SMC to 8 seconds

Photographing the Andromeda Galaxy

Your setup will be the same as when you took your Milky Way pics. But the difference is going to be that you will have to point your camera as best you can in the general direction of the galaxy, as it is too dim to see in the viewfinder. Your ISO is going to have to be higher as well, as you are trying to pull photons in from 2.5 million light years away! You may be able to get the Andromeda Galaxy in a wide angle as an elongated object, but it will be very, very small!

Using a 35- or 50-mm f/1.4 will make it brighter and a bit larger. Sea conditions have to be perfect also, as you are dealing with an elongated object and not stars, so it will show trailing or ship motion very easily. As you can see from the pics below there is star trailing, but enough photons were caught to show Andromeda (Figs. 7.11 and 7.12).

Fig. 7.11

Object viewed: Andromeda Galaxy. (Image by the author)

Ship: Prinsendam

Lens used: 14 mm f/2.8

ISO: 5000

Exposure: 15 seconds

Comment: The Andromeda Galaxy is dead ahead, just above the eastern horizon

Fig. 7.12

Object viewed: Deep Exposure Andromeda Galaxy. (Image by the author)

Ship: Prinsendam

Lens used: 50 mm f/1.4

ISO : 5000

Exposure: 4 seconds

Comment: Taken right after the previous picture this is a DEEP B & W exposure (w/EKG present) of the Andromeda Galaxy, but it actually shows the elongated shape of the galaxy

As we leave the home galaxy and some of its neighbors behind to explore our Solar System you will almost definitely find yourself returning to the Milky Way every chance you get, on shore or at sea.

© Springer Nature Switzerland AG 2018

Gregory I. RedfernCruise Ship Astronomy and AstrophotographyThe Patrick Moore Practical Astronomy Serieshttps://doi.org/10.1007/978-3-030-00958-8_8

8. The Planets

Gregory I. Redfern1  

(1)

NASA JPL Solar System Ambassador, Ruckersville, VA, USA

Gregory I. Redfern

As of May 2018 there were almost 4000 confirmed planets beyond our Solar System with another 3000 candidates awaiting confirmation. These worlds beyond our Sun’s family of planets, comets and asteroids are called exoplanets. Everywhere we look in the Milky Way Galaxy we see stars that have planets in orbit around them.

Among other unusual planets we have detected Jupiter-sized exoplanets that orbit their star in Mercury-sized orbits. We have seen diminutive red dwarf stars hosting exoplanets, and the closest known exoplanet is only 4.24 light years away, orbiting a star called Proxima Centauri, which is gravitationally bound to Alpha and Beta Centauri.

You can’t see Proxima Centauri with your unaided eye, but you can see its general location when you look at Alpha and Beta Centauri, as it is below and to the right of Alpha Centauri, forming a triangle with Beta Centauri. In 2018 Proxima Centauri was observed to have undergone a significant outburst of deadly radiation, which is thought to have been sufficient to kill life as we know it. It may not be a good thing to be a life-supporting planet with a red dwarf star. Then, too, it may be a bad proposition to be a planet and have a very massive star as your home star, as it will go supernova someday, taking you with it.

Our study of stars and exoplanets has led to the idea that the formation of stars produces planets and solar systems as a direct byproduct. Astronomers are studying different theories as to how our Solar System and other stars and their exoplanets formed. This is a major area of study that has lots of exoplanet systems to observe and analyze. With new instruments and telescopes coming available in the near future in all likelihood we will see major advances in our understanding.

We discussed how stars are formed in Chap. 6, arising out of giant molecular clouds and nebulae. But as the star contracts into a protostar there is a lot of raw material left over that can cover over a light year in size. The remnant gas, dust and elements that make up the cloud can begin to gravitationally attract ever-increasing amounts of this matter into a proto-planetary disk that revolves around the developing protostar.

If enough matter accumulates it can begin to gravitationally attract more matter into an area that undergoes increasing density, which in turn increases the ability to gravitationally acquire even more material. Because the protostar is the gravitational center of this developing proto-planetary disk all of the material is in orbit around it.

Areas in the proto-planetary disk may be able to start solidifying and even aggregating into ever larger material – dust grains into pebbles into rocks into boulders into planetesimals. Eventually, over a period of time as much as a million or more years, these planetesimals in defined orbital zones undergo collisions and violent mergers – clearing out matter while adding mass to the developing planets. There could be wholesale rearranging of planets or some planets even being ejected from their parent star system.

Eventually the protostar begins the nuclear fusion that turns it into a star. After a period of time the star undergoes a turbulent transition from its birth to settle into its lifetime of producing energy, light and the chemical elements. The mass of the star obviously has a great effect on the developing planets around it. If it is a large mass star it will be putting out a lot more energy than a star the size of the Sun or a red dwarf star.

Close to the star molten-surface or vapor-filled planets might form, followed by solid rocky planets. The orbital zones farther removed from the star and its heat might be able to retain more of the gases and other volatile materials and surround a small solid core to become gas giants. The farthest planets might be frozen. Astronomers have seen all sorts of planetary systems, but so far no solar system quite like ours has been found. We have not yet have found Earth 2.0.

We have found what astronomers call “Super Earths,” which are about 1.5 to 2 times the mass of our planet. We have even discovered some planets that exist in what is called the “Goldie Locks Zone” – the area where if water were present on the planet it could exist in a liquid state due to being close enough to its star. With the monster telescopes being built and the James Webb Space Telescope coming on line in the near future we will be able to detect water vapor and other gases in the atmosphere of exoplanets. Think of what it might mean if we discover water vapor, methane, or maybe even “smog,” indicators of life on our own planet, on an Earth 2.0 orbiting a Sun-like star. Exoplanets are an exciting and growing area of planetary science and astronomy, as is the science of astrobiology.

We think our own Solar System underwent a process like this about 4.6 billion years ago, which we can deduce through our computer simulations, our numerous planetary spacecraft missions to all of the planets of the Sun and our study of rocks from Earth, Mars and the Moon. We are always learning more about our Solar System with each new meteorite that comes to Earth, comet discovery, planetary mission and exoplanet discovered. It is an exciting time to be a planetary scientist.

We can easily see and photograph five of the planets – Mercury, Venus, Mars, Jupiter and Saturn – the planets known to the ancients. But being at sea really makes it easier to do so than on land because we have the advantage of a clear horizon and full coverage of the sky. On land, buildings, trees and the terrain can get in the way of seeing the planets, especially the horizon-hugger Mercury – more on that in a bit.

If you have astronomical software (a planisphere or star charts are no help here unless you know what constellation the planets are in) you can see what planets are visible at a particular time by checking the “Tonight” option, which lists what planets and satellites are going to be visible for a specific location and date. But it is also helpful to check the monthly listing of the Observer’s Handbook or similar reference to get an idea of what is happening in the Solar System and the sky.

Doing so you get one-stop shopping that tells you all you need to know about the planets for the month as well as any close groupings between the planets and/or the Moon. That is hard to get from software. Software can give all kinds of sky and planetary particulars instantly, but unless you know about a close grouping in advance it won’t inform you about it until you see it displayed on the screen. So make sure you stay aware of sky happenings when it comes to the planets and also the Moon.

The planets, all of them, including Earth, are in perpetual motion in their orbits around the Sun. They change their position in the sky each day, and this changes their appearance in our sky. The planet that does this most dramatically is Mercury, which is where we will start our discussion on the planets.

Mercury

Mercury was named for the swift messenger of the Roman gods, as its rapid movement in the sky was well known. The planet closest to the Sun completes one orbit in just 88 days. Mercury is always close to the Sun, never more than 28 degrees away, which means that it is close to the western horizon at sunset and the eastern horizon at sunrise. Mercury can be rather bright, but it is always in twilight. Some apparitions of Mercury can be more favorable to one hemisphere over the other, which is the type of information you get from the Observer’s Handbook .

We have explored Mercury by spacecraft, and the European Space Agency is preparing to send its BepiColombo mission to the planet. NASA’s completed MESSENGER mission revealed much about the planet’s surface composition, including that Mercury has a larger iron core than Planet Earth does – one of the biggest surprises of the mission. Mercury also has features called “hollows” that have not been seen anywhere else in the Solar System . Hollows were observed to be shallow, irregular, rimless depressions that were found all over Mercury in impact craters. They appeared to be fresh features and might have been caused by volatiles that vaporized in the intense sunlight and high temperatures, leaving the hollow depression behind.

Visually Mercury is found lurking near where the Sun sets or rises. To many Mercury is a golden-yellow color, and once you recognize/identify it the planet is quite easy to see. The best way to find Mercury is that when it is near Venus, another planet or the Moon you can use these as guideposts to Mercury. Another way is to use the “compass or gyroscope” feature of your software installed on your smartphone and zero in on Mercury. Once you have seen Mercury it will help in finding and recognizing it again. It has been said that less than one percent of all the humans ever to live on Earth have seen Mercury and recognized it as a planet. When you see it the first time you will likely be surprised at how bright and visible it can be.

Mercury can get as bright as −2 and as dim as +5.5. Your software, Observer’s Handbook or other reference can tell you its brightness. The trick to photographing Mercury is to seek a balance between the brightness of the sky at sunset or before sunrise and the planet’s distance above the horizon. Because you are looking for the brightest possible image of Mercury to bring out its color and make it stand out in your photo you are probably going to shoot it close to the horizon, and we mean close, perhaps less than 10 degrees above it or lower.

Now you see why being at sea is such an advantage, because we can theoretically photograph any astronomical object almost right at the horizon. The longer you wait for the sky to get dark the brighter and lower in the sky Mercury will be. The condition of the horizon and the atmosphere will of course impact your shooting setup. If the horizon is lousy with clouds, fog or thick haze you may have to get your photo higher and dimmer. Or, you may go with a longer exposure in the horizon muck to try and bring Mercury out.

You might be able to photograph Mercury with a hand held camera, but if you have to do a 1- to 2-second exposure you cannot hold the camera steady. If Mercury is bright enough you might even be able to bag it with a smartphone and pocket camera. As always the DSLR gives you your best chance.

Because Mercury will be in a fairly bright sky your ISO will not have to be very high, perhaps 200 to 400 depending on how clear the horizon is and how low Mercury will be when you get your pic. A wide-angle lens would not be a great choice, as the image would be small and quite possibly lost in the dusk or dawn sky. A 50-mm or better yet a zoom lens would be best, as you can get good image size and quality to pull Mercury out of the background light. Have the lens wide open, as the light and the shutter speed will have to be determined by trial and error. You can play with a higher ISO to reduce the shutter speed, but you know by now to: shoot, assess, adjust, shoot (SAAS). In fact, from here on out that is how we will refer to this process.

A tripod would be of great help here, but if one is not available you might be able to use the ship’s deck rail to put your camera on for the shot. Mercury will be fairly close to the horizon, and the deck rail would be sturdy and afford a good view of the horizon.

If Mercury is bright enough and your horizon is good, try to take a pic with both in the frame. This can produce a dramatic view, with the colors of sunset accenting the horizon and Mercury a lone “star.” If circumstances permit, a variation of this is to photograph it bright and low to the horizon, with Mercury’s light reflected in the water. That would be a keepsake picture. In Fig. 8.1 both Venus and Mercury, along with the Milky Way (!), are all in one frame (Fig. 8.2).

Fig. 8.1

Objects viewed: Mercury with Venus at sunset. (Image by the author)

Ship: Azamara Quest

Lens used: 55–200 mm at 56 mm f/4.5

ISO : 2000

Exposure: 1/13 second

Comment: Mercury is higher and dimmer than Venus in this sunset picture off the coast of Cuba

Fig. 8.2

Objects viewed: Mercury, Venus and the Milky Way. (Image by the author)

Ship: Azamara Quest

Lens used: 14 mm f/2.8

ISO: 6400

Exposure: 10 seconds

Comment: In the Tasman Sea a nice sight before sunrise. High ISO to bring out Venus’s refection in the water and the Milky Way

Venus

The next planet is the brightest of them all and captures our attention whenever it is in the morning or evening sky. Venus, the goddess of love and beauty to the Romans, is certainly beautiful and inspiring in a dark sky. Venus can be seen in a dark sky, as it can be farther from the Sun than Mercury but similarly always remains in the sky in the hours before sunrise or after sunset. Venus is also known as the “Morning Star” or “Evening Star,” which of course are misnomers, but these nicknames have stuck with the planet regardless.

Venus can be as bright as a dazzling −3.8 to −4.4 and can actually cast your shadow on the ground if you are in a really dark location and have a light-colored ground cover. It is brighter than any star in the sky and is the third brightest object in the sky following the Sun and the Moon. Venus is so bright it can be seen during daylight hours if one knows where to look.

Venus was found to be an almost identical twin to Earth in terms of size and mass. By observing Venus in telescopes it was found to be cloud-covered with carbon dioxide being one of the components in the clouds. Venus was envisioned as a world where it could be a very wet and warm swampland or a very dry world of deserts.

Venus was also found to rotate very slowly on its axis, taking 243 Earth days for one rotation! It also rotates in retrograde (opposite) the direction of its orbit around the Sun. Venus was found to be even more inhospitable – hell-like actually – when America and the Soviet Union (USSR) sent spacecraft to land on the surface. Sulfuric acid rained from the clouds, and the temperature was hot enough to melt lead; add to that a surface pressure that is equal to 92 times that of the Earth, and you have an environment that destroys spacecraft.

Venus was found to have volcanoes, lava flows and impact craters. It has a weak magnetic field due to the slow rotation rate and no plate tectonics. It remains of interest due to the runaway “Greenhouse effect” caused by the dominating carbon dioxide in the planet’s atmosphere.

Venus is a piece of cake to find and photograph compared to Mercury. It is brighter, higher in the sky and most importantly can be photographed in dark skies. Your setup is the same as with Mercury, but you need a higher ISO if Venus is in dark skies, maybe ISO 800 to 1000. If you are trying to photograph the star field around Venus you can increase the ISO and exposure time. Try to use a medium lens – 35-mm to 50-mm – wide open for the star field shots and exposure 1–2 seconds, SAAS (Figs. 8.3 and 8.4).

Fig. 8.3

Object viewed: Venus. (Image by the author)

Ship: Nautica

Lens used: 14 mm f/2.8

ISO : 5000

Exposure: 2 seconds

Comment: Christmas Eve sunrise and Venus is dead ahead

Fig. 8.4

Objects viewed: Venus and the Milky Way. (Image by the author)

Ship: Azamara Quest

Lens used: 14 mm f/2.8

ISO: 5000

Exposure: 15 seconds

Comment: In the Tasman Sea, a nice sight before sunrise. High ISO to bring out Venus’s refection in the water and Milky Way. The ship’s deck lighting brings out the color of the water

Be alert to when the waxing/waning crescent Moon (see Chap. 9) will be in proximity to Venus. There are few sky scenes that can compete with a brilliant Venus near an Earthshine-drenched Moon. It is a bit of a challenge to get the right exposure to bring out the Earthshine, as it is subtle. You can look at a higher ISO to help out, but your exposure time will be at least 2–3 seconds; beyond that you will probably experience trailing of your image. A zoom lens is a big help here, as you can frame the shot to get a pleasing result with detail on the Moon (Fig. 8.5).

Fig. 8.5

Objects viewed: Venus and Moon. (Image by the author)

Ship: Oosterdam

Lens used: 28–300 mm at 82 mm f/5

ISO : 3200

Exposure: 1.6 seconds

Comment: Sunset shot in the Pacific of Venus and a young crescent Moon with Earthshine. The reflection of Venus in the water can’t be captured, as the exposure necessary would overwhelm the Earthshine

Mars

With Mars, the Roman god of war, you have a planet that only comes to prominence in the sky once every two-plus years. That is when Mars and Earth pass closest to one another. Mars can literally go from a dim 1.7 magnitude to a possible −2.9, which means it is brighter than Jupiter and the fourth brightest object in the sky after the Sun, Moon and Venus. It is something to see and photograph. Mars can get quite prominent with its color and brightness. The reddish-orange is striking and makes it easy to see why the Romans thought war was ravaging this wanderer in the sky.

Mars has frozen water below its surface and its polar caps. It once had liquid running water in lakes, rivers and perhaps even oceans when it was warmer, billions of years ago. Mars has no protective magnetic field, so its atmosphere is being literally blasted by the Sun. It is a place that has volcanoes – the largest in the Solar System – craters and complex weather complete with wind, clouds and widely varying temperatures. Harsh and yet most similar to Earth in the Solar System, Mars is currently being studied by NASA, ESA, India and perhaps soon commercial companies. Mars is the place where most experts think human colonization can take place on a large scale. Only time will tell.

Your setup for photographing Mars will be the same as the other planets, but Mars is the first planet we have discussed that can be visible any time of night. Its great variation in brightness can be a challenge to capture; when it is least bright, you will have compensate with a higher ISO of 1000 and longer exposure time of 1–2 seconds. Mars will easily cast its light on the water at its brightest, which would be an interesting photograph to capture due to its striking color. Mars at its brightest as it is rising above the horizon would also be a shot worth trying to get. I finally got a shot like this (Fig. 8.6). Also be alert to Mars being near the Moon or other planets. You would want a 35- to 50-mm wide-open lens to get these pics.

Fig. 8.6

Objects viewed: Bright Mars. (Image by the author)Ship: Star LegendLens used: 14 mm at f/3.5ISO: 3200Exposure: 13 secondsComment: Bright Mars rising and reflected in the Pacific Ocean

Jupiter

The Asteroid Belt will be discussed in Chap. 12, so mighty Jupiter is up next. The ancients associated Zeus, the great Greek god, with Jupiter. A mighty god that rules over all seems an apt description of Jupiter as a planet. Jupiter is usually the fourth brightest object in the sky, though Mars supersedes it occasionally. It is bright and can be viewed and photographed easily. Jupiter is the most massive planet in the Solar System, 11 times larger than Earth, and is the first of the gas giants as we leave the inner planets with their solid surfaces behind. The gas giant planets Jupiter and Saturn are composed mainly of hydrogen, helium and have metallic hydrogen far beneath the clouds that surrounds a solid core. Most of the mass of Uranus and Neptune is a hot, dense fluid of “icy” materials – water, methane and ammonia – above a small rocky core; they are ice giant planets.

If Jupiter were 10 times more massive it would be able to sustain nuclear fusion and become a small star. It is still radiating heat into space that is left over from its gravitational contraction and in this sense is a “failed star.’ Jupiter is a very complex planet, with dynamic weather systems in the clouds that form three decks and are composed of various elements and compounds that give the clouds distinctive colors that can be seen in amateur telescopes.

Jupiter has a thin ring system and at least 67 moons, four of which are far larger than the rest – worlds of their own, really. They were discovered by Galileo with his telescope in 1610 and are called the “Galilean Moons” in his honor. Each is distinct and has its own geology and characteristics. The four can be seen in 7x50 binoculars and observed to change their positions over a short period of time. In amateur-sized telescopes Jupiter offers the most detail of all the planets, with its equatorial belts (well defined zones of clouds), variety of colors, moons and its quick rotation of only 9 hours and 56 minutes . This fast rotation causes the poles of Jupiter to be noticeably flattened. The ring of Jupiter cannot be seen in amateur telescopes.

Your photograph setup will be the same as for the other planets, and like Mars, Jupiter can be visible any time of night. It can have a little variation in brightness but won’t be a challenge to photograph. An ISO of 800 and an exposure time of 1 second should be a good starting point. Jupiter should cast its light on the water, which would be an interesting photograph to capture. Jupiter rising above the horizon would also be a shot worth trying to get. Also be alert to Jupiter being near the Moon or other planets. You would want a 35- to 50-mm wide-open lens to get these pics. You MIGHT be able to capture the four main moons of Jupiter with a 200- to 300-mm telephoto lens, but the issue is ship’s motion and wind , as you would need at least a 1–2 second exposure at a high ISO. It is quite difficult to get steady enough conditions at sea.

Saturn

Saturn was named for the Roman god of the same name and is where “Saturday” got its name. Saturn was the last of the five visible planets and was the slowest moving, so it has been associated with the old and aged.

If you have ever looked at Saturn through a telescope you have experienced the grandest visual spectacle of the Solar System – its rings. They can be easily seen with amateur telescopes but not with binoculars. Galileo observed the odd appearance of Saturn in his telescope and drew small lobes on both sides of the planet. Christopher Huygens discovered the rings in 1665. Saturn displays similar features in its clouds as Jupiter, but the colors are blander and not as distinct due to the greater distance of the planet. The rings are mostly made of particles of water-ice, which is why they are so bright and mostly white. These particles can be pebble sized up to house-sized boulders, and their origin is not precisely known. The rings are spectacularly complex, with many ringlets, divisions and gaps. Small moons roam some of these gaps and have caused observed warping in the rings.

An interesting and recent possible theory about Saturn is that it can rain 1000 tons of diamonds from the atmosphere each year! This is due to the methane in the clouds being struck by the copious amounts of lightning , which turns it into carbon soot. As this falls deeper and deeper into Saturn’s atmosphere it becomes graphite and then diamond!

Saturn has at least 62 moons, with the largest being the cloud-covered Titan, the clouds made up of hydrocarbons in liquid and gaseous form. Titan is the only moon in the Solar System that has an atmosphere.

Your photograph setup will be the same as the other planets, and Saturn can be visible any time of night. It can have a little variation in brightness and can be a challenge to photograph. An ISO of 1000 and an exposure time of 1 second should be a good starting point. Saturn will probably not be bright enough to cast its light on the water, but maybe you might want to try if viewing conditions allow. Also be alert to Saturn being near the Moon or other planets. You would want a 35- to 50-mm wide open lens to get these pics. The rings are beyond photographing at sea, as you really need a telescope to do so.

Uranus

Uranus was the first planet to be discovered using a telescope and has been the victim of countless jokes over its pronunciations ever since, it seems. Uranus is bright enough to be seen with the unaided eye but was never referred to as a planet until William Herschel did so in 1781. Herschel referred to the new planet as Georgium Sidus (George’s Star), a clear reference to England’s King George III, but the rest of the world would have nothing of it. The dispute over the planet’s name continued into the next century, until it was finally decided in 1850 that Uranus, the Greek god of the sky, would be the planet’s name.

Trying to see Uranus with the unaided eye makes it easy to see how it evaded detection as a planet for so long. A dim 5.6 to 5.9 magnitude, the planet is nearly 2 billion miles from Earth, and it takes a very dark sky to see it. Uranus is the third largest planet in the Solar System, just edging out Neptune. It is a weird planet in that its rotational axis is almost horizontal to the plane of its orbit, while its equator is almost vertical. It is as though the planet got knocked over like a bowling pin. This makes for a magnetic field that has a 60-degree tilt from the axis of rotation and is offset from the planet’s center by a third of the planet’s radius. Simply put there is nothing else like this in the whole known Solar System.

Uranus was discovered to have a small and dim ring system in 1977 following Earth-based telescopic observations. The planet’s clouds are made of methane, and it is very cold at Uranus −360 degrees F; it has no internal heat source, like Jupiter and Saturn. Uranus has 27 known moons.

For photography, using your software to zero in on Uranus is an almost absolute necessity. Using the planisphere will not help, and star charts would be tedious to translate coordinates. Using the software you could narrow Uranus down to the constellation it is in and the stars it would be near. If it was near a bright star or other planet this would help a lot. But if you are trying to shoot Uranus by itself get a rough idea of where it is in the sky and point your camera in that direction/star field. Take your shot, and then use the computer view of your picture (large screen) to compare it to the star field and location of Uranus in your software. Using a split screen to view both simultaneously would help.

This author has photographed Uranus from land using a DSLR and a 50-mm lens when it was at opposition, or directly opposite the Sun; the pic was published by EarthSky.​org. It was difficult to see with the unaided eye but stood out pretty well in the photograph. I have also photographed it at sea when it was part of a three-planet line up of Venus and Mars that was visible on the bow of Westerdam . The ship was very steady, so with my tripod and cable release I could get an exposure of 1 second to capture the alignment. If you want to try and photograph Uranus try the settings used here, and, as always, SAAS (Fig. 8.7).

Fig. 8.7

Objects viewed: Uranus, Venus and Mars. (Image by the author)

Ship: Westerdam

Lens used: 28–300 mm at 28 mm f/5.6

ISO : 10,000

Exposure: 1 second

Comment: Sunset shot in the Pacific

Neptune

Neptune is the planet for seagoing cruisers, as it is named for the Roman sea god Neptune. Like Uranus Neptune was discovered using a telescope but with a difference. Once Uranus was discovered and observations were made of its orbit it was determined that some unknown body was gravitationally affecting it. Calculations were made by English astronomer John Couch Adams and French mathematician Urbain Joseph Le Verrier as to where to look for the unseen body, which they thought was a planet. Le Verrier sent their predicted coordinates to German astronomer Johann Gottfried Galle at the Berlin Observatory, who found Neptune the first night of searching in 1846. History records that Galileo observed Neptune when he was also observing Jupiter in 1612 and 1613, but according to his notes he thought it was a fixed star.

This was a pretty amazing feat, to find a planet using Newton’s laws of gravitation. As we shall see with Pluto this happened again in the search for an unseen body or planet.

Neptune is nearly 3 billion miles from the Sun and is a faint 8th magnitude, so it is beyond seeing with the unaided eye. If you knew where to look and were familiar with the star field you might be able to see it with binoculars – once again this is where software pays dividends.

Neptune is bluish in color and is known for having the strongest winds in the Solar System – 1200 miles per hour! It has had several very large dark spots and clouds in its atmosphere. Neptune has a ring system, but it is faint, and has 13 known moons.

For photographing Neptune you will have to use your software to zero in on it – an absolute necessity. You can’t see it without an optical aid. Using the planisphere will not help, and star charts would be even more tedious for translating coordinates for Uranus. Using the software you could narrow Neptune down to the constellation it was in and the stars it would be near. If it is near a bright star or other planet, that would help a lot. But if you are trying to shoot Neptune by itself, get a rough idea of where it is in the sky and point your camera in that direction/star field. Take your shot and then use the computer view of your picture (large screen) to compare it to the star field and location of Neptune in your software – using a split screen to view both simultaneously would help. Be aware that Neptune will be dim at 8th magnitude and tough to spot. If it is in the Milky Way, good luck finding it.

You will need really good conditions for taking your shot, such as a stable ship, no bright Moon and a fairly open star field. A tripod, cable release, ISO 2000 , a 50 mm f/1.4 and 1–2 seconds would be a good start, with SAAS a must. You might even have to shoot a couple of pictures and then go below to check on your computer if you even got it.

Better yet, wait a few days and shoot the area of the sky where Neptune is and you may be able to see its movement against the background stars,

Pluto

The controversy still rages as to whether Pluto is the ninth planet of the Solar System or not. Pluto was a planet until the International Astronomical Union in 2006 changed the definition of what a planet is following a very controversial vote of less than 500 astronomers out of a body of over 10,000. The vote came at the end of a conference, and the new definition did not have input from a lot of planetary scientists. Personalities and reputations became involved, and it almost became a big joke with appearances on late-night TV and books and Twitter names associated with the whole affair.

Pluto was found in February 1930 by American astronomer Clyde Tombaugh (1934–1997) after he compared some photographic plates he had taken the month before. Clyde used the 13-inch photographic telescope at Lowell Observatory to take plates of the sky several nights apart and then compare them to each other with a blink comparator. This was tedious work, which Clyde was well suited for.

Pluto was so named after a contest was held in which 11-year-old British school girl Venetia Burney (1918–2009) suggested the Roman god of the underworld. At almost 4 billion miles from the Sun this seemed an appropriate name.

Pluto was found to have a large moon in 1978, and it was named Charon. Pluto and Charon are classified as a double-planet system in that the moon is large in comparison to its parent planet. Earth and its Moon are the only other so-called double-planet system in the Solar System. There are a total of five known moons in the Plutonian system.

The New Horizons spacecraft flyby of Pluto in July 2015 completed humanity’s first reconnaissance by spacecraft of all nine of the classic planets in the Solar System . To many the best was indeed saved for last, as Pluto is perhaps the most incredible “planet” in the Solar System. Mountains made of water-ice taller than the Rockies, a multi-layered atmosphere, glaciers made of nitrogen, an impact-free feature with ripples and dark fissures, a moon with a dark pole spot – the list goes on and on. Check out the Appendix in this book for you to explore this wonderful planet.

Pluto is really difficult to photograph on land, let alone at sea. At magnitude 13 it is beyond the capability of anything you could deploy on a cruise ship. Save this one for onshore!

A far easier and beautiful world to photograph at sea awaits you in our next chapter, guaranteed!

© Springer Nature Switzerland AG 2018

Gregory I. RedfernCruise Ship Astronomy and AstrophotographyThe Patrick Moore Practical Astronomy Serieshttps://doi.org/10.1007/978-3-030-00958-8_9

9. The Moon

Gregory I. Redfern1  

(1)

NASA JPL Solar System Ambassador , Ruckersville, VA, USA

Gregory I. Redfern

Are you a lunatic? In the astronomical, not psychiatric sense? Like this author, have you been a Moon lover for as long as you can remember? Have the days of Apollo and observing and photographing the Moon cemented your relationship with Luna, Selene and all the names humanity has called our nearest celestial body? The Moon and Earth comprise a kind of double-planet system, as indicated in Chap. 8. As you will see we really are almost symbiotic with the Moon.

The Moon is second only to the Sun in brightness, and like the Sun, is of great importance to humanity. Our ancestors used the light of the Moon at night to hunt, gather crops and seek safety from the dark. The Moon affects the oceans and seas with its gravity to produce tides, which must be accounted for by ships when entering and leaving ports. Some scientists think that the ancient Moon might have helped life form on Earth, due to the far stronger tides billions of years ago that would have ravaged the shores and stirred up sediments and compounds in tidal pools. The Moon has helped to protect Earth from impacts due to comets and asteroids, taking some hits instead of Mother Earth. And the Moon has become a place to go to as the spacefaring nations of the world and private enterprises seek to return to the Moon and stay this time.

Origin of the Moon

Although we know a lot about the Moon, due to centuries of telescopic observations, spacecraft missions, lunar meteorites and the Apollo landings, there is a lot we still don’t know. Perhaps the biggest question is where the Moon came from. There has been an evolution of our theories about the Moon’s origin, with the current thought being that the Moon arose due to an impact with a Mars-sized planet called Theia about 4.4 billion years ago. This impact, according to the latest research, would have been head on and badly disrupted the fully formed Earth and according to some the oceans that were present as well. Earth’s crust would have been totally disrupted and Theia totally destroyed.

The impact may have also caused Earth’s 23.5 degree tilt, which is why we have our seasons. Molten and vaporized materials from Earth and Theia were thrown into space, possibly forming a synestia – a doughnut-shaped cloud of debris according to a recent theory – surrounding Earth. Over a period of time this material would have solidified into a ring around Earth composed of pebbles and boulders, which would aggregate into ever larger bodies.

Eventually there would have formed a large body or bodies. Some scientists think there could have been multiple moons orbiting Earth that eventually combined into one Moon due to collisions. Other scientists think there could have been other impacts on Earth to form other moons over the early billions of years. One point is clear, the Moon and Earth share a common origin; this is based on very sensitive testing of the Apollo samples and lunar meteorites . The only way this could happen would be if the Moon and Earth arose from a common origin – such as from Theia and Earth co-mingling their contents due to an impact.

What a sight it would have been to see the newly solidified Moon with a totally molten lunar surface only 40,000 miles from the also molten Earth. It would have dominated our skies, and Earth’s rotation could have been a speedy 6 hours or so a day! The Moon and Earth affect one another, as the ocean tides caused by the Moon (and to a lesser extent the Sun) act to slow Earth’s rotation which is why we have periodic leap seconds. The Moon’s orbital distance from Earth increases a little over an inch a year as a result of Earth’s tides.

When we look at the Moon we see two primary colors – white and gray. The white is the Moon’s original crust that, when it was forming, was molten and rose to the surface of the Moon due to it being primarily composed of the light mineral anorthosite. When the Late Heavy Bombardment of the Solar System took place about 4 billion years ago huge impact basins were formed as the result of impacts of asteroids and comets. The largest impact basin on the Moon is the South Pole-Aitken basin, which is 15-km deep and 2,600 km wide. It is one of the largest impact basins in the whole Solar System.

These impact basins were filled due to lava flows between 4.2 and 1.2 billion years ago. We see the boundaries of these impact basins by the “mountains” that surround them, which are really the impact basin walls. We can also follow their origins by the impact debris scars that some of them created when formed. The Mare Imbrium basin is one such example.

These lava filled impact basins are the gray-colored circular features we see on the Moon – the maria – that form the “Man or Woman in the Moon” that some people see at full Moon.

Visiting the Moon

The Moon had a critical part in the Cold War between communism and democracy, as space was the new frontier, and the Soviets held the high ground initially with unmanned and manned firsts. The former U.S.S.R (Soviets) photographed the far side of the Moon in October 1959 with Luna 3 and did the first landing ever on the Moon in February 1966 with Luna 9. The United States sent the Ranger, Lunar Orbiter and Surveyor spacecraft series to the Moon in preparation for the manned Apollo landings, which took place from 1969 to 1972. The Americans had won the race to land a man on the Moon, and the Soviets gave up trying. They did the last lunar landing for decades with Luna 24 in 1976. After that mission the Moon would become a “has been” for decades, as the belief was “we’ve been there and done that” and know all we need to know about the Moon.

It wasn’t until the 1990’s that humans started sending unmanned spacecraft to the Moon again. The United States even started talking about sending humans back to the Moon with the Constellation program in 2004. This program was subsequently canceled, but some aspects of it survived. Several lunar missions were designed and launched to learn more about the Moon in preparation for humans going back.

Two 1990’s U. S. missions, Clementine and Lunar Prospector, detected evidence that water-ice may exist on the Moon at the poles, due to data they collected. In July 2009 NASA launched two lunar missions, called Lunar Reconnaissance Orbiter (LRO) and Lunar Crater Remote Observation Sensing Satellite (LCROSS), using one rocket. LRO was a big spacecraft that was built at NASA’s Goddard Spaceflight Center, Greenbelt, Maryland. It was packed with instruments and cameras designed for long-term study and mapping of the Moon. LCROSS was small and designed to fly through and analyze an ejecta plume caused by the impact of the booster that sent LRO and LCROSS to the Moon.

Once LRO was in lunar orbit and functioning and the rocket booster devoid of any volatiles after being a long time in space, the booster impacted Cabeus Crater at the South Pole of the Moon. All eyes and telescopes on Earth and in space watched for any sign of an ejecta plume to rise above the lunar surface, but unfortunately it was not observed. The booster impacted Cabeus and LCROSS flew through the plume, returning data before it, too, hit the lunar surface.

The results from LCROSS confirmed the presence of water in the ejecta plume. In fact, the data indicated that perhaps Cabeus had as much as a billion gallons of water in the form of water ice – equivalent to 1500 Olympic swimming pools.

LRO has confirmed the evidence for the presence of water in the permanently shadowed regions (PSRs), craters on the Moon that have never seen the Sun illuminate their depths in the billions of years since the Moon’s formation. These are extremely cold regions, not far from absolute zero in temperature, and it is thought that any volatiles and water – deposited by volcanism or impact – would still exist in them, probably intermixed with the lunar regolith.

One other source of lunar water – magmatic water – was discovered in 2013 as a result of India’s 2008 Chandrayaan-1 mission on which NASA flew its Moon Mineralogy Mapper (M3) instrument. This water was chemically bound to the lava rocks of the Moon and was found to be quite prevalent. The presence of water on the Moon was a huge discovery that has equally huge implications for humanity, which we will discuss shortly.

NASA’s Lunar Atmosphere and Dust Environment Explorer (LADEE) mission was launched from NASA’s Wallops Island Launch Facility on September 7, 2013. Using a converted intercontinental ballistic missile (ICBM) – a U. S. Air Force Peacekeeper – the converted ICBM Minotaur V blasted off the launch pad at night, leaving behind scared frogs, lizards and other residents of the Wallops wildlife refuge. Humans cheered and clapped as the mission to the Moon swept northeastward with perfect staging and lighting up the eastern seaboard with its majestic plume; millions saw it.

LADEE was designed to solve a mystery from the Apollo missions, namely what were the streamers of light on the horizon before and after sunrise and sunset that some of the astronauts saw and drew? Some of these streamers were even photographed by the Surveyor 7 spacecraft. Scientists at the time were baffled and did not know what was behind this verified lunar phenomenon.

LADEE recorded over 17,000 dust impacts during its mission and discovered that the Moon had a permanent and lopsided debris cloud. LADEE also detected the presence of an exosphere – a primitive and weak atmosphere around the Moon that was composed of argon, helium and neon. These elements reacted to the position of the Sun in the lunar sky, the lunar day.

Lunar scientists made another big discovery about the Moon’s atmosphere in October 2017, when it was announced that the Moon had an atmosphere 2% that of Mars 3 to 4 billion years ago. This atmosphere was possibly due to lunar volcanism and lasted 70 million years. Lunar scientists also believe that the Moon’s “horizon glow,” seen by some of the Apollo astronauts and in images taken by Surveyor craft five decades ago, may have been caused in part by sunlight scattering in a cloud of electrostatically lofted dust particles.

NASA’s Gravity Recovery and Interior Laboratory (GRAIL) mission flew two identical spacecraft at a specified distance from one another in tight formation and at a specific altitude above the Moon. As a result, any changes to their flight path would be caused by changes in the gravity of the lunar environment. Concentrations of mass in an area and subsurface structures would be the causes of any flight path deviations. GRAIL found that Oceanus Procellarum, which had been previously thought to be an impact basin, was in fact a subsurface volcanic structure – a huge discovery.

As of May 2018 LRO is the only active lunar mission, but that could possibly change by the end of the year. China launched Queqiao, a small lunar communications satellite, in May 2018 that will orbit the L2 Earth-Moon Lagrange point in order to communicate with China’s planned Chang’e 4 mission, which is scheduled to land on the far side of the Moon at Von Kármán Crater, inside the South Pole-Aitken (SPA) Basin, and deploy a rover at the end of 2018.

China’s Chang’e 5 mission in 2019 is to land at Mons Rumker, a near side area of known past volcano activity and very probably the site of ancient lunar volcanic deposits. The lander will deploy a drill to retrieve 2 kg of lunar subsurface soil for return to Earth via a return sample capsule. This is a highly ambitious series of missions, but the technology was proven in China’s Chang’e 3 mission, which landed and deployed the Yutu rover and the Chang’e 5 TI mission that orbited the Moon and returned a capsule to Earth from lunar orbit.

In addition to China, India, Japan, Russia, Europe, South and North Korea as well as the United States have announced plans for lunar missions in the near future. Another dimension to lunar exploration is taking shape in the form of private companies that say they will be sending robotic missions to the Moon. In fact, NASA announced in early 2018 that it would be going back to the Moon with robotic and crewed missions in the coming years. NASA said in 2018 that it would buy commercial lunar robotic landers through its Commercial Lunar Payload Services (CLPS) program to deploy instruments and conduct lunar science.

NASA’s also stated its intention of going back to the Moon with future robotic and crewed missions and backed this up with the announcement of a new 2018 lunar initiative called the Lunar Orbital Platform-Gateway. This “gateway” would be a small space station in lunar orbit that could be visited by crews for 30 to 60 days at a time and could conduct experiments and science. Robotic landers could go to and from the Moon, and robotic operations could be conducted when crews were not present. This initiative was funded for the 2019 fiscal year as well as outlying years – something that did not always happen when NASA was talking about going back to the Moon. Most importantly it also appears to have bi-partisan congressional support – an ultra-rare occurrence these days.

One other aspect to this project that is historic in the history of spaceflight – there is an actual provision to make it part of a lunar refueling infrastructure. A serious look is being made at the water on the Moon as being a means to make rocket fuel – liquid oxygen and liquid hydrogen. This would be an iconic achievement, making rocket fuel from lunar resources that could be used on the Moon as well as the gateway to refuel spacecraft and landers.

Think of it. We could refuel spacecraft headed to/from the Moon, Mars and the outer Solar System. We could export that technology to the Asteroid Belt, which you will learn has the potential for lots of water. It would be a humanity-transforming event, making space travel accessible, sustainable and economically feasible on a scale never seen before. The Solar System could become as the sea lanes of the nineteenth and twentieth centuries, when steam replaced sail on ships and the ocean-based economy was in full bloom as a result.

The United States, Russia, Japan, Europe and China have all announced their intentions to send humans to the Moon in the coming decades. The Moon has resources to build lunar outposts, then colonies and then a full blown settlement. The potential nuclear fusion reactor fuel helium-3 is possibly even bigger than water or any other resource on the Moon.

This potential fuel has been deposited in the lunar regolith for over 4 billion years as a natural byproduct of nuclear fusion reactions that power the Sun. It has the potential to revolutionize energy production if a helium-3 nuclear fusion reactor can be built. Nations are working on this possibility, and the Moon is the source for fueling these reactors. There would be hardly any radioactive waste, they are super-efficient (just like stars are) and could power cities of millions each year with a few hundred kg of helium-3. This would be another humanity transformer.

Nations that invest in a permanent human presence on the Moon will be the first to reap the benefits from such an effort. The building of an economy using lunar resources – think lunar water, rocket fuel, helium-3, solar power beamed to Earth via microwaves, rare earth elements – will be a space age version of when Spain exploited the riches of the New World with its ships and colonies. China may lead the world in this lunar endeavor, because it has the political will and financial resources to do so. Only time will tell if the Moon – sometimes referred to as the “Fifth Continent” – becomes the New World of the twenty-first century.

Viewing the Moon at Sea

The Moon at sea is a wonder to behold. It goes through its main phases of new, first quarter, full and last quarter each lunar month of 29.5 days. You can photograph the Moon as it goes through its phases. The Moon photographs well during lunar eclipses, but we will cover that in Chap. 10.

Your software will tell you the Moon’s phase, the Moon’s location in the sky, as well as when the Moon rises and sets, all of which is very important information. Your planisphere and star charts are of no value in providing information about these details. The Moon also will move approximately 12 degrees from night to night, moving west to east in the sky. The ship’s information channel or daily bulletin may have Moon information as well.

It will also appear higher and lower in the night sky depending on the time of year. As a rule of thumb the Moon will be at its highest in the night sky for the Northern Hemisphere in the fall and winter months, lowest in the night sky during the spring and summer months; the same holds true in the Southern Hemisphere, but remember that their seasons are opposite those of the Northern Hemisphere. Because you won’t be using a telescope at sea the Moon’s maximum or minimum height above the horizon really isn’t a concern. The Moon will always rise and set on the sea horizon, which is always a magic moment as you shall see.

As we discussed in Chap. 4 if you are deep down under in the Southern Hemisphere you will also notice that the Moon looks upside down compared to how it appears in the Northern Hemisphere and lingers much farther towards the northern horizon. This can be a bit disorienting when you experience it for the first time! But it does make for fascinating photographs, as you can see (Figs. 9.1 and 9.2).

Fig. 9.1

Object viewed: Full Moon. (Image by the author)

Ship: Azamara Quest

Lens used: 55–200 mm at 200 mm f/5.6 DX and cropped

ISO : 1000

Exposure: 1/3200 second

Comment: Full Moon as seen off the coast of Australia. Moon is literally upside down for those used to seeing the Moon in the northern sky

Fig. 9.2

Object viewed: Full Moon. (Image by the author)

Ship: Explorer

Lens used: 28–300 mm at 300 mm f/5.6

ISO : 800

Exposure: 1/5000 second

Comment: Full Moon as seen off the coast of Funchal. Compare with Fig. 9.1

The night sky right after sunset will be at its darkest when the Moon is new. This is when there will be no moonlight in the night sky at all, so the stars and the Milky Way, if it’s visible, will be at their best. The new Moon would be the time when you want to take pictures of the night sky from dusk until dawn. For a few days after the new Moon the waxing crescent Moon will be visible in the west just after sunset. The thin crescent is striking, and if the sky conditions are clear, you will probably see Earthshine.

We see the illuminated portions of the Moon because of sunlight falling on the lunar surface that is reflected back into space. The line between the illuminated and dark portions of the Moon is called the terminator, and you will see it advance across the Moon during the lunar month. Earthshine can be visible when the Moon is in a crescent phase near the horizon and will make the dark portion of the Moon a gray-blue color. The Earthshine is caused by the reflection of sunlight off our planet’s clouds (primary source) and oceans that illuminates the lunar surface, sometimes to the point that lunar features are easily seen and photographed. If the crescent Moon is at its closest to the Earth for the lunar month, known as perigee, Earthshine can be more prnounced in appearance. Your astronomical software and references will advise you of this and provide you the distance to Earth. Leonardo da Vinci (1452–1519) figured out the mystery of Earthshine, which he published in his Codex Leicester, circa 1510. He thought Earth’s oceans were the source of the ashen glow, but we know today that clouds are the primary source. Earthshine is also known as the “Da Vinci glow” (Fig. 9.3).

Fig. 9.3

Object viewed: Moon. (Image by the author)

Ship: Westerdam

Lens used: 28–300 mm at 300 mm f/5.6

ISO : 10,000

Exposure: 1/10 second

Comment: Earthshine waxing crescent Moon taken at high ISO due to ship motion. Even though the picture is a little blurred it still shows the Earthshine

Seeing the Moon at this phase is beautiful, and if the Moon is close to the sea horizon the Moon’s light will possibly be seen in the water. This is tough to see when the Moon is only a day or two old (days after the new Moon), as it is not long after sunset that the Moon sets. But it is worth getting out right after sunset to start looking. Your software will tell you where the Moon is altitude- and azimuth-wise so you can narrow down your search area; binoculars help immensely in finding the young Moon.

Take note, the same conditions just described will be present in the east before sunrise when the Moon is a waning crescent or several days before it becomes a new Moon. The only difference between the two circumstances is the Moon’s position in the sky, the illumination/orientation of the Moon’s crescent and the timing of when the Moon can be seen. You will probably experience both viewing circumstances if you are out at sea for two weeks or more (Fig. 9.4).

Fig. 9.4

Object viewed: Moon. (Image by the author)

Ship: Azamara Journey

Lens used: 28–300 mm at 300 mm f/5.6

ISO : 1000

Exposure: 1/400 second

Comment: Waning crescent Moon down under. Moon phases taken with telephoto lenses can be quite nice to get

You will also want to be aware of the Moon being near any of the planets. There is nothing prettier than a thin crescent Moon with Earthshine being near the brilliant planet Venus, as you saw in Chap. 8. Seeing this sight and photographing it will be a highlight of any cruise. When the Moon and Venus are near the horizon they both will cast their light on the water, which will be an amazing photograph to take as you saw in (Fig. 8.​5). The Moon teaming up with planets is always a pic worth taking as you can see in (Fig. 9.5).

Fig. 9.5

Object viewed: Earthine Waning Crescent Moon with Jupiter and Mercury. (Image by the author)

Ship: Azamara Journey  

Lens used: 28–300-mm at 92 mm f/5.4

ISO : 1250

Exposure: 1/4 second

Comment: Earthshine waning crescent Moon with Jupiter and Mercury (lower right) off the California coast

The crescent Moon can also pass near star clusters such as the Pleiades and Hyades in Taurus; this would make a pretty picture. If the Moon is just a few days old or it is after the last quarter it is also possible to get some of the Milky Way in the same photograph, as you saw in Chap. 7.

Sometimes the Moon can actually get so close to a planet or star that it occults or actually blocks it from our view in a lunar occultation. These events are pretty amazing to see in a telescope, especially if it is a grazing lunar occultation, in which the star or planet skims the lunar limb. The star or planet winks in and out as it passes behind craters, mountains or valleys. These events have been used to update the topography of the lunar limb. On ship you may be able to view such an event with binoculars or a long focal length lens.

However, the one thing you can only get at sea that no landlubber can is the moonlight on the waves of the sea. You will never, ever tire of seeing the Moon and ocean in concert with one another; the visual tapestry they weave will take your breath away. A full Moon rising or setting near the horizon will offer a kaleidoscope of possible colors depending on the atmosphere and sea conditions. Will it be blinding white, mellow yellow or stunning orange-red? Who knows? Only by looking can you tell.

The presence of clouds when the Moon is up is a positive contributor as well to the raw beauty of sea and sky. The Moon will illuminate the clouds and produce incredible shadow and light patterns that dance on the waves and paint the sky. On most full Moon nights you can notice the presence of what can be called “moonlight blue” – a deep and glorious blue color that dominates the sky near the Moon. It’s unlikely that any of the art masters of old could produce such a color on their own. It photographs well and is best seen when clouds block the brilliant full Moon so that the surrounding sky can be better seen. Make sure you look for this when viewing the full Moon (Figs. 9.6, 9.7, and 9.8).

Fig. 9.6

Object viewed: Full Moon. (Image by the author)

Ship: Grandeur of the Seas

Lens used: 18–55 mm at 55 mm f/4 DX

ISO : 800

Exposure: 1/2 second

Comment: Full Moon on the water

Fig. 9.7

Object viewed: Moon and clouds. (Image by the author)

Ship: Grandeur of the Seas

Lens used: 18–55-mm at 18 mm f/4 DX

ISO: 800

Exposure: 2.3 seconds

Comment: Moon and clouds light up the sky

Fig. 9.8

Object viewed: Moonlight blue. (Image by the author)

Ship: Queen Victoria

Lens used: 28–300 mm at 28 mm f/3.5

ISO: 4000

Exposure: 1 second

Comment: “Moonlight blue” really shows in this picture of the Moon and clouds

One last aspect for you to consider regarding the Moon is taking pictures of the Moon with your ship in the frame. This adds a really neat perspective that blends sea, sky and ship in one view (Fig. 9.9).

Fig. 9.9

Object viewed: Moon and more. (Image by the author)

Ship: Prinsendam

Lens used: 14-mm f/2.8

ISO : 3200

Exposure: 10 seconds

Comment: “Moonlight blue,” with Moon off the starboard bow. There are stars, waves, clouds and a ship….What more could you ask for?

Photographing the Moon

The Moon presents some unique challenges in photographing it, due to the very wide range of illumination and composition possibilities. As it goes through the lunar month and its associated phases you can encounter a dim crescent Moon in a bright dawn/dusk sky or a full blown full Moon that overwhelms any attempt at a time exposure.

The primary consideration becomes what will be the main focus of your photograph? Will it be the Moon itself, its pairing with a planet or star field, or its interaction with the sea and/or clouds? Once you have decided that, you can approach taking your photograph accordingly. To make this as easy as possible we have broken this section into segments aligned with the goal of the photograph.

Astrophoto Tip

Of course, you can also take two pictures and combine them with available photo processing software. This is not a true representation of what was in the sky at the time you took your shot. However, as long as you state that your picture is a combination of exposures, this technique is okay to use.

Moon Phases

If your primary goal is to photograph the Moon as it goes through its phases, your task is fairly easy. To get the most detail you will need a telephoto lens – a 28–300 mm f/5.6, for example. You can use a 35-mm or 50-mm; the Moon’s image will be small but still recognizable.

You can use a prime or telephoto lens for your shot, but at sea the 28–300-mm is quite effective for several reasons. First, with the zoom capability you can frame the Moon and other objects such as planets or stars to get the best composition size. Second, the ability to go full zoom to 300 mm provides sufficient detail, especially with cropping during processing. Third, you can use this lens to great effect during your time ashore photographing close-ups or zoom subjects.

When using a telephoto lens it is helpful to have a tripod or brace yourself on the ship’s structure to steady your shot as much as possible. This is more crucial when the Moon is in a waxing/waning crescent phase, as you will have to take a longer exposure, even though it will be taken in fairly bright dusk conditions to capture the relatively dim Moon. And getting the Earthshine is tricky on a very young or very old Moon, as with the telephoto you will be amplifying the ship’s motion as well as that of the Moon itself, so you are in a constant trade-off between exposure time versus these motions.

Try ISO 800 to 1000, lens wide open, 1/2 second as an initial shot. SAAS.

As the Moon proceeds through the lunar month and its phases the amount of sunlight visible increases daily. This reveals more of the Moon’s features and makes it brighter each day to first quarter, the point at which the Moon is half day and half night, perfectly split in two. This is an interesting phase to photograph, and the Moon dominates the night sky until it sets at midnight.

Try ISO 400 to 800, 1/250 second. SAAS.

From first quarter to full Moon, called a waxing gibbous Moon, the Moon gets really bright and presents its full face to us. A full Moon rising at sunset is a spectacular sight at sea, as the horizon is unobstructed. You can check the time of moonrise for your location using your software and also what the azimuth will be. Knowing these two items will allow you to set up and be ready to look for the Moon at the moment of moonrise.

The Moon will probably be distorted and show some color due to Earth’s atmosphere. This is what you want to be on the lookout for. As the Moon rises it will also cast its light upon the water, and if your ship is headed directly towards or away from the point of moonrise this makes for a spectacular ship shot, as you can see in some of the photographs in this chapter. Be sure to look for the moonlight blue color in the sky when the full Moon is well up in the sky.

Try ISO 400 to 800, 1/500 second for full Moon high in the sky. Horizon full Moon shots will need a longer exposure; try 1/250 second.

After the full Moon the waning gibbous Moon rises later each night after sunset. The amount of sunlight illuminating the surface of the Moon decreases as well each night.

Try ISO 400–800, 1/250 second. SAAS.

The waning gibbous Moon leads to the last quarter Moon, which rises after midnight and is again half daylight, half night, like the first quarter Moon but with the night and day sides flipped.

Try ISO 400 to 800, 1/250 second, SAAS.

After the last quarter the Moon is in the waning crescent phase until the new Moon, when the Moon is not visible and the lunar month begins anew. We previously discussed this phase.

Moon and Planets

Photographing the Moon with the visible planets takes some thought and planning. You have to monitor what is in the sky in order to know when such opportunities will take place. Your software can help you, but this is where having a month by month reference such as the Observer’s Handbook or Sky & Telescope magazine really helps. You have to take advantage of every waxing/waning crescent Moon and Venus opportunity that comes along. There is nothing quite like seeing and photographing this celestial duo – with Earthshine as well – near the sea horizon with their separate reflections on the water.

Will the shot be at dusk, dawn or night? And with which planet(s)? This is what makes taking the Moon’s photograph with the planets challenging – what will be the background sky’s lighting and what will be the brightness of the planet(s)? You can use the previous section’s settings for each of the Moon’s phases as a start, but you will probably have to expose a bit longer to include any planet(s) in your photograph.

Also, what will be the ship’s orientation to your shot? Will it be bow on, stern, amidships? You will have to determine this in order to compose your photograph and insure that there are no interfering light zones. The bow and stern can be part of your picture, or you can aim high to exclude them while amidships can give you a clear view of the sea horizon unless you want the deck rails included.

You can try your zoom-telephoto lens to take the picture or a 35- or 50-mm. A wide-angle lens can be used, too, but the image scale will be very small, with the Moon, let alone the planet, showing little beyond a few pixels. The trick here is to get your best photograph without the Moon becoming overexposed, if at all possible. The brighter planets will help avoid this, as you can take a faster exposure time. You will have to shoot multiple pics to hopefully get a good one.

Lunar Occultation of a Planet or Star

Your considerations will be exactly the same as the preceding section except the Moon and the object being occulted will be right next to one another. That really necessities using a long focal length lens so you can see the object being occulted. You may see the object being occulted disappear, wink in and out, reappear or just one of these possibilities. This is where your Observer’s Handbook or other reference and astronomical software can help you out. How you photograph the event will depend a lot on the brightness of the occulted object and phase of the Moon. A full Moon may wash out a dim star, while a bright planet and a crescent Earthshine Moon will be a ‘WOW WEE’ event – SAAS big time.

Moon, Water, Clouds

There are few sights more inspirational, romantic and dramatic than moonlight upon the water. The sea and Moon present an ever-changing canvas of light, shadow and color. And believe it or not, the presence of clouds – as long as they do not totally obscure the sky – add a dimension that you will not believe until you see and photograph them.

Perhaps the best time to photograph this combination of Moon, water, and clouds is when the Moon is near or at full phase, which your software can advise you of. That is because this is the time when the Moon is putting out the maximum amount of light that can interplay with the sky, water and clouds to produce the most dramatic reflections, shadows and colors.

The waves present themselves with their moonlit panorama, which can vary from glassy smoothness to roiling waves throwing off sea spray. Shafts of moonlight and shadow can fall upon the sea and paint it in an ever-changing perspective. Meanwhile, Moonlight Blue may color the sky to accompany clouds bathed in moonlight – possibly with stars in the background for an added photographic bonus.

To maximize your shooting capability you should use a tripod, as your exposure may be seconds long if you are trying to get the most from the sky. You can vary your ISO from 1000 to 3200 to help with exposure times. A 35-mm or 50-mm lens will give you decent area coverage and image detail. You can use a telephoto if there is something you want to highlight, but this takes away the overall frame coverage, which is what you really want in these kinds of photographs. A wide-angle lens can be useful to obtain maximum coverage of sea and sky with less detail.

Your exposure time really depends on what you are trying to make the focus of your photograph – Moon, clouds, waves or all of them combined. Shorter exposure times will “freeze” the motion of the waves but still capture other details. Longer exposures will bring out the Moonlight Blue, clouds and stars. You can frame your shot to get all of these components together, but your exposure time will be longer as a result. SAAS is the name of the game in anything involving the Moon, especially here.

© Springer Nature Switzerland AG 2018

Gregory I. RedfernCruise Ship Astronomy and AstrophotographyThe Patrick Moore Practical Astronomy Serieshttps://doi.org/10.1007/978-3-030-00958-8_10

10. Eclipses

Gregory I. Redfern1  

(1)

NASA JPL Solar System Ambassador, Ruckersville, VA, USA

Gregory I. Redfern

This chapter is all about eclipses but let’s get the most important thing out of the way first – solar eclipse safety. Failure to follow solar eclipse viewing and solar eclipse photography safety procedures will cause permanent eye damage as well as ruin your camera. These procedures were discussed in the earlier chapter, but we will repeat them here briefly. For more details, see Chap. 5 in this book.

1.

NEVER look at the Sun (except during totality of a total solar eclipse) unless you have approved and certified solar viewing glasses with certification ISO 12312-2, also known informally as solar eclipse glasses – for your eyes.

2.

NEVER photograph or look at the Sun unless you have an approved and certified solar filter that properly fits the front of the lens you are using. You also need to have an approved and certified solar filter for the sunward side of each optical aid you bring along to observe/photograph the Sun.

3.

NEVER photograph or look at the Sun through a viewfinder unless you have an approved and certified solar filter over the viewfinder, if your camera lacks through-the-lens viewing. The viewfinders of digital single-lens reflex cameras (DSLRs) are made safe by the approved andcertified solar filter in front of the lens.

4.

As an extra precaution even when using your approved and certified solar filter(s) and solar viewing glasses DO NOT STARE for long periods at the Sun or through your camera’s viewfinder, again in case of holes or other imperfections in the solar filter and solar viewing glasses. If available, use your camera’s LIVE VIEW function. Look only for a few seconds, and then look away.

5.

There is little information available on how to safely photograph solar eclipses using tablets. Accordingly you will find no information in this chapter on how to do so. Since you wouldn’t be looking through them, there is no way you could hurt your eyes, but the tablet’s lens focusing on the Sun could damage the tablet’s camera.

6.

PRINT OUT the solar eclipse safety section links for this chapter included in the Appendix of this book to take with you to sea in case you cannot access the Internet. If the link(s) do not work when you try to access them refer to https://eclipse.gsfc.nasa.gov/SEhelp/safety.html and https://aas.org/eye-safety.

7.

DO NOT attempt to view or photograph solar eclipses unless you completely understand the procedures required to do so safely. If you do not understand them, contact the appropriate organization for clarification. This chapter is intended as an introduction only, as whole books have been written on viewing and photographing eclipses. Some are listed in the Appendix of this book.

A list of reputable vendors for purchasing approved and certified ISO 12312-2 solar eclipse glasses (used for your eyes only) and solar filters for your camera and optical aid gear have been included in the Appendix of this book. (See also https://​eclipse.​aas.​org/​eye-safety from the American Astronomical Society.) Follow the guidelines and manufacturer’s instructions for their use and how to check them before each use.

An eclipse (unless specified, hereafter the term ‘eclipse’ will refer to both lunar eclipses and solar eclipses) of the Sun or Moon is always a treat to view and photograph at sea. Each eclipse is different, and we know centuries in advance when eclipses will occur. Besides the solar eclipse safety guidelines in the Suggested Readings and Internet Sites for this chapter in the Appendix, there are several valuable references you can refer to for this information. Eclipses are also covered extensively, including observing tips, in the annual Observer’s Handbook and astronomy magazines such as Sky & Telescope. Your astronomical software will prove its worth also because you will have to input your ship’s actual latitude, longitude and time zone (see Chap. 4) to determine the particulars of an eclipse event for your location at sea.

As mentioned in Chap. 1, some cruise lines will make these astronomical events part of or even central to a cruise. You can research when an eclipse is coming up – I have included some useful solar and lunar eclipse Internet sites in the Appendix of this book. Once you know the dates do an Internet search for ‘eclipse cruises.’ You might even try a follow on search to include the actual date of the solar or lunar eclipse. You will find a surprising number of tour companies that list eclipse cruises. We’ll discuss ship sponsored versus “do it yourself” eclipse events later in the chapter.

Ship Tip

Check to make sure that there is not going to be an eclipse event taking place on a cruise you will be on. I was on a cruise where there was going to be a rare hybrid solar eclipse (WOW!) taking place while we were at sea, and we were not going to be too far from the path of totality/annularity . There was no mention of it in the ship’s cruise itinerary. The ship could have very easily changed her course to get in the path of totality/annularity but for whatever reason didn’t do so.

And also, I hadn’t checked to see what was happening astronomically speaking on this cruise beforehand. Well, imagine my surprise that once I was at sea I checked to see what would be coming up and lo’ and behold the ship would be sailing right into the partial solar eclipse coverage area, very close to the path of totality/annularity. Lesson learned! In my defense this was one of my very first civilian cruises as a special interest astronomy/space exploration speaker and turned out to be quite the tale in many respects. I had no solar filters but safely improvised and was able to take photographs of the event that, for us on board, was a deep partial solar eclipse.

Understanding Eclipses

Solar eclipses can only occur when the new Moon passes directly between the Sun and Earth. Solar eclipses can be total, annular, hybrid or partial.

Lunar eclipses can only occur when Earth passes directly between the Sun and the full Moon. Lunar eclipses can be total, partial or penumbral.

The Moon, like Earth, projects a shadow out into space due to being in constant sunlight. The Moon’s shadow is smaller and shorter than Earth’s because it is a smaller spherical body. The shadows of both the Moon and Earth have two parts: the umbra, or dark inner shadow, and the penumbra, or lighter outer shadow.

Each month we would see a total solar eclipse at the new Moon and then, two weeks later, at the full Moon, a total lunar eclipse – if it weren’t for the fact that the orbit of the Moon is inclined 5 degrees relative to Earth’s orbit around the Sun. As it is we see several of these eclipse events each year, when the orbital geometry of the Sun, Moon and Earth align just right. Solar and lunar eclipse events always happen two weeks apart as a result.

Astronomers prepare detailed “eclipse maps” for each eclipse. It would be extremely useful for you to learn how to read them (see the Appendix of this book) as they will help you determine what eclipse events you might see on a cruise. These maps also provide extensive details about the eclipse that will help you plan your observing and photographing.

For eclipses other than partial eclipses NASA provides an ‘interactive Google map’ (you will need to the able to access the Internet to use them) that allows you to input your location and determine what the eclipse will look like. It also provides the times for key eclipse events. This is very useful for getting eclipse particulars for your predicted location when you are at sea. It will complement the information your astronomical software provides.

Let’s look at solar eclipses first.

The following is not an all-inclusive list of data provided by a solar eclipse map , but it does highlight major features. Solar eclipse maps will include:

A diagram of Earth centered on the geographical region where the eclipse will be seen and show the entire viewing area.

What type of eclipse it is, Universal Date and time for key eclipse events that are particular to the type of eclipse involved.

The geographical beginning and ending points, the upper and lower limits of the partial eclipse, the path of totality and/or annularity ; this will vary depending on what type of eclipse it is – total, annular, hybrid or partial.

Areas of eclipse magnitude (the fraction of the Sun’s diameter occulted by the Moon) expressed as a percentage.

Areas of eclipse obscuration (the fraction of the Sun’s area covered by the Moon) expressed as a percentage.

A total solar eclipse involves the new Moon slowly (or so it seems!) moving across the face of the Sun. During the partial eclipse phase the Moon covers the Sun to an ever larger percentage until the Sun is totally eclipsed. During this partial eclipse phase we see the Moon’s outer shadow, the penumbra.

When the Sun is totally eclipsed we see and experience the Moon’s umbra and the Sun’s corona (more about this later). The amount of time the Sun is totally eclipsed is called totality, and it can last from a fraction of a second up to a maximum of about 7.5 minutes. Each location on Earth that is within the precisely defined path of totality, the path of the Moon’s dark umbra shadow on the surface of Earth, has a specified length of totality measured in seconds and/or minutes.

The time of totality will vary depending on where you are within this path. If you are on the path’s center line you will experience a longer duration of totality; only one specific point on the path will experience the greatest duration of totality. If you are in the totality upper limit line, or totality lower limit line, relative to the center line, your time of totality will be reduced. Observers just outside the path of totality will experience a partial solar eclipse, with the highest percentage, 90+%, of the Sun eclipsed to ever-decreasing amounts the farther away you are above or below the path of totality.

After totality ends a partial solar eclipse occurs, as the Moon slowly unmasks the Sun to full brilliance, ending the event. This whole sequence can take several hours from first to last contact with the new Moon.

An annular solar eclipse occurs when the new Moon is at or near apogee, its farthest distance from Earth during the lunar month. Once again the Moon partially eclipses the Sun as it moves, covering more and more of the Sun, but does not completely eclipse the Sun. This is because the Moon’s umbra shadow is too far away to reach the surface of Earth. Instead the antumbra – the part of the Moon’s shadow that extends beyond the umbra – eclipses the Sun. The corona is not visible in this type of eclipse, as the brilliant Sun is always present. The annular solar eclipse map will be virtually the same as that for a total solar eclipse.

If you are within the path of annularity you will see the dark Moon silhouetted against the Sun by a brilliant ring, or annulus, around it. Annularity – the time the Moon’s entire disk is seen silhouetted against the Sun – can last from a fraction of a second to a maximum of 12 minutes, 29 seconds.

After annularity ends, a partial solar eclipse occurs, as the Moon slowly unmasks the Sun to full brilliance, ending the event. This whole sequence can take several hours from first to last contact with the New Moon.

During rare hybrid solar eclipses , also known as annular/total eclipses, the eclipse appears annular and total along different sections of its eclipse path. Most hybrid eclipses begin as annular, change into total and then switch back to annular before the end of their eclipse track. In a rare occurrence, a hybrid eclipse may begin annular and end total, or vice versa. These eclipses are caused when the curvature of Earth brings locations within the path of annularity/totality into the umbra and antumbra shadows. The hybrid solar eclipse map will look the same as the others.

EXTREME CAUTION must be exercised in this type of eclipse, as the Sun will transition quickly from annular to total eclipse or vice versa, necessitating use of an approved and certified solar filter for the front of each of your camera’s lenses and optical aid and approved and certified solar eclipse glasses with certification ISO 12312-2 for viewing the annular eclipse phase.

The Google map for the eclipse will show the predicted eclipse type for a selected location – annular or total – but during the transition between totality and annularity or vice versa you must be prepared to quickly use your approved and certified solar filters on your camera lenses and optical aid and approved and certified ISO 12312-2 solar eclipse glasses for viewing the Sun.

The new Moon once again does its partial eclipse dance with the Sun until annularity/totality , at which point the observer will view either a total or annular eclipse.

After totality/annularity ends a partial solar eclipse occurs, as the Moon slowly unmasks the Sun to full brilliance, ending the event. This whole sequence can take several hours to occur from first to last contact with the new Moon. This type of eclipse is a rare event.

As you have seen the Sun is partially eclipsed before and after totality or annularity occurs. Partial solar eclipses also occur and are the most common type of solar eclipse. The solar eclipse map is the same, except it does not have a path of totality or annularity specified. The map shows the geographic area of eclipse visibility marked by lines showing the percentage of the Sun eclipsed within them. Partial solar eclipses can just barely eclipse, or cover a majority of the Sun. No corona is visible.

Preparing for Solar Eclipses

Before proceeding, have you read and understood the solar eclipse safety information at the beginning of this chapter and contained in the solar eclipse safety guideline links provided in the Appendix of this book for this chapter? If not, please do so before attempting any solar eclipse viewing or photography.

Insure that you have the proper size and approved and certified solar filter that goes over the front of each of your lenses and any optical aid that you will be using and approved and certified ISO 12312-2 solar eclipse glasses for your eyes. Make sure that you read and follow the guidelines and instructions for using and inspecting your solar eclipse glasses and camera lenses/optical aid solar filter(s) before each use.

My two solar eclipse photographic experiences at sea involve using a “wet film” 35-mm single lens reflex (SLR) camera with a 50-mm lens and an 8-mm tape video recorder for a total solar eclipse and a digital single lens reflex camera (DSLR) with various lenses for a 95% partial solar eclipse.

On land I have seen and photographed one total solar eclipse , one annular eclipse and about a dozen partial solar eclipses. I have used the SLR attached to various telescopes, the DSLR with a long focal length zoom telephoto lens mounted on a telescope mount and an iPhone 6s to take pictures while in the umbra. I have never seen the rare hybrid solar eclipse.

Based upon experience and the pictures obtained using a modern DSLR camera it is the most versatile and best of your photographic options for solar eclipses. For other camera types (except tablet/iPad users for which we have no reliable information available) refer to the Appendix in this book for solar eclipse photography.

There is nothing, absolutely nothing that can compare to seeing the totally eclipsed Sun with the darkened sky and corona at sea. Well, maybe photographing it! But even then you have to make sure to take time to visually enjoy the view as well. If you are in a group, or even by yourself, when totality happens, you will know it from the primal screams that erupt. You just can’t help it. You are in the deep umbra shadow of the Moon, which only extends a relatively short distance (a hundred miles or so) across Earth’s surface and is moving perhaps several thousand miles an hour. Again the circumstances are different for each eclipse.

Inside the umbra the sky and sea are darkened, bright stars and planets are visible, the totally eclipsed Sun hangs suspended within the ghostly corona (the Sun’s million-degree outer atmosphere) eerily surrounding the Sun perhaps several solar diameters in length. The corona is simply spectacular and can never be seen outside of a total solar eclipse without special instruments; even then it is only the outer portion of the corona that is visible, the inner portion that is closest to the Sun can only be seen during a total solar eclipse. You can glimpse full daylight on both sides of the umbra, which is really a stunning view.

In planning for your solar eclipse (or lunar eclipse), the biggest question is whether the ship will be making this a ship-wide event or will you be on your own. A ship-sponsored event will likely have experts onboard giving lectures, providing advice and actually working in concert with the ship’s staff to coordinate the event. The ship may provide solar eclipse viewing glasses, provide unique memorabilia of the event, and provide written information about the eclipse. On Statendam the eclipse leader, the late Leif Robinson of Sky & Telescope, used the ship’s public announcement system to guide everyone through the entire eclipse. This was very high class, and it is highly recommended going this route if you can.

If you find out there is a solar (or lunar) eclipse event occurring on your cruise and you don’t see any mention of it in the itinerary, it doesn’t hurt to inquire with the cruise company beforehand. See what they say. If you are already at sea, inquire at the front desk or ask the cruise director if the ship is aware of the event and if they are doing anything special for it. If they aren’t, ask if someone on staff in the front office could help you with getting the information that you will need.

You will have to determine your ship’s projected position and time zone during the eclipse, in order to establish date and time, how high or low in the sky the eclipse occurs and what the azimuth will be. Then you will have to determine what the ship’s course will be during the eclipse and select the best location on ship to view the event.

Writing your questions is best, and politely ask if they can be passed on to the navigator. Knowing your precise position gets critical only if you think you are going to be in the path of totality or annularity. If so you really need precision; if not, then getting the ship’s position off of the ship’s navigation channel will suffice, as you will be in a partial eclipse and a much larger viewing area.

To photograph the event you will want a location on the ship that has a clear view of the sky where the eclipse will take place. Remember this event will possibly be hours in length, and the Sun will be moving to the west, so make sure you have a clear view start to finish. If possible get near the ship’s center line to minimize ship rolling.

There are likely to be large crowds on deck, so you will want to “stake out your place” early.

Odds are there are probably other like-minded individuals on board, and you may meet them if time permits before the eclipse. It might be nice to team up and exchange ideas and work together.

My total solar eclipse at sea and the first one I ever observed and photographed occurred February 26, 1998, and was on Holland America’s Statendam , which was part of a three-ship fleet that was a dedicated total solar eclipse cruise tour. The three ships sailed together for ten days and were successful in viewing the entire total solar eclipse. It was a good thing I was on a cruise ship, because the ships had to move around to find a good viewing spot free of clouds – a huge advantage for ships at sea.

You may want to use a tripod if you have one. You can brace yourself, and camera, against the ship also. If the ship is significantly moving about you will probably be better off shooting handheld. If your lens has “Vibration Reduction” make sure you turn it on. If the Sun is high in the sky will your tripod work with the lens you choose and leave you room to work behind the camera?

Have a deck chair to sit on, a Sun hat with a flexible brim so you won’t bump the camera if you get too close and wear sunscreen or sun pants and shirt. You might tie a wet scarf on your neck to help cool down and have water bottles to drink and wet the scarf. Have extra batteries and digital storage for your camera available just in case. Use a cable/shutter release to minimize vibration; do not use the shutter delay if your camera has it, because you do not want to lose any precious seconds during the eclipse.

What type of lens you use depends on what you want to capture, maybe the corona and totally eclipsed Sun, or a wide view of sky and sea? Remember, changing lenses loses precious seconds in totality. Also, if you plan on using different lenses you will need an approved and certified solar filter of proper size for the front of each lens.

Be sure to check the references on solar eclipse photography and videography in the Appendix of this book. Essentially you need a long focal length lens, prime or zoom, to get greater image detail of any solar eclipse, especially if you want to capture totality and the corona, or annularity. Consider a zoom lens or a catadioptric lens (uses a mirror) with an extender; 300-mm is considered the smallest useful focal length and 1000-mm is desirable. This will show nicely the various features you are about to learn about.

A 50-mm lens gives you a small image size of the Sun and corona, but it provides nice coverage. It can show planets, stars, the eclipsed Sun and the corona in a full-sized FX frame; DX frame size will lose some coverage but will still be fairly wide.

A wide-angle lens will give you hardly any image detail of the Sun, but should give you the corona and bright planets. Plus, you might be able to get the sea in the picture, too, depending on how far above the horizon the Sun is for the eclipse.

The Sun will still be bright even as the Sun approaches totality. Even at totality the corona is as bright as the full Moon. So shutter speeds can be fairly fast, with the proper ISO to offset any ship motion. Consult the provided references and the settings information on the images in this chapter for a start.

For greatest efficiency it is recommended that you make up an “Eclipse Plan.” This will help organize your information and planned photographic coverage of the eclipse as a ready reference. Time really flies at totality, so you want to know what you plan to do. You will probably have to make changes due to conditions or photographic results, but you have to start somewhere.

Following is a suggested format for such a plan. Your first step, though, should be to review the solar eclipse safety guidelines. For example, do you have approved and certified and proper-size solar filters for the front of each camera lens and optical aid to be used? Do you have approved and certified ISO 12312-2 solar eclipse glasses?

Eclipse Type

Input type of eclipse (solar or lunar with type).

Ship’s Date

Actual date(s) of the eclipse for the ship.

Ship’s Time for Eclipse Events

From the Eclipse Map for the event, list the ship’s time for each major event – essentially the contact times. For a total solar eclipse add an event for Baily’s Beads and the Diamond Ring effect before and after totality , as a means to remind you to be on the alert for their appearance.

Sun’s Altitude/Azimuth

START:

TOTALITY/ANNULARITY/MAXIMUM OF A PARTIAL ECLIPSE:

END:

Planned Photographic Settings

For each event in the eclipse map, including Baily’s Beads and the Diamond Ring, before and after totality list your planned (initial):

LENS and approved proper size solar filter to be used on the front lens:

ISO :

CAMERA SETTINGS MODE: Manual mode is recommended for shutter speed and aperture for best results.

FOCUS MODE: Manual mode with pre-focusing to “infinity” is recommended.

FILE TYPE: RAW is recommended to provide greatest flexibility in processing pictures.

FLASH: Off

TRIPOD, HANDHELD, SHIP BRACE:

Photographing a Total Solar Eclipses

Remember, you must have an approved and certified solar filter of the proper size on the front of each camera lens and optical aid used and approved and certified ISO 12312-2 solar eclipse glasses on your eyes when looking at the Sun and during the partial eclipse phase before and after totality. Only when the Sun is totally eclipsed can you remove the solar filters and solar eclipse glasses. You will need to keep them very close by to use again and quickly when totality ends.

Hopefully you will have practiced removing and putting the solar filter on the front of your lens in advance. If not, point your camera away from the Sun and do a couple of practice runs. You want to be as smooth as you can be in removing and putting the solar filter on the front of your lens so as to avoid jostling the camera and lens. Also make sure that the solar filter is properly placed on the front of your lens so it will not fall off. Check it often to make sure it is properly in place.

You want to achieve precise focus before the eclipse starts. Focus on a distant part of the ship or the sea horizon . Once you have achieved focus, note where the “Infinity” symbol is located on your lens focus ring in case you have to refocus. If your camera has it, use LIVE VIEW with “zoom in” for a magnified image to get that last little bit of precision focus. Place the approved and certified and proper size solar filter on your front lens, being careful not to jostle the focus ring.

Astrophoto Tip

If you use a mirror camera lens you will have to refocus each time after attaching or removing your solar filter.

Your lens will be at “Infinity” focus for the Sun. You will have plenty of time before the partial solar eclipse phase begins to re-check your focus. With the solar filter securely on the front of your lens aim your camera at the Sun (use LIVE VIEW if you have it) and check the focus on the limb of the Sun or sunspots if they are visible. Remember, DO NOT stare at the Sun for long periods through your camera’s viewfinder, as an added eye safety precaution. Take a couple of test shots to see how they look and to insure focus. Move your camera off of the Sun until just before the partial solar eclipse phase starts.

Upon achieving perfect focus put a piece of clear tape – duct tape may leave a residue – over the focus ring and lens body to help prevent their accidental movement during the eclipse and totality. You also may want to apply some clear tape to a zoom ring if using a zoom telephoto so it doesn’t move on you, although this may not be a good idea if you are going to work the zoom lens during the solar eclipse.

Another reason you may want to consider doing this is to avoid accidentally losing focus when you remove your solar filter, as it is a snug fit (a good thing) and takes a bit of a grip to remove it. This is normal as you do not want a solar filter that can come off of your lens easily.

Astrophoto Tip

For the February 1998 total solar eclipse at sea I used a 40-power optical zoom 8-mm video camera, with an approved glass solar filter which got great results. I have yet to get it digitized so I can access the footage in other than video tape format. I also shot High Speed Ektachrome (ASA 400!!!) slides during totality only with my Minolta SRT-101 50 mm f/1.2 and have included two of them that I digitized.

Shooting video with a DSLR using an approved and certified glass solar filter for your lens(es) is a great way to photograph eclipses. You can switch between video recording and individual shots very easily. You can also pull individual frames from the video to process into individual shots.

The partially eclipsed Sun and totality might be bright enough with modern cameras to autofocus but you need to check this out before the eclipse begins. If not, pre-focus as previously described on the Sun or sea horizon in manual focus mode.

Below are land-based astrophotographs from the August 21, 2017, total solar eclipse for illustrative purposes. The camera settings would be appropriate for taking photographs of a total solar eclipse at sea. Approved and certified front lens and optical aid solar filters and ISO 12312-2 eclipse glasses are required during the entire partial eclipse phases, including during the Diamond Ring effect and Bailey’s Beads that occur right before and after totality (Figs. 10.3 and 10.4).

Fig. 10.1

Object viewed: Initial partial eclipse phase. (Image by the author)

Lens used: 200–500 mm w/ 1.7x for 850 mm at f/9.5

ISO : 200

Exposure: 1/640 second

Comment: The Moon has just started to partially eclipse the Sun

Fig. 10.2

Object viewed: Deep Partial eclipse. (Image by the author)

Lens used: 200–500 mm w/ 1.7x for 850 mm at f/9.5

ISO: 200

Exposure: 1/160 second

Comment: Deep partial eclipse phase, almost at totality

Just before the Moon totally covers the Sun, and immediately after the Moon starts to uncover the Sun, a flash of sunlight causes the Diamond Ring effect . This flash of sunlight looks for all the world like a diamond ring hanging high in the darkened sky (Fig. 10.3).

Fig. 10.3

Object viewed: Diamond Ring effect. (Image by the author)

Lens used: 200–500-mm w/ 1.7x for 340 mm at f/9.5

ISO : 200

Exposure: 1 second

Comment: The famous Diamond Ring. This was the one after totality

You may witness Baily’s Beads, which is the very last glimmer of sunlight passing through valleys and depressions along the limb of the Moon before totality. It almost looks like the last of the visible sunlight is “dancing” as the Sun fades into total eclipse. These will also appear just as totality ends (Fig. 10.4).

Fig. 10.4

Object viewed: Baily’s Beads. (Image by the author)

Lens used: 200–500 mm w/ 1.7x for 850 mm at f/9.5

ISO: 200

Comment: Looking like a mirage, Baily’s Beads

Totality begins after the Diamond Ring effect and Baily’s Beads have occurred.

Solar filter and eclipse glasses are taken off during totality. They need to be kept very close so they can be put back on when totality ends. The time of totality – the actual length of time the Sun is totally eclipsed by the Moon – is different for every eclipse and can be from seconds to minutes. The length of totality is dependent on many factors, and no matter how long it is the time goes by very fast! (Figs. 10.5 and 10.6).

Fig. 10.5

Object viewed: Solar corona at totality. (Image by the author)

Ship: Statendam

Lens used: 50 mm f/1.2

ISO : ASA 400 film

Exposure: Unknown

Comment: The Sun is totally eclipsed, Mercury, Jupiter and the corona is visible. The shadow of the Moon over the Caribbean Sea

Fig. 10.6

Object viewed: corona Inside the umbra. (Image by the author)

Ship: Statendam

Lens used: 50 mm f/1.2

ISO : ASA 400 film

Exposure: Unknown

Comment: The shadow of the Moon over the Caribbean Sea

Here are some total solar eclipse pictures taken in Cookeville, Tennessee, on August 21, 2017.

Fig. 10.7

Object viewed: Totality with inner corona. (Image by the author)

Lens used: 200–500 mm w/1.7x for 340 mm at f/9.5

ISO: 200

Exposure: 1/160 second

Comment: Totality and inner corona revealed

This second totality picture is another frame from a video that shows the red color of the chromosphere, which is part of the Sun’s atmosphere. It exists between the photosphere, which is the gaseous “surface” of the Sun that we normally see when viewing the Sun (of course, with a properly and safely filtered telescope) and the corona. The temperature increases by over 10,000 degrees from the photosphere to the chromosphere, causing the hydrogen gas to emit the red color we see. You can also see solar prominences in the picture; these are filaments of plasma, a hot gas made up of electrically charged hydrogen and helium that flows along magnetic field lines (Figs. 10.8 and 10.9).

Fig. 10.8

Object viewed: Totality with inner corona, chromosphere and prominences. (Image by the author)

Video frame

Lens used: 200–500 mm w/ 1.7x for 850 mm at f/9.5

Comment: Here, solar activity, along with the red color of the chromosphere, are easily seen

Fig. 10.9

Object viewed: Totality with inner and outer corona. (Image by the author)

Lens used: 200–500 mm w/ 1.7x for 340 mm at f/9.5

ISO : 200

Exposure: 1/3 second

Comment: Corona revealed. My best picture of the eclipse. Regulus is the star at left. Blue color is real

Figure 10.10 is a highly enhanced photograph that shows the solar prominences around the limb of the Sun.

Fig. 10.10

Object viewed: Totality with prominences. (Image by the author)

Lens used: 200–500 mm w/ 1.7x for 340 mm at f/9.5

ISO : 200

Exposure: 1/160 second

Comment: Multiple prominences seen during totality

Fig. 10.11

Object viewed: Inside the umbra. (Image by the author)

iPhone 6s

Comment: In the Moon’s shadow

Fig. 10.12

Object viewed: Inside the umbra. (Image by the author)

iPhone 6s

Comment: In the Moon’s shadow

As the Moon keeps moving across the Sun, you will begin to see brightening on the opposite side from where you saw the Diamond Ring effect just before totality began . This means that totality is ending and you MUST STOP LOOKING directly at the eclipse. Before the first flash of sunlight appears around the edges of the Moon to begin the partial eclipse phase, your solar filter MUST be properly placed on your front lens and optical aid and eclipse glasses used for viewing the Sun.

The Diamond Ring effect and Baily’s Beads will occur again. The partial eclipse phase ends when the Moon moves off of the Sun (Figs. 10.13 and 10.14).

Fig. 10.13

Object viewed: Deep partial solar eclipse phase. (Image by the author)

Lens used: 200–500 mm w/1.7x for 850 mm f/9.5

ISO : 200

Exposure: 1/320 second

Comment: The deeply eclipsed Sun just after totality

Fig. 10.14

Here is the setup used to photograph this wonderful event. The camera and lenses are on a telescope mount to track the Sun. (Image by the author)

Partial Solar Eclipses

Pinhole Projection

There is a very simple, safe technique called pinhole projection (see Suggested Readings) for viewing the eclipse. All you need is a stiff 3x5 card or even a sheet of paper to make a small hole. Have your back towards the Sun – DO NOT look through the pinhole at the Sun –and project the Sun’s image on a flat surface. You can use the ship’s bright white superstructure to project your image, which shows how dark the sky was at the time. Even partly overcast, the sky definitely darkens due to the diminishing sunlight, as you can see in the eerie color of the bright white paint of the ship (Figs. 10.15 and 10.16). This method can also be used during the partial eclipse phases of total and annular eclipses.

Fig. 10.15

Object viewed: Deep partial solar eclipse via pinhole projection. (Image by the author)

Lens used: 18–55 mm f/3.5–5.6 at 55 mm f/5.6

ISO: 200

Exposure: 1/200 second

Comment: The ship takes on an eerie look when the Sun is deep in partial eclipse

Fig. 10.16

Object viewed: Deep partial solar eclipse via pinhole projection and “photobombing fingers.” (Image by the author)

Lens used: 18–55 mm f/3.5–5.6 at 55 mm f/5.6

ISO : 200

Exposure: 1/250 second

Comment: This picture illustrates that just using your fingers can give you a decent eclipse photograph

If you do not have a lens solar filter or solar eclipse glasses, this is the safe way to view and photograph partial and annular solar eclipses .

Photographing the Partial Eclipse

For directly photographing a partial solar eclipse an approved and certified solar filter for covering the FRONT of EACH of your camera lens(es) and EACH optical aid, and viewing the Sun with approved and certified ISO 12312-2 solar eclipse glasses for your eyes only needs to be used for the entire eclipse, as there is no totality and the Sun remains blindingly bright. The planning required and the settings for photographing a partial solar eclipse, are the same as the partial phases of a total solar eclipse.

Photographing Annular Solar Eclipses

An annular eclipse never experiences totality , although the Sun can become deeply eclipsed. It will be a partial solar eclipse before and after annularity, so partial eclipse settings can be used. Your solar map and Google Interactive Map for the event will tell you how much of the Sun will be eclipsed and what it will look like so you can get an idea of what to expect. During the entire annular eclipse (partial eclipse phases and annularity) an approved and certified solar filter for covering the front of your camera lens and each optical aid is required as are approved and certified ISO 12312-2 solar eclipse glasses for your eyes.

Hybrid Solar Eclipses

Using the solar eclipse map and Google interactive map for the event might help you determine the particulars of when and where totality and annularity will occur, but you must use caution so as to not be caught off guard by the sudden appearance of annularity. Be sure to have your solar filters and solar viewing glasses at the ready.

There should be additional safety guidance in the Observer’s Handbook , Sky & Telescope magazine, NASA.gov and AAS.​org about this type of eclipse when it occurs on April 20, 2023. Be sure to check these out prior to the eclipse for the latest information on safely viewing and photographing this rare type of eclipse.

During the partial eclipse phases and the annular eclipse be sure to use an approved and certified solar filter for covering the front of your camera lens and each optical aid and view the Sun only with approved and certified solar eclipse glasses.

Lunar Eclipses

What about lunar eclipses? They are totally safe to watch, needing no eye or camera protection and are very photogenic when the Moon is totally eclipsed, or nearly so, in a deep partial eclipse. They can last for a short period of time with penumbral eclipses and for hours with total and partial lunar eclipses.

There are lunar eclipse maps and a few differences between these and solar eclipse maps. The differences are:

Because a lunar eclipse occurs at night and can be seen by essentially the whole night side of the planet, the map is drawn depicting the entire Earth in a rectangular format. The area coverage of the eclipse is shown, with the key events annotated.

The lunar eclipse map also depicts the Moon’s path through Earth’s penumbra and umbra shadows. It shows the time and point of the Moon’s contact with each shadow entering into and out of the eclipse.

The time durations for each phase of the eclipse is provided.

It is easier to determine the specific circumstances of a lunar eclipse at sea because the visibility area is so much larger than the small path of totality or annularity in a solar eclipse . NASA’s Lunar Eclipse Page has a Javascript Lunar Eclipse Explorer that allows you to select a geographical region and then either a city within the region or input your position to determine the eclipse specifics. This is useful and complements the information your astronomical software provides.

Total lunar eclipses start with Earth’s very faint penumbra shadow moving across the face of the Moon. This is very subtle and difficult to see with the unaided eye. When the umbra appears on the limb of the Moon it is dramatic. As the eclipse proceeds the umbra covers more and more of the Moon. At some point deep in the partial eclipse phase color will begin to emerge on the Moon. It can be a variety of colors, from red, orange, yellow and even brown.

When the Moon is fully covered by the umbra, totality, it can be quite a palette of colors. If the Moon passes very near or on the centerline path through the deepest part of the umbra the color can be orange or kind of a “copper penny” color. If it is near the edges of the umbra it can be a lighter color and have some white mixed in.

Each total lunar eclipse is different in the colors it displays, as the location of the Moon in the umbra and the condition of Earth’s atmosphere are major contributing factors in what colors arise. We see color in and near totality because sunlight passes through our planet’s atmosphere. If there were no atmosphere the Moon would be totally dark. To astronauts on the Moon during a total lunar eclipse they would see a total solar eclipse when looking at Earth, with a red ring around the entire planet caused by all of the sunrises and sunsets. What a view that would be!

The condition of Earth’s atmosphere as determined by the amount of volcanic debris, aerosols and other components present really can make a difference in the amount of sunlight that can pass through. Scientists actually use total lunar eclipses to monitor Earth’s atmosphere. When Mount Pinatubo erupted in the Philippines in 1991, the total lunar eclipse the following year as viewed by the author on Guam was so dark as to be almost invisible at totality. The Moon was a very dark brown, an indication of how much material and gases the volcano had lofted up into the high atmosphere.

A partial lunar eclipse will have the hard to see penumbral eclipse phase and then the dark and curved umbra. It is exciting to see the actual curvature of our planet move across the face of the Moon; it really lends a 3D aspect to it all. And if the Moon moves deep enough into the umbra there may be some color that develops.

Penumbral lunar eclipses are an exercise in chasing ghosts, as that describes perfectly the penumbra – ghost-like. If the eclipse is deep into the penumbra shadow it may show itself visually.

Photographing Lunar Eclipses

Your photographic setup for a lunar eclipse is the exact same as for a solar eclipse except you do not need to include a filter or use eclipse glasses. You would need to do the same type of shipboard preparing, and make up your eclipse plan. Lunar eclipses can go for hours, and they are really fun and relaxing to watch.

Total Lunar Eclipse

As the penumbra begins to cross the bright Full Moon you may begin to see a very slight and light gray shading. As the eclipse progresses, the dark umbra will begin to appear. The full Moon will gradually get darker and start to take on some reddish-orange-copper color.

As totality nears the stars start to come out and provide a nice backdrop. At totality the full Moon can exhibit a wide variety of colors and levels of brightness, as each eclipse is different (Figs. 10.17, 10.18, 10.19, and 10.20).

Fig. 10.17

Object viewed: Partial phase eclipse. (Image by the author)

Ship: Azamara Journey

Lens used: 28–300 mm at 28 mm f/3.5

ISO : 5000

Exposure: 5 seconds

Comment: The clouds break as a partial eclipse is underway in the Southern Ocean

Fig. 10.18

Objects viewed: Stars and totally eclipsed Moon (Image by the author)

Ship: Azamara Journey

Lens used: 28–300 mm at 28 mm f/3.5

ISO: 5000

Exposure: 5 seconds

Comment: Totality in the Southern Ocean with background stars

Fig. 10.19

Object viewed: Totality in the Southern Ocean. (Image by the author)

Ship: Azamara Journey

Lens used: 28–300 mm at 300 mm f/5.6

ISO: 8000

Exposure: 1/10 second

Comment: Shooting at 300 mm it was necessary to cut down the exposure time to offset the wind (it was very active at 40 knots across the top deck) and the movement of the Moon and ship. An increased ISO would allow increased shutter speed

Fig. 10.20

Object viewed: Copper penny colored totality (Image by the author)

Ship: Zuiderdam

Lens used: 55–200 mm f/3.5–5.6 200 mm f/5.6 DX

ISO: 3200

Exposure: 1/4 second

Comment: You can see the difference in the coloring of totality (Fig. 10.19). Wind was not a factor either

Partial Lunar Eclipses

These eclipses can hardly cover the Moon with the umbra or be a deep eclipse. Try the partial eclipse settings used and SAAS.

Penumbral Lunar Eclipse

The penumbra graces all eclipses at their beginning and end. Sometimes the Moon will experience just a penumbral eclipse. See if you can photograph the penumbra. You can use settings for the full Moon and SAAS.

Seeing eclipses at sea are pretty rare occurrences. Use the tips in this chapter to take pictures on land when eclipses occur. That will help prepare you for an eclipse at sea and will be easier to accomplish!

© Springer Nature Switzerland AG 2018

Gregory I. RedfernCruise Ship Astronomy and AstrophotographyThe Patrick Moore Practical Astronomy Serieshttps://doi.org/10.1007/978-3-030-00958-8_11

11. Spotting the International Space Station and Other Satellites

Gregory I. Redfern1  

(1)

NASA JPL Solar System Ambassador, Ruckersville, VA, USA

Gregory I. Redfern

Spotting Satellites

A lot of people do not realize that they can see the International Space Station (ISS) with their own eyes. To watch the ISS is to visualize one million pounds of space hardware the size of a football field traveling at 17,500 miles per hour about 250 miles up, carrying 3, 6, or 9 humans. Oh, and ISS has done so continuously for seventeen years!

It is bright – so bright as to qualify at times as the third or fourth brightest object in the night sky after the Moon, Venus, Jupiter. This excludes when Mars is at its brightest. There are times, though, when the ISS is brighter than Jupiter. The brightness of the ISS and the path it will follow across the sky depends on the circumstances of the sighting pass. Each pass will be different.

The reason why each pass of the ISS (and any satellite) is so variable for any given location on Earth is simple – it is orbiting Earth, a planet that is rotating on its axis and orbiting the Sun. It is possible to see multiple passes of the ISS and some other satellites during a night of observing.

Let’s take a look at ISS first, as this is the most prominent satellite to be seen, excluding the flash sightings of Iridium satellites, which we’ll cover later.

If the ISS remains low on the horizon for the entire pass it will be about as bright as Vega, which is not too shabby. If the pass will be high in the sky and perhaps even directly overhead, then the ISS will continuously become brighter as it gets higher and higher above the horizon. If you are lucky enough to see the ISS at the zenith (directly overhead at 90 degrees above the horizon), it is really bright.

When the ISS is making its pass for your location it will rise above the horizon in a given direction (azimuth), fly a path across your sky to a certain altitude above the horizon and then disappear either into Earth’s shadow or over the horizon at a given azimuth. Watching the ISS appear and then fade is always a treat because of the brightness and color variations.

When the ISS is low on the horizon – either appearing or disappearing – it is at its farthest distance. Hence, the dimmer brightness and possible color variations due to being deep in Earth’s atmosphere. You won’t see “twinkling,” like we do for a star or planet low on the horizon, because the ISS and other satellites are not a point source but have a definite, albeit small, angular diameter.

As the ISS gets higher in the sky the distance between you and the station is decreasing until it reaches the highest point of the pass. This will be its closest point to you and maximum brightness. If directly overhead, which is the closest the ISS can ever be to you, it is about 250 miles. After closest approach the ISS will begin to increase its distance from you and decrease in brightness until it fades out of sight.

Knowing when the ISS will be visible for your location is pretty easy to do. There are a number of ways you can go about doing this while ashore. You can sign up with NASA or several other websites to get personal text or email messages as to the visibility of the ISS from your own home or other location. See the Appendix at the end of this book.

Although NASA provides notification only for the ISS other websites can provide sighting information on the ISS and all of the other satellites in the sky. Heavens Above is one such website. Like NASA’s “Spot the Station,” it is free for you to follow the very busy comings and goings above our heads.

Your astronomical software probably provides the same capability as these online websites do. You would have to define your location and settings preference as to satellite magnitude limits and method of notification. The main advantage to using your software is that when you are at sea it does not need access to the Internet/Wi-Fi to function, while the websites do.

To determine what satellites will be visible for any given time and location all you have to do is input your location – at sea this will be latitude and longitude, unless you happen to be near a major city – along with the time zone the ship is in. This information can be obtained off of the ship’s navigation channel or by asking someone at the front desk. Once you input this information make sure you have activated the “Satellites” feature of your software according to the instructions. You probably can get a listing of what will be visible for a given time period and perhaps an actual audio alert that says a satellite is rising.

Astro Tip

Your satellite feature may be part of the ‘Solar System’ in your software . You want to make sure that the “minor body orbit data’ is up to date before you sail, as you may not be able to get Wi-Fi to do so on the ship. If you do have such access it would be a good idea to update each night before you plan to use it, as the world of satellites is always changing.

Satellites other than the Hubble Space Telescope and the ISS are for the most part much higher above Earth and therefore much dimmer. On any clear night, when the bright Moon is absent, you can see numerous satellites moving all across the sky. They are pretty easy to distinguish from aircraft as they will have no blinking or multiple lights visible. Even aircraft at 40,000 feet at night can be identified due to their appearance.

One exception to satellite brightness versus distance from Earth is the Iridium constellation of communication satellites. Some of these satellites in their orbits can cause what is known as an Iridium flare, which is sunlight reflecting off of the antennas of the spacecraft. This can produce a seconds-long flare up to –8th magnitude and outshines everything but the Moon.

These events are predictable and tracked for your location using your astronomical software and the Heavens Above website . Once again the caveat becomes if you have WiFi on the ship. You do have to input the location to see if there are any upcoming events. Your astronomical software probably won’t tell you if an Iridium satellite is going to flare, but it will identify it in a constellation so you can watch and see what happens.

These super bright Iridium flares will probably be no more by the end of 2018, as the existing Iridium satellite constellation is being replaced by smaller and less reflective spacecraft. Starting in 2017, as each new Iridium spacecraft was launched into orbit and placed into operation the old spacecraft was being de-orbited. So enjoy them if you still can!

Photographing the ISS and Satellites

Photographing ISS and satellites is tricky at sea because of the motion of the ship. Even when it is a perfectly calm sea, which is a pretty rare occurrence, the ship is still moving through the water, and the ISS or satellite is moving through the sky at a fairly rapid rate. A tripod is essential or ship bracing, as you have to eliminate as much motion as possible. A shutter release or shutter delay is required as well. You can try taking a time exposure using a wide angle or medium focus lens and see how it turns out. SAAS.

Shown in Fig. 11.1 is a short time exposure of the ISS aboard Holland America’s Prinsendam . You can see how bright the ISS is. This shot was taken in the hours before dawn in the Atlantic.

Fig. 11.1

Object viewed: The ISS. (Image by the author)

Ship: Prinsendam

Lens used: 35 mm f/1.4

ISO : 3200

Exposure: 10 seconds

Comment: EKG ISS, showing the effect of combined motion

If you reduce your exposure time to 1 second this greatly reduces and may totally eliminate the motion effect, as you can see in this photograph in Fig. 11.2 of the ISS taken in the Indian Ocean aboard Azamara Quest .

Fig. 11.2

Object viewed: ISS. (Image by the author)

Ship: Azamara Quest

Lens used: 35 mm f/1.4

ISO : 3200

Exposure: 1 second

Comment: A much better exposure of the ISS

Observing satellites at sea is certainly possible, but they are difficult to photograph, as they are pretty dim, and sea conditions aren’t conducive to it. But if you want to try use a high ISO – at least 3200 up to 8000 or higher – with a fast wide-angle lens and a time exposure based upon sea conditions.

© Springer Nature Switzerland AG 2018

Gregory I. RedfernCruise Ship Astronomy and AstrophotographyThe Patrick Moore Practical Astronomy Serieshttps://doi.org/10.1007/978-3-030-00958-8_12

12. Asteroids and Comets, Meteor Showers, Fireballs and Bolides

Gregory I. Redfern1 

(1)

NASA JPL Solar System Ambassador, Ruckersville, VA, USA

Understanding Cosmic Debris

The Solar System is teeming with countless bits of cosmic debris, large and small. Some are left over from the formation of the Solar System  – asteroids and comets – 4.6 billion years ago, while others were created in subsequent collisions between these bodies and huge impacts on planets and moons. In this chapter we’ll explore asteroids and comets and how they are responsible for streaks of light, possibly even sounds, in the sky and rocks from space.

As you learned in Chap. 8 the birth of our Solar System resulted from collisions of ever larger bodies to form the planets and their moons. When all was said and done the Solar System, as we know it today, was the end result. Truth be told, we really do not know all there is to know about our own backyard, and new discoveries are being made all the time.

Sure, we have explored all of the classic nine planets by spacecraft and landed on other worlds, but the region between Mars and Jupiter – the main Asteroid Belt – and the dim outermost (we think) region of the Solar System – the spherical Oort Cloud that surrounds the Solar System, which is home to trillions of comets – are largely unexplored.

The main Asteroid Belt has millions of rocky asteroids (sometimes called minor planets) ranging in size from the largest, Vesta (329 miles across), to less than 33 feet across. Vesta and the largest asteroids are nearly spherical in shape, while most are expected to be irregularly shaped, as we have seen in our spacecraft missions. We have discovered asteroids that have small moons and binary and triple asteroid systems. They are ancient and pitted with impacts. They can rotate or tumble. The estimate of the total mass of the Asteroid Belt is less than that of our Moon. There is a lot of space between the asteroids, something that isn’t usually depicted in movies. All of our spacecraft headed to the outer Solar System have been able to safely pass through the Asteroid Belt.

Asteroids can collide with one another and be affected by the gravitational interaction with Jupiter and Mars. This can cause them to stray out of the Asteroid Belt and journey through the Solar System. Some of these find their way to the vicinity of Planet Earth to become near Earth asteroids (NEAs), which currently number over 18,000 and with more being discovered all the time.

In addition to asteroids, there are trillions of comets – “dirty snowballs” composed of frozen gases and ice, rock and dust – that can be miles across that are remnants of our Solar System’s formation, like asteroids. They exist in the far and very cold depths of the Solar System in two locations.

One grouping of comets is out beyond Neptune, in the neighborhood of Pluto, in an area called the Kuiper Belt, a disc-shaped region of the Solar System containing ancient icy bodies. Proposed by the famous planetary astronomer Gerard Kuiper (1905–1973), over 1,300 Kuiper Belt objects (KBOs) have been identified since the first KBO was discovered in 1992. Hundreds of thousands of KBOs are thought to be larger than 100 km or more in diameter, while trillions of comets roam the Kuiper Belt. KBOs are sometimes called Edgeworth-Kuiper Belt objects or transneptunian objects (TNOs).

Humanity will get its first up close and personal view of a KBO, 2014 MU69, also called Ultima Thule, on January 1, 2019. That’s when at a distance of 4 billion miles from Earth the New Horizons spacecraft does a flyby of the KBO. The Hubble Space Telescope discovered 2014 MU69 as part of a search for potential targets for New Horizons to explore after its wildly successful flyby of Pluto in July 2015. Planetary scientists are eagerly awaiting the results of this flyby to learn more about KBOs in this region of the Solar System. It will have taken thirteen years of flight time to get to this ancient body, and it may be a long time until humanity passes this way again.

The comets from the Kuiper Belt are known as short-period comets, as their orbits around the Sun take less than 200 years. These comets get perturbed gravitationally or possibly by collisions among themselves to begin their journey through the Solar System.

What is called the Oort Cloud also harbors comets that can be disrupted by the passing of a star, a molecular cloud or possibly cometary collisions. The Oort Cloud is very distant from the Sun, perhaps as much as 5 billion miles to the inner shell to well over a light year or 9 trillion-plus miles to its outer shell. Our own Milky Way Galaxy can affect it as we orbit the galaxy.

When these comets are perturbed out of the Oort Cloud they begin a really long fall, primarily under the gravitational influence of the Sun, towards the inner Solar System. Their orbits around the Sun can take millions of years and thereby rightfully earn the term long-period comets.

As comets get closer to the Sun they begin to undergo a dramatic transformation. The heat from the Sun begins to act upon the nucleus, or solid body, of the comet. This heat becomes sufficient to cause the frozen ices and gases of the nucleus to sublimate, or go directly from a frozen to a gaseous state. This also releases dust and rock fragments from the nucleus.

A coma, comprised of these gases, ices and dust forms a large opaque atmosphere around the nucleus. The Sun’s solar wind and solar radiation pressure blow material away from the coma to create two tails. One tail is made of dust and is yellow in color while the other is made of gas ions and is usually blue or green in color. The particles in the dust tail are about the size of cigarette smoke particles (small and fluffy) and are easily affected by the pressure exerted on them by sunlight. This can cause a grand sweeping tail due to the comet’s orbital motion. The gas ion tail forms when ultraviolet light from the Sun ionizes the gas, which then interacts with the solar wind to push the tail directly away from the Sun.

Comet tails can be millions of miles long and look very, very majestic in the sky. It is no wonder that the ancients called them comets, which translates from Latin into “longhair.” The ancients feared comets, as they were seen as portents of doom. That amazingly has carried forth into the twentieth century, as in the late 1990’s a cult committed mass suicide in order to join the “mother ship” their leader said resided in Comet Hale Bopp – a prominent comet widely seen in the Northern Hemisphere.

As comets pass through the Solar System they can be gravitationally captured by the larger outer planets. We have seen this in the Jupiter family of comets. Comets (and asteroids) can also impact them. We have seen this happen to Jupiter most spectacularly in July 1994 with Comet Shoemaker-Levy 9 (SL-9). The world watched 21 cometary fragments in succession impact the Jovian atmosphere, unleashing huge amounts of energy and creating Earth-sized smoke clouds. Amateur astronomers have photographically captured additional impacts into Jupiter’s atmosphere, although it cannot be positively determined what type of body caused them.

Seeing the SL-9 impacts happen in real time moved the U. S. Congress to annually appropriate money to NASA for the express purpose of finding such impact hazards. Prior to SL-9 the number of professional astronomers worldwide looking for impact hazards in the form of comets and asteroids was smaller than the night shift at a famous hamburger chain restaurant. NASA’s efforts have increased and improved since SL-9, and today there are far more astronomers, telescopes and spacecraft looking for asteroids and comets.

NASA keeps watch on all known asteroids and comets, oversees efforts to discover new ones and is responsible for planetary defense. Collectively asteroids and comets that come near the Earth are called near Earth objects (NEOs), as mentioned earlier. NASA and other organizations such as SPACEWATCH®, a network of telescopes searching the skies, collectively accomplish these tasks through several spacecraft missions, worldwide cooperation and help of the Jet Propulsion Laboratory’s (JPL) Center for NEO Studies (CNEOS). CNEOS computes high-precision orbits for NEOs in support of NASA’s Planetary Defense Coordination Office. The orbital solutions are used to predict NEO close approaches to Earth in order to produce comprehensive assessments of NEO impact probabilities over the next century. It’s a big and never ending job that has high stakes for the long-term survival of humanity, as you shall see.

Space is a big place, and it is not unusual to find asteroids after they have passed their closest to Earth. Some asteroids we never see coming until they make their presence known as bolides. Bolides are asteroids or comets or fragments of them that enter Earth’s atmosphere and explode. If the incoming bolide is large enough it can survive the passage through Earth’s atmosphere and impact the planet, making an impact crater. As of August 2018 there were 190 confirmed impact craters on Earth. Remember that 71% of Earth is covered by water, which means that there are a lot more on the bottom of the world’s oceans.

Smaller bolides that are made up of rock, nickel-iron or a combination of the two can also produce meteorites when they explode. Meteorites have fallen to Earth that originated from the Moon and Mars as a result of the giant impacts on those bodies that blew large amounts of material out into space. As of June 2018 there were currently 210 known Martian meteorites, 344 lunar meteorites and 59,258 classified meteorites, with more being found and classified regularly.

There have been several modern-day instances of an asteroid bolide exploding over a populated area and dropping hundreds if not thousands of meteorites on the startled citizens. Murchison, Australia; Holbrook, Arizona; and Forest Park, Illinois all have amazing stories about the day (and night) when stones rained from the sky. Cars, houses and even a ship at sea have been hit by falling meteorites, but so far only one verifiable instance of a human being hit and badly bruised by a space rock has happened. The number of hoaxes regarding meteorites is endless, as are the doomsday headlines regarding asteroids.

On a far more menacing note two bolides took place over Russia that have definitely defined the threat from smaller asteroids. On June 30, 1908, a bolide detonated in a probable airburst with the destructive force equivalent to at least 10 to 15 million tons of TNT over Tunguska, Siberia. Over 2000 sq. km and an estimated 80 million trees were destroyed, but with no known human fatalities. The shockwave went around the planet three times, and Londoners were able to read their newspapers at midnight by the light of sunlight reflected off of the countless debris particles in Earth’s atmosphere.

No impact crater or meteorites have been found from the Tunguska bolide event. In all probability an asteroid the size of a football field weighing 220 million tons caused this event. If this bolide had exploded over a modern city it would have destroyed it and killed the majority of its population. Estimates of a Tunguska event over New York City, New York, predicts over 2.5 million deaths alone. Astronomers calculate an event of this magnitude occurs every 500 years.

On February 15, 2013, at 9:20 a.m. local time in the area of Chelyabinsk, Russia, home to one million people, a bolide exploded with the force of 600,000 tons of TNT. Over 1600 people suffered cuts, bruises, retina burns and other injuries due to the shockwave and brilliant explosion. One million square meters of glass was broken, and several buildings suffered partial collapses, again due to the shockwaves from the bolide’s detonation 19 miles up.

Chelyabinsk rewrote the book on asteroid threat levels because beforehand it was thought that 65-foot asteroids were not that severe a threat. Chelyabinsk changed all that, as it was the most studied meteoritic event in history. Abundant security and dash cam video, satellite imagery and recovery of thousands of meteorites made it possible to study this event like no other. Chelyabinsk was a stony asteroid from the main Asteroid Belt, where there are millions more like it. We never saw it coming….

Ironically the same day of the Chelyabinsk event a 98-foot wide asteroid named 2012 DA14 made a close approach to Earth, only about 17,200 miles from Earth’s surface. The two events were not related in any way, but what a coincidence!

Unfortunately the rate of asteroid discoveries is not very high, compared to the million or more that are believed to be of possible threat to humanity. At the current rate of about 1000 discoveries a year it will take about a thousand years to find them all. To be blunt, we have to do better – Tunguska and Chelyabinsk have shown us that we must. There are efforts underway to do so.

In 2014 a group of scientific and spaceflight luminaries got together to put the asteroid threat and what we can do about it in the eye of the worldwide public. They formed “Asteroidday.org” and held a press conference simultaneously in London and San Francisco on December 3, 2014, to announce the launch of Asteroid Day. Held annually on June 30 to commemorate the Tunguska bolide, Asteroid Day marks the anniversary with worldwide events. Be sure to see what events may be in your area.

As a final note on the threat posed to humanity by asteroid and comet impacts we are here because the dinosaurs were wiped out 65 million years ago by an impact event. The whole planet suffered as a result of this 6-mile wide or so impactor that unleashed the destructive power of an estimated 100 million megatons of TNT. Life clawed its way back from near extinction, as over 75% of all life on land and in the seas was gone.

We see the proof of this asteroid or comet impact in the K-T boundary that is in the geological record everywhere on the planet and the 180-km-wide Chicxulub Crater that is located in the Yucatan Peninsula. Our planet has undergone several major extinction events, and we certainly do not want to do so again.

Humanity can currently only detect the threat, and as you have read not nearly as efficiently as we need to. To deflect or destroy the threat we need technology and spaceflight capability to do so. All the justification we need lies in this phrase: “The dinosaurs are dead because they didn’t have telescopes or a space program.”

Photographing Asteroids and Comets

Your astronomical software probably provides information on asteroids and comets. You would have to define your location and settings preference as to asteroid and comet magnitude limits.

To determine what asteroids and comets will be visible for any given time and location all you have to do is input your location – at sea this will be latitude and longitude unless you happen to be near a major city – along with the time zone the ship is in. This information can be obtained off of the ship’s navigation channel or by asking the front desk. Once you input this information make sure you have activated the “Asteroids” and “Comets” feature of your software according to the instructions. You probably can get a listing of what will be visible for a given time period.

Astro Tip

Your asteroid and comet feature may be part of the ‘Solar System’ section. You want to make sure that the “minor body orbit data’ is up to date before you sail, as you may not be able to get the Internet on the ship. If you do have such access it would be a good idea to update each night before you plan to use it.

At sea we can observe and photograph comets and asteroids if they are bright enough, but this is usually not the case. At any given time there are a number of asteroids and comets in the sky, but they are below the threshold of being observable with the unaided eye and photographed at sea. The brighter asteroids Ceres and Vesta can be seen with binoculars when they are closest to Earth and photographed as part of a star field.

Using your software you can determine the position of Ceres and Vesta and where on the ship would be best to see and photograph them. A 35-mm to 50-mm lens mounted on a tripod would be best to use, as it would give you a good field of view to search for the asteroid among the stars in the photograph. Studying the stars around the asteroid in the display from your software will give you visual references as to where to point your camera. You don’t have to be dead-on precise, but you have to be close enough to capture the asteroid in the star field.

You would take a 2- to 3-second exposure at ISO 3200 if the Moon were out of the sky or not too bright. Then you have to look at the star field in your picture and compare it to the star field in your software to identify the asteroid. If you really want to get fancy, take a second exposure a night or two later, which will show the asteroid’s movement in the sky, which is pretty cool to see.

Viewing Comets and Meteor Showers

Comets are a different animal. They are always out there but usually too faint to see or photograph. This is where you have to stay informed as to what is happening in the night sky, as comet discoveries are announced in the journals and social media if they are bright enough. The northern hemisphere is way overdue for a spectacular comet, while the southern hemisphere has had some amazing comets the past few years.

If a bright comet is present in the sky it would be the same procedure as photographing an asteroid except that the comet will be larger and brighter than a star-like asteroid. If we are really lucky a comet will appear that has a visible tail. Comets can appear near dusk and dawn or at night. There have been rare occasions when they were visible in daylight! If that were to happen everyone in the world would know about it and being at sea would be no exception.

Moving on to a lighter topic – meteors and meteor showers. Have you ever looked up and seen a “shooting” or “falling” star? Did you make a wish upon a falling star? Did your wish come true? What you observed was a meteor – an incoming bit of an asteroid or comet that vaporized and also ionized the column of air it passed through in our atmosphere. Meteors happen 24 hours a day and night all over the planet. It has been estimated that at least 200,000 pounds of meteoritic material falls to Earth daily, although some estimates are much lower or higher.

Your own roof acts as a collector of this material. Try this little experiment. After a dry spell of no rain followed by a rain shower take a magnet out to where your roof’s gutters dump out. Run the magnet through the debris and see if anything sticks. Unless you have metallic components to your roof shingle or live in a very urban setting, where air pollution would contribute to your sample, you may have some micrometeorites in your possession. It takes actual testing to determine if you have a micrometeorite, but it is fun to prospect for them. See the Suggested Readings section for this chapter.

The two-year METEOR mission aboard the International Space Station (ISS) may give us a better estimate as to the amount and composition of meteors. METEOR monitored meteor activity with a high definition video camera during night-time periods aboard the ISS; for one year it visually monitored the fall of meteors, while for the second year it took spectra of the meteors to determine their composition. The METEOR mission was scheduled to end in July 2018 with results to follow. This might give us the data necessary for an accurate determination of the number of meteors, their composition and perhaps the amount of meteoritic dust generated.

The Solar System is teeming with dust and debris from comets, asteroids and impacts. So on any clear night we can see sporadic or random meteors. But there are specific times of the year when Earth passes through a concentrated debris stream left behind from the passage of comets and one asteroid in particular, 3200 Phaethon, in their annual orbits around the Sun.

When this happens we see a meteor shower. There are eleven major meteor showers, annually with a number of minor meteor showers, each named for the constellation from which the meteors seem to come. Most of these favor Northern Hemisphere observers, but there are some for the Southern Hemisphere as well. The actual point in the sky where the meteors can be traced back to is called the radiant. Each shower has a predicted time of maximum activity and characteristics such as estimated number of meteors per hour, speed and visual appearance.

The August Perseids is the most popular meteor shower, as it occurs during the warm summer months, when families are on vacation, people are camping and a lot of them enjoy the night sky. From a dark sky site with no Moon the Perseids can put on quite a sky show, with upwards of 60 meteors or more per hour.

Another popular meteor shower is the Geminids in December, which is the only meteor shower caused by an asteroid. The Geminids produce a number of fireballs – meteors brighter than Venus – thought to occur because the Geminid meteors are of a more solid composition than cometary material.

Consulting references such as the Observer’s Handbook and Sky & Telescope will provide up to date information for each shower.

The best place to see a meteor shower is in a dark sky site with an unobstructed view of the whole sky – in other words, at sea. If your cruise coincides with the occurrence of a meteor shower – and no Moon interference – by all means you should go up on deck and watch it.

You would want to determine the location of the radiant (constellation) relative to the ship’s course and go to the highest deck location that has the best view with minimal light. You do not have to look directly at the radiant, as meteors will appear across the sky during a meteor shower. The optimal plan is to get a deck chair that faces the general direction of the radiant and kick back, relax and enjoy the view.

Ship Tip

If there are some light sources around your viewing area try wearing a hooded garment and pull it up to block the light. You’ll be amazed how improved the view becomes by blocking out light.

Photographing a Meteor Shower and Meteors

On land it is very easy to try and capture a shooting star. Just mount your camera with the widest angle lens you have at its maximum aperture (wide open) on a tripod, point it to an area of the sky near the radiant and take a time exposure.

Where you point your camera is directly akin to where you put your fishing line in the water. Try to pick a point away from the radiant to cover as much sky as possible. Then watch for the shower; there may be a perceived preference as to where the meteors are coming from. Like fishing, patience and luck is the name of the game.

How long you expose depends on how much light pollution your observing site has. If it is dark you can get away with exposures measured in minutes; if you have light pollution you are talking probably 30 seconds. The ISO should be 3200 or higher, depending on the light pollution. Take a few test shots to see what your optimum combination of time and ISO are. You want a fairly dark background that shows the stars; the stars can be trailed, as a meteor will show up as a streak across the frame.

Once you know your optimal shooting parameters you can set up a sequence of shots by referring to your camera manual on how to do so.

At sea, this is a far different story. The motion of the ship determines everything. If the ship is experiencing motion in the ocean it may be a visual-only experience. If the ship is steady and not too active in her movement then it may be worth a shot to see what you get.

You will probably have a dark sky with just ship lights to contend with, but they can be problematical. Finding the area with the least lights and best view of the meteor shower’s radiant and surrounding sky is your first step, and then mounting the lens hood is your second. You can also try standing near your lens to block out light, but this can be tedious over the length of a meteor shower.

Taking test shots to determine the quality of the resulting photograph is necessary. You may be able to get 30-second exposures with a 14-mm lens on a steady ship at night. Even if the star trails in the long exposure photograph show some motion other than their customary trailing, what we call “EKG Motion,” a meteor that is bright enough will still show up as a straight streak across the frame.

If you want to go “fishing” for sporadic meteors, fireballs and bolides you can do so any clear night. Just follow the previous setup and shoot to your heart’s desire. You can lay back on deck in a lounge chair watching the sky while your camera does all the work, but you will have to go through them later to see if you caught one – which is fun to do, by the way. If you see a fireball or bolide you will know it. Even if you are not looking directly at the bolide event you will know about it due to the ship lighting up or the sound of the bolide exploding. Those get the heart pumping when they happen (Fig. 12.1).

Fig. 12.1

Object viewed: Milky Way meteor. (Image by the author)

Ship: Azamara Quest

Lens used: 50 mm f/1.4

ISO : 6400

Exposure: 4 seconds

Comment: A rare at-sea meteor picture, a sporadic one, caught while photographing the Milky Way. Notice how the meteor streak is straight, while the stars have EKG

Good hunting!

© Springer Nature Switzerland AG 2018

Gregory I. RedfernCruise Ship Astronomy and AstrophotographyThe Patrick Moore Practical Astronomy Serieshttps://doi.org/10.1007/978-3-030-00958-8_13

13. Auroras and Other Glows in the Sea and Sky

Gregory I. Redfern1 

(1)

NASA JPL Solar System Ambassador, Ruckersville, VA, USA

In this, our last chapter on astronomical objects, we will look at what glows in the sky and in the sea. Some of the phenomena in this chapter take place high and low in Earth’s atmosphere, while one comes from space and another is in the sea. If the Moon is bright in the sky, some of them will be harder to see, so you will have to keep that in mind when you go hunting for these wonderful visual treats above and below your ship. Good luck and clear, dark skies!

Auroras

The most recognizable and famous of sky glow phenomena are auroras. These ghostly apparitions can appear in the Northern and Southern Hemispheres, respectively, as the aurora borealis and aurora australis. They are caused by the interaction of Earth’s magnetic field and high atmosphere with charged particles from the Sun – the solar wind . They can be seen year-round from high latitudes in both hemispheres, although occasionally a large outburst from the Sun can push the aurora to lower latitudes.

The National Oceanographic and Atmospheric Administration (NOAA) constantly monitors space weather , which is variations in the space environment between the Sun and Earth, along with the rest of the Solar System. These variations can affect technologies in space and on Earth. We depend heavily on these technologies, which include electrical power distribution, radio and TV communications, GPS, airline routes, spacecraft health and astronaut safety to name a few. NOAA issues constant updates and warning notices on its space weather website.

Space weather is primarily driven by storm events on the Sun that include coronal mass ejections, solar flares, solar particle events and the solar wind . These can vary as the Sun goes through its on-average eleven-year sunspot cycle that is measured from when the Sun has minimal or no sunspots – solar minimum – to when the Sun has the observed maximum of sunspots – solar maximum. The Sun is typically more active with solar storm events at or near solar maximum, and can produce more auroras.

There is a whole tourism industry on sea and land regarding seeing the aurora. Do an Internet search and you will find a number of travel companies, including cruise lines, that offer excursions dedicated to seeing the aurora. If seeing the aurora is your primary goal you might want to check out these cruise opportunities.

If you want to look for the aurora on your own cruise, one really important resource is NOAA’s Aurora 30 Minute Forecast website, which is included in the Suggested Reading section for this chapter. It provides Northern and Southern Hemisphere aurora forecasts that can help you determine if you will have possible aurora sighting opportunities. NOAA also has a 3 day aurora forecast website that is up and running though it is still being tested. There are a number of commercial and private aurora websites you can check out if you want to, but it is hard to beat NOAA.

If you are on an aurora dedicated cruise, the staff will do all the work and you get to sit back, relax and enjoy the sky view. If on your own you will need to have access to the Internet to hit NOAA’s website. Look at the 3-day forecast to see what is expected for your location, and if it looks good, follow up with the 30-minute forecast. The forecasts show a view centered on the poles that is color coded as to aurora visibility probabilities. It is easy to use, and if you are near the forecast zone it is worth getting out and taking a look (Fig. 13.1).

Fig. 13.1

Object viewed: Green aurora borealis. (Image by the author)

Ship: Azamara Quest

Lens used: 14 mm f/2.8

ISO : 2000

Exposure: 2.5 seconds

Comment: Bright green aurora with the Big and Little Dipper off the coast of Seward, AK

While viewing aurora you may see a bright purple filament that looks like an aurora but isn’t. Meet STEVE – Strong Thermal Emission Velocity Enhancement (Fig. 13.2). Although seen for decades by skywatchers and photographers it wasn’t until 2018 that scientists began to figure out what STEVE is – a fast moving stream of extremely hot particles that travels along different magnetic field lines than the aurora. Research coninues into this new aspect of chemical and physical processes in Earth’s upper atmosphere.Taking Aurora pictures is pretty straightforward, as you would determine where they are in the sky and then determine the best location on the ship to see them. You would want to use a tripod with a lens appropriate to the size of the aurora, which can be small or quite large in the sky. It can also be overhead or in the distance. Auroras can also be quite bright or dim, shimmering or moving. Your ISO should be about 2000 to start, and the Moon might complicate your composition. This is definitely a situation where you would want to try different lenses, exposures and ISO combinations to get your best results. SAAS.

Fig. 13.2

Green aurora borealis and STEVE. (Image bythe author)Ship: Star LegendLens used: 14 mm f/2.8ISO: 4000Exposure: 8 secondsComment: Bright green aurora and STEVE off the coast ofSeward, AK

Astrophoto Tip

When consulting the NOAA Aurora Forecast and it shows you are near the predicted aurora event try taking some exposures even if you cannot see the aurora. You would orient your camera so that it is pointing towards the direction of the aurora forecast – probably along the horizon towards your hemisphere’s pole, i.e., North or South, and with your widest angle lens take the maximum exposures your sea and sky conditions will allow.

You can actually photograph an aurora with a camera that you cannot see with your eyes. An aurora forecast alert may advise that an event is taking place near your location. Align your camera to the direction the event was predicted to be taking place and take some exposures. The aurorae will probably be dim, but your camera will likely have no trouble in picking it up.

Airglow

Airglow can be confused with the aurora, but it is an entirely different phenomenon and is due to Earth’s high atmosphere interacting with the Sun. Instead of the high-speed particles of the Solar Wind that cause the aurora, Airglow is caused by the daytime Sun’s ultraviolet light. This intense light ionizes electrons of oxygen and nitrogen atoms and molecules – knocking them off only to recombine with their host atoms at night. This releases energy in the form of different colors of light, including green, red, yellow and blue. The brightest light comes from excited oxygen atoms, which is green and the color our eyes are the most sensitive to.

Odds are you probably won’t see airglow with your unaided eyes, as it is rather faint and shows up best in time exposures of the night sky. Airglow can occur anywhere on the planet, another distinction from the aurora, and is a nightly event. Also, the appearance of airglow compared to the aurora is quite different, as it will be faint, ghostly bands as opposed to the curtains and waves that auroras typically form. Airglow also will be viewed best at primarily 10 to 15 degrees above the horizon, whereas auroras can be anywhere.

Airglow can be hard to see at sea being only 10 to 15 degrees above the horizon. You would need lengthy time exposures at sea above 30 seconds, which might affect being able to photograph airglow, although there do exist pictures of 30 seconds exposure revealing airglow. Longer exposures are usually taken through a telescope or a telephoto lens mounted on an equatorial mount. None of these setups would be suitable for capturing airglow in the photograph at sea for reasons we already discussed.

Your eyes have to be completely dark adapted, and the sky fairly clear and dark. At sea the atmosphere near the horizon can be hazy and saturated with sea spray, if the wind has been up, which would affect the clarity necessary to see the airglow.

If you want to try and photograph airglow find the darkest location on the ship on a night when ship motion is minimal. Because you will be concentrating your efforts near the horizon here is a ship tip you need to take into consideration (Fig. 13.3).

Fig. 13.3

Object viewed: Milky Way and Jupiter at opposition. (Image by the author)

Ship: Prinsendam

Lens used: 14 mm f/2.8

ISO : 3200

Exposure: 30 seconds

Comments: You can see the glow of light of the ship’s forward masthead light projected into the sky on the starboard side of the Prinsendam in this otherwise dark sky background

Ship Tip

The ship’s white navigational lights, deck lights, decorative lights and stack exhaust can throw light patterns into the night sky that can show up on your photographs. Exposures of 30 seconds with a 14-mm f/2.8, 5 seconds, a 35-mm f/1.4 and 3 seconds with my 50-mm f/1.4 reveal light in an otherwise dark sky background.

You may be able to see this with your unaided eye, but your time exposure will show it better. You will want to eliminate this source of light for trying to photograph the airglow, as it will probably be at the preferred distance above the horizon that the airglow is. This effect is most pronounced in the bow and forward section of the ship, near the white masthead lights. They project forward and slightly aft and are bright in order to be seen by other ships.

The deck lights and decorative lights project lower because they are lower than the masthead lights, so they shouldn’t interfere 10 to 15 degrees above the horizon (Fig. 13.4).

Fig. 13.4

Object viewed: Shipboard shadow (or X-File selfie). (Image by the author)

Ship: Star Pride

Lens used: 14 mm f/2.8

ISO : 3200

Exposure: 1 second

Comments: Deck and decorative lights project a shadow as well as the deck rails onto the ocean

Stack exhaust can be readily seen at night when the wind blows it into a light source. Believe me, this can mess up an otherwise good picture or add an “only at sea” persona to the picture, depending on how you want to look at it. You may have no choice but to photograph your object of interest as the author had to in the following photograph. The ship’s course and the wind were blowing stack exhaust into the south, so no matter where I went on the ship it was going to show up. I went as far forward as possible to “move” the exhaust as far to the left as I could (Fig. 13.5).

Fig. 13.5

Object viewed: MWG LMC Stack Exhaust. (Image by the author)

Ship: Name withheld

Lens used: 14 mm f/2.8

ISO : 5000

Exposure: 15 seconds

Comments: The Southern Hemisphere Milky Way and Large Magellanic Cloud with stack exhaust

You will be taking at least 30 seconds to minutes-long time exposure, so a tripod is necessary. How long you can photograph depends on the ship’s motion. If she is steady start with a 30-second exposure and work your way up in perhaps 30-second intervals. Because airglow is faint you will want to keep camera motion to a minimum – to avoid “EKG motion” in your photograph – or you probably won’t pick up airglow.

Go with an ISO of 5000 to start with and a wide-angle lens up to a 35 mm. You want a lens that pulls in some detail along with sky coverage. A 14-mm might not be able to pull in sufficient detail of such a faint and wide area event such as airglow, but if that is all you have, try it. A 50-mm might be too confined in coverage to give you the best chance at picking up airglow, but once again if that is all you have, try it.

Try shooting a sequence of pictures and go back to your stateroom to use your computer to look at them, as your camera view may not be bright and large enough to show airglow. In processing your photographs you will want to experiment with exposure, brilliance and contrast to eke out faint details. If you got them, great; if not, decide if you want to try again.

NLCs

Another type of high atmosphere phenomenon is the noctilucent cloud (NLC) – or “night shining cloud.” If your cruise takes you to 45 to 65 degrees north or south latitude from May through August for the Northern Hemisphere and from November through February for the Southern Hemisphere, you may be in luck to see these beautiful blue-white or colorless clouds (Fig. 13.6).

Fig. 13.6

Object viewed: Noctilucent cloud. (Image by the author)

Ship: Azamara Pursuit

Lens used: 28–300 mm at 78 mm f/5.0

ISO : 2000

Exposure: 1 second

Comment: Through a break in the Iceland clouds the electric blue of NLCs shines through

NLCs appear about 90 minutes to two hours after sunset or before sunrise in the sky, where the Sun is setting or rising. They can be just above the horizon or higher up in the sky. Although the Sun is not visible for you, it is still visible at the 50+ miles altitude where the NLCs are located and illuminates them. This altitude makes NLCs Earth’s highest clouds.

NLCs are ice crystals that form on meteoritic dust (meteor smoke) in the mesopause. Of course this ties in to our discussion in the previous chapter about asteroids, comets and meteors. They are quite spectacular, and the astronauts on the International Space Station have seen them regularly. NASA’s Aeronomy of Ice in the Mesosphere (AIM) satellite mission has been studying them from space since 2007 and is slated to do so until September 2023.

If you are at sea in the latitude range and time frame for NLCs it is worth going up on deck before sunrise and after sunset to look for these clouds. They can take on a variety of appearances. Binoculars are said to help, as they make the NLCs appear sharper and therefore more distinct from other clouds.

Your photographic setup will be the same as for the aurora and airglow. The NLCs will be much brighter than the airglow and will occur at a time – sunrise and sunset – when the aurora may be visible as well, but the clouds will not be as bright as they would be in total darkness. NLCs and aurora have been photographed together, so be on the lookout for them as well.

You will need to determine the ship’s course compared to east or west, so you can pick out your location on deck. You also want to get out on deck at least 30 minutes before your predicted start time for the NLCs so you can set up. Minimizing the effects of lighting getting into your camera’s view is crucial, as you want as much sky as possible.

Because you will be shooting before dawn and after sunset the sky will be brightening or getting darker. You probably do not need a high ISO for either, so start with 800 to 1000 and a shutter speed in line with your sky brightness. The NLCs, if they are present, will be fairly bright, even those low on the horizon. You may be able to shoot handheld, but it is a better idea to have the tripod or ship bracing as a backup for longer exposures if necessary.

Remember, the NLCs are way up there, and they have their own distinct color, appearance and location/time preferences. These factors should help you find, photograph and identify them.

The Zodiacal Light

Next up in our parade of sky and sea glows is the zodiacal light, also known as the “false dawn” or “false dusk.” The zodiacal light is well named because for two weeks or more twice a year its ghostly light – similar to the brightness of the Milky Way at sea – permeates the constellations of the zodiac that accompany the Sun along the ecliptic (the annual path of the Sun in the sky). Seen at either deep twilight before dawn and after dusk, the zodiacal light usually takes the form of an elongated shape, described as pyramidal or conical, that looms up wide from the horizon and tapers off as it gets higher to an actual tip. It is visible only in dark, moonless and clear skies about one to two hours before sunrise or after sunset.

The zodiacal light can be seen in both hemispheres. When and where you look is determined by when you are on cruise and your ship’s position. If you are near the equator at the prime viewing times, you might be able to see both zodiacal light occurrences at dawn and dusk – it would be worth looking.

Otherwise here are the best times to be on the lookout for the zodiacal light:

Late February through early May, with the peak usually centering on the March equinox:

Northern Hemisphere

Evening (W) deep twilight

Southern Hemisphere

Morning (E) deep twilight

Late August through early November, with the peak usually centering on the September equinox:

Northern Hemisphere

Morning (E) deep twilight

Southern Hemisphere

Evening (W) deep twilight

The zodiacal light is pretty easy to spot at sea if the horizon is clear, and not hazy or cloudy. Your eyes must be fully dark adapted, and your chances are best if you are clear of any shipboard lighting. It doesn’t take much light to ruin your chances of seeing the zodiacal light.

The best views are generally when the ship is heading either directly towards or away from the east or west horizon where the zodiacal light is present, as you will see in the following astropics. That way you have either a bow or stern view, which also generally has the least lighting (Fig. 13.7).

Fig. 13.7

Object viewed: Zodiacal light at dawn. (Image by the author)

Ship: Amsterdam

Lens used: 14 mm f/2.8

ISO : 3200

Exposure: 15 seconds

Comment: Even with the ship’s motion, as seen in the star trails, the zodiacal light is still captured in the shot. Note the lack of ship lighting on the stern. The wake is illuminated somewhat

This white specter is caused not by our atmosphere, as it once was thought, but by sunlight reflecting off of the countless dust grains roaming the inner Solar System from near the Sun, where they are densest (and brightest), out to beyond Mars in the plane of the ecliptic. Dust left over from the formation of our Solar System, debris from passing comets and asteroids, plus debris propelled into space from impacts all make up this flotsam of the Solar System.

Once again your camera setup will be the same as for the previous phenomena in this chapter. You will need to determine the ship’s course compared to east or west so you can pick out your location on deck. You also want to get out on deck at least 30 minutes before your predicted start time for the zodiacal light so your eyes get dark adapted. Minimizing the effects of lighting is crucial, as you need to get as dark a view as possible.

ISO will be high; start at 3200 and see how it compares to 5000. Go with your widest angle lens to start with and limit to fast 14-mm or 35-mm lenses to get the best coverage with good detail. Exposures will be determined by your lens selection and ship motion.

Just like airglow shoot a sequence of pictures and go back to your stateroom to use your computer to look at them, as your camera view may not be bright or large enough to show the zodiacal light. In processing your photographs you will want to experiment with exposure, brilliance and contrast to eke out faint details. If you got them, great; if not, decide if you want to try again.

If you are out looking for the zodiacal light there is more for you to be on the lookout for. Because the dust that causes the zodiacal light is in the ecliptic plane and covers such a huge area of the Solar System, it is possible to see this band of ghostly light across the sky. Called the zodiacal band, this light is a very faint but visible extension in very dark skies leading from the zodiacal light as the sky gets fully dark. It will follow the ecliptic, which your software should project as a line in the display of the sky.

At local midnight the gegenschein, or “counter glow,” can be visible in the ecliptic/zodiac constellations that are closest to the southern meridian. It appears as a subtle but distinct glow in the sky but requires a clear, dark and moonless night to see.

Your setup for photographing the zodiacal band and gegenschein will be the same as for photographing the zodiacal light, but your ISO may have to be even higher due to the zodiacal band and gegenschein being dimmer. If you are underway during the time period for the zodiacal light here are some suggestions.

If you see the zodiacal light, try for the zodiacal band even if you can’t see it. You may be able to photograph it with your camera. Consult your software to determine where in the sky the ecliptic is located among the stars. It will be tracing a west to east line in the sky.

Take a time exposure photograph of the ecliptic using a 14-mm (30-second exposure) or your widest angle lens with its maximum possible lens opening, before the stars start to trail, at ISO 3200 and then ISO 5000. If you can’t get the ecliptic in one frame, try taking sequence shots along the ecliptic. Assess your photographs using your computer. If you do not see any likely images of the zodiacal band call it a night. There will be other opportunities.

If you have a good sky – no Moon, clear and dark skies – at local midnight try for the gegenschein. Find a good location topside that faces the southern meridian and take a time exposure photograph using a 14-mm (30-second exposure) to 35-mm lens (6-second exposure) at ISO 3200 and then ISO 5000. You want to center your exposure on the constellation that is on the meridian, as that should be where the gegenschein is located. Assess your photographs using your computer. If you do not see any likely images of the gegenschein call it a night. There will be other opportunities.

We now progress from the dim and elusive to the bright and easy to see, if they are present. Our following phenomena take place in our atmosphere and are pretty common sights at sea.

Solar Phenomena

Before we start on this, let’s briefly review the safety concerns with observing daytime atmopsheric phenomena involving the Sun.

NEVER look at the Sun with your eyes or point your camera at the Sun, as permanent damage to both will occur!!

Use a large ship structure to completely block the Sun as was done in (Fig. 13.8). The Sun must be FULLY BLOCKED to be safe. NEVER try to take a photograph of these phenomena unless the Sun is completely blocked.

Do NOT look through your camera viewfinder to take a picture; use LIVE VIEW if available or just point your camera towards the phenomena you are trying to photograph while in the shadow, with the Sun completely blocked.

Read and print out the Internet sites related to atmopsheric phenomena involving the Sun, especially the safety notes, included in the Appendix of this chapter.

DO NOT attempt to view or photograph these phenomena unless you fully understand the procedures required to safely do so.

Fig. 13.8

Object viewed: Solar halo. (Image by the author)

Ship: Amsterdam

Lens used: 28 mm f/22 (28 mm to 300 mm)

ISO : 2000

Exposure: 1/2500 second

Comment: High ISO was due to not resetting from earlier night shots, probably not enough coffee before doing day work. It shows that just about any ISO can be used in the day and still work

To start we have solar halos, Sun dogs, lunar halos and Moon dogs. Around the world and at any time the Sun and the Moon can interact with high cirrus clouds and the countless millions of ice crystals they contain to produce these phenomena. As you can see in looking at the references in the Suggested Reading section there are a number of halos that can occur, but the most common one day or night is the 22-degree halo. This is what people see most often and think of when referring to a solar or Moon halo. It has a 22-degree radius, which makes it a pretty big structure and hard to miss.

The Sun or Moon “dogs” that can appear at the 3 and 9 o’clock positions of the 22-degree halo occur when sunlight or moonlight refracts through icy clouds containing hexagonal plate crystals aligned with their large, flat faces parallel to the ground.

With regard to the Sun, their technical term is parhelia (sing. parhelion), and they are often white but can be very colorful, looking like bright patches of rainbow with red on the inside toward the Sun (or Moon) and blue on the outside.

For the Moon these are called parselenae and, like lunar halos, are fainter to see than solar halos-dogs. They are best seen near full Moon, and they often appear colorless but can have some color to them.

If there are cirrus clouds around day or night you should be looking for them. But note that there can be other types of Sun/lunar halos besides the 22-degree halos, which are rare.

One last Sun, Moon and cloud interaction is called the corona. This is not the Sun’s corona we talked about in the chapter on eclipses, so it can be confusing terminology. A solar or lunar corona occurs when they are partially enshrouded by thin clouds containing water droplets, or small ice crystals that diffract the light just like rainbows do. They can be bright and colorful but smaller than halos (Figs. 13.8, 13.9, 13.10, and 13.11).

Fig. 13.9

Object viewed: Lunar halo/dogs. (Image by the author)

Lens used: 18 mm f/4 (18 mm to 55 mm)

ISO: 800

Exposure: 3.6 seconds

Comment: This was taken ashore. Faint lunar halo and bright Moon dogs are visible

Fig. 13.10

Object viewed: Rare pyramid lunar halo. (Image by the author)

Lens used: 14 mm f/2.8

ISO : 3200

Exposure: 2 seconds

Comment: This is a rare pyramid-shaped crystal halo. Notice the multiple halos. This picture was also taken ashore

Fig. 13.11

Object viewed: Lunar corona . (Image by the author)

Lens used: 28–300 mm at 210 mm f/5.6

ISO : 400

Exposure: 1/4 second

Comment: This land-based photo shows you how bright and colorful these can be. Easily distinguished from a halo

Photographing these phenomena is as different as night and day. Start with your widest angle lens if you are shooting the halo; for the corona you can go with a longer lens, since it is smaller in size and you can get close for detail.

Just a quick solar safety reminder: NEVER look at the Sun or point your camera at the Sun when attempting to take these photographs – protect your eyes and camera by blocking out the Sun.

For solar events you will have a bright sky, be in complete shadow due to completely blocking out the Sun for safety and trying to capture delicate and fainter details in the clouds. The good news is that this will be handheld only, as you will be shooting at a fast enough shutter speed to negate any motion by the ship. As to ISO it doesn’t have to very high; try 200, 400 and 800 for a start.

The trick is going to be getting the right exposure that brings out the halo/corona without your shot getting too overexposed. Try your camera’s “Auto” setting for exposure and f/stop for the ISO you are working with. Then take a picture and, based on results, go to ‘manual mode’ if need be. Manual mode really gives you total control over your camera. You can take a picture, assess and shoot again if need be – SAAS.

Shooting the Moon halo/corona may require a tripod. It depends on how bright the halo/corona is compared to the Moon. The Moon won’t be in shadow, like the Sun was by being completely blocked for safety, so it will dominate your picture. You don’t want a high ISO because the Moon is bright. Start with ISO 400 to 800. You are really going to have play with the exposure to coax the faint details out of the halo/corona. For the lunar halo you might want to take several seconds exposure. It’s like trying to photograph a ghostly apparition, while the corona only needed less than a second because it was so bright and colorful. SAAS.

Rainbows and Moonbows

Rainbows and moonbows can happen at sea just about any time there is rain and Sun or a bright Moon. They are always opposite the Sun and Moon. They are at their best when these two bodies are low in the sky, which makes the rainbow/moonbow appear higher in the sky.

They may be full, multiple, and arching or fragmented, or even come from the bottom of a cloud, as you will see. They get their color from the water drops in the rain refracting sunlight and moonlight. They can take on many appearances; see the Suggested Reading section to learn more about them. They are colorful and pretty, especially against the backdrop of the sea and sky. Rainbows at sea are often seen; moonbows are much rarer.

You can see and photograph a very special kind of rainbow when the ship’s bow is making a lot of sea spray due to waves and wind, and when the Sun’s angle is just right. This might also occur during a bright Moon. It is a variation of a sea spray bow, that is, a rainbow caused by sea spray rather than rain – what we call a wavebow.

When the ship is riding the waves with her bow digging in and making spray, go up on the main deck and check it out. Go forward to the bow on either the port or starboard side. The Sun needs to be out (check when the Moon is bright also) and sea spray coming off of the bow. The higher the Sun the better, as sunlight needs to clear the ship’s superstructure to interact with the sea spray (Figs. 13.12, 13.13, 13.14, and 13.15).

Fig. 13.12

Object viewed: Rainbow. (Image by the author)

Ship: Liberty of the Seas

Lens used: 55 mm f/8 (18 mm to 55 mm) DX

ISO : 200

Exposure: 1/250 second

Comment: A nice rainbow

Fig. 13.13

Object viewed: Rainbow from cloud. (Image by the author)

Ship: Grandeur of the Seas

Lens used: 35 mm f10 (18 mm to 55 mm) DX

ISO: 400

Exposure: 1/400 second

Comment: Haven’t seen this before or since, a rainbow from a cloud

Fig. 13.14

Object viewed: Double rainbow. (Image by the author)

Ship: Grandeur of the Seas

Lens used: 18 mm f/11 (18 mm to 55 mm) DX

ISO : 200

Exposure: 1/500 Second

Comment: A nice double rainbow seen with ship pulling into Bermuda

Fig. 13.15

Object viewed: Wavebow. (Image by the author)

Ship: Prinsendam

Lens used: 28 mm f/14 (28 mm to 300 mm)

ISO: 200

Exposure: 1/800 second

Comment: A pretty wavebow on the port bow

Once again we deal with night versus day in photographing our subjects. A wide angle is best for rainbows/moonbows so as to capture as much of their full splendor as possible. If you are dealing with fragments you might be able to zoom in for a close up. Use the same settings as in the last section to get a start.

For wavebows you will want a wide-angle lens, and make sure that you have a clear filter to put over your lens to protect it from sea spray. Nothing like dried salt crystals to make it an adventure to clean your lens!

Lightning at Sea

Lightning at sea is a pretty amazing, but dangerous, spectacle, even though ships are designed with lightning protection. Follow these safety rules.

NEVER go on deck when lightning is present or in the ship’s weather forecast.

Go on deck ONLY when:

Lightning is far in the distance;

No thunder is heard; and

Skies are clear overhead and all around the ship.

If thunder is heard while on deck IMMEDIATELY go below.

Remember, “When Thunder Roars, Go Indoors!” or go below, as we say at sea. More on lightning safety at sea is in the Appendix of this book for this chapter.

Lightning photographed at night is far more dramatic, especially if you are lucky enough to get some sky sights in the frame as well. The sky at night with a full or bright Moon, lightning, sea and clouds will offer a colorful panorama. So will stars, or better yet, the Milky Way (Figs. 13.16, 13.17, and 13.18).

Fig. 13.16

Object viewed: Lightning. (Image by the author)

Ship: Azamara Journey

Lens used: 35 mm f/1.4

ISO : 400

Exposure: 5 seconds

Comment: The lower ISO helps bring out detail in a bright lightning flash

Fig. 13.17

Object viewed: Southern Cross lightning. (Image by the author)

Ship: Nautica

Lens used: 50 mm f/1.4

ISO: 5000

Exposure: 6 Seconds

Comment: The Southern Cross is centered above the lighting and cloud along with the Milky Way. High ISO was used to bring out star field and Milky Way details

Fig. 13.18

Object viewed: Lightning. (Image by the author)

Ship: Azamara Quest

Lens used: 50 mm f/1.4

ISO : 100

Exposure: 3 seconds

Comment: Full Moon with magic “moonlight blue” color, lightning and the Tasman Sea; note the patterns in the waves

Lightning shots are really easy to take because the lightning is so bright. If you see an area of the sky in the distance and it is active – several lightning flashes over a period of several minutes – and it meets the safety requirements mentioned earlier, consider setting up for a photo shoot. You want an area that is active; active lightning areas bolster your chances of getting several shots to choose from.

Set up on deck at a location that gives you a good view of the lightning area, and minimal deck lighting. Use a tripod with a wide-angle lens, or a medium focal length lens, to take in lots of sea and sky. If you are “fishing” for only a lightning bolt shot, take time exposures of 30 seconds with a wide angle and about 6 seconds with a 50-mm using an ISO of 100 to 400. If you see lightning while your shutter is open you should have captured a lightning shot. Check to see and SAAS.

If you are shooting the full or bright Moon with lightning bolts choose an ISO of 400; a higher ISO will overwhelm the shot. Your exposures will be far shorter, about 3 seconds. You will have to probably shoot a series of shots to get a lightning bolt. If you think you got one check to see and SAAS.

If you are looking to incorporate a star background with an active lightning area, frame the shot and set your ISO 3200 to 5000 for the stars. Your lightning shot will probably be washed out, but you will get the sky. Depending on the lens you use, your exposure can be 30 seconds for a wide angle, to 5 to 6 seconds for a 35-mm or 50-mm lens. If you think you got a lightning shot check to see and SAAS.

Bioluminescence

Bioluminescence is light in the ocean or on beaches caused by marine life.

It is not seen often on a cruise ship, perhaps because the ships are so brightly lit. Even the wake is lit from deck lighting. You might see this ashore if you are walking along a beach.

If you have a calm and dark sea at night, and are topside, just take a look around the wake and the bow for any color in the water. If you see something try a wide-angle lens shot at a high ISO of 3200 to 5000 with an exposure that keeps the ship’s motion to a minimum. You will probably be shooting handheld, so your picture may be a bit blurred in exposures beyond 1/4 second. SAAS.

We have finished Part I of this book and hope we have accomplished what we set out to do – namely, give you some background, appreciation and understanding of astronomy and the things we can see and photograph in the sky. Use the photographing tips and picture settings as references for each object as you start out. As said previously, they are in Part I so you could easily reference them as you start to take your own astrophotographs.

Let’s get to Part II, where we give you some photographic information and philosophy on astrophotography at sea.

Part IIAstrophotography at Sea

© Springer Nature Switzerland AG 2018

Gregory I. RedfernCruise Ship Astronomy and AstrophotographyThe Patrick Moore Practical Astronomy Serieshttps://doi.org/10.1007/978-3-030-00958-8_14

14. Yes, It Can Be Done and How to Do It

Gregory I. Redfern1 

(1)

NASA JPL Solar System Ambassador, Ruckersville, VA, USA

Now that we are through Part I we can explore the “how to” in taking astrophotographs at sea. From the images you have seen in some of the chapters they show that taking pictures from the deck of a ship underway is not only possible but can produce some good results.

In Part II we’ll discuss camera types, “Redfern’s Rules of Astrophotography,” the ins and outs of your ship studio, assessing what the sea and sky will allow for any given astrophoto session, how to process and share your astrophotos and finally, going ashore with your new found pursuit of astrophotography.

Part II is not an in-depth primer on astrophotography and photography, as that would require an entire book and there are plenty of online and printed resources out there already. No, Part II is intended to introduce you to taking astrophotographs at sea – and there are very few if any references about that – with whatever camera equipment you already have or think you might want to buy. A lot of cruise ships have photo shops onboard, so if you are reading this at sea without a camera check to see if there is one onboard.

Once you have read Part II and are familiar with the concepts, properly equipped and ready to start photographing, refer back to Part I for the specific objects you are interested in. Each chapter contains astrophotographs the author has taken at sea (mostly) of the object and the settings used, plus information on photographing the object of the chapter.

The key to any photograph is the camera and lens. With astrophotography this is even truer, as in some instances you are dealing with very faint objects where every bit of light counts. The good news is that if you own any type of camera (digital or film) – smartphone, tablet, pocket camera, video, digital single lens reflex (DSLR), you can take pictures of the sky. The only question becomes how good will they turn out, and there may be some limitations as to what you can shoot with the camera and lenses you have available.

The type of camera you own is what determines how far “out there” in the universe you can go from your ship observatory. There is no way we can cover each and every smartphone, tablet and camera manufactured. But what we can do is provide the basics of each type of camera and what you can do with each from an astrophotography perspective, which is a lot. If you haven’t bought a camera yet, reading this section may help you decide what type of camera you want to take on your cruise.

Yes, there are still film cameras out there, but they are a rarity. There is no real difference in technique between film and digital. The primary difference between the two is the far superior ability of the digital sensor to capture photons of light compared to commercial film. Another substantial difference is in the processing of digital images, which uses powerful software compared to darkroom processes for film.

Used today primarily by photography professionals and purists, film cameras can be used for astrophotography just like any digital camera. Their biggest drawback, especially at sea, is two-fold.

First, you will have no way of developing your pictures while at sea, unless you use one of the instant film cameras that has taken over for the defunct instant cameras of old. But these types of cameras are very limited for shooting the night sky, as they are designed for traditional daytime and flash photography. With film cameras you will also have no way to determine the quality of your astrophotos when you take them, in order to make needed adjustments. Another big disadvantage is that you cannot carry enough film to equal the number of shots you can take digitally – in the thousands, depending on picture size and type.

Second, you need all the help you can get in pulling in light from faint and dim objects in the night sky, and you want to shoot as fast as you can to mitigate ship motion. This is where the digital camera’s sensor runs circles around film – there is no comparison. The digital camera sensor will capture far more light from dim sources than film. Period.

If you haven’t bought a camera yet, when you decide to do so, go digital. You will never regret doing so. Our discussion in Part II will center on digital capability.

Smartphones and tablets are amazing pieces of technology, as they combine telephone, computer and camera (including video) all in one. Nearly everyone on a cruise has a smartphone, with tablets being a very distant second. These can be used to plug into the ship’s Internet. However, this may be a costly item for you, plus there are probably going to be times when the ship’s network will be down for a variety of reasons. Ships usually allow for you to have one-device-at-a-time use on their network.

Your smartphone or tablet can also have an astronomy application loaded onto it that will help you in observing the sky (see Chaps. 1, 3 and 4). This is very useful, and pretty much essential to getting the most out of your sky viewing and astrophotography sessions. Your astronomical software will help you plan your observing and astrophotography sessions as well as serving as an astronomical reference.

You should also consider a tripod for your smartphone or tablet. If you are going to take time exposures of any length it is tough, but not impossible, to hold your device steady. You may want to get one of the small flexible tripod stands for your smartphone that can be morphed to fit around just about anything. They would be good for affixing to a deck railing for your shots. These types of stands do not work with tablets, which are too large for them.

If you even think you will want to get more into astrophotography or regular photography a good carbon fiber folding tripod – sturdy with low weight – with a 3-way locking ball head is something to consider. Carbon fiber tripods are good because of their strength and light weight, plus they can be packed easily in your luggage. A 3-way locking ball head is a must, because you will be shooting at all kinds of angles, and you want to make sure you minimize camera movement when photographing at horizontal and high angles. Having two locks for altitude adjustment is better than one. For azimuth adjustment one lock is sufficient.

If you use a typical 3-way locking ball head it will probably have a camera body adaptor plate that screws into the universal tripod socket at the bottom of your camera body. This vice-like adaptor has ridges that fit into the top of the ball head. You tighten the vice with a knob for a nice, secure fit.

In the dark it is very easy to turn the wrong knob. If you loosen the camera adaptor plate knob by mistake instead of the other 3 locking knobs your camera has a very good chance of falling to the deck. Usually this knob is smaller than the other three, but why take a chance? Use your red headlamp to confirm visually what knob you are loosening.

If you think you will want to use heavy telephoto lenses when you are ashore another option to consider is using a geared tripod head instead of the 3-way locking ball head. Even the best 3-way locking ball head is going to have some play in locking down the axes and perhaps even some slippage with a heavier lens-camera combination.

The geared tripod head is much more precise in positioning the camera, as it uses gears on all axes to position the camera. This setup also requires a more substantial tripod, so you will be carrying around some extra weight, but it would work at sea and on land. The overall advantage is precise positioning and using just one tripod-head system. The disadvantages are the extra weight and greater cost.

If you go this route make sure you check the weight limit specification of the geared tripod head and tripod to hold the whole setup. Better to go to higher weight limit models than push too close to another model’s maximum that might not be sufficient.

You can get a smartphone or tablet adapter that will work with this full-fledged tripod that will give you far more options than trying to hold your smartphone or tablet steady. A big plus for going this route is that you can “grow in capability” if you upgrade to another type of camera. A good tripod and accompanying heads will likely be part of your camera equipment bag someday.

Another recommended accessory and relatively inexpensive for your smartphone or tablet (Android and Apple) are add-on lenses that attach to your device. There are different types of lenses out there – fisheye, wide angle, telephoto, and 3-in-1 combining lens types. They are inexpensive and add capability to your device for photographing the sky. This true optical lens capability is far superior to trying just digital methods to zoom or stretch your photographs. When ordering you will have to make sure it is compatible with your device, especially the size of the camera lens.

As to photographing the sky with a smartphone we have to limit comments to using the iPhone 5s and the 6s. The 6s is ancient smartphone technology, especially when it comes to camera capability, but it does work. The current generation of smartphones have amazing capabilities, especially the latest iPhone with its TWO camera set up with optical and digital zoom, 12 megapixels and optical stabilization – wow.

This author has had no astrophotography experience with the iPad, Android smartphones and tablets. What turned up from researching the subject was a reliable source that provided two suitable applications for upgrading your Android smartphone or tablet capabilities for night sky photography – Camera FV-5 and Open Camera. These applications seem to have good features useful for taking night sky photographs. See the “Suggested Reading and Internet Sites” section for this chapter.

For iPhone and iPad users the NightCap Camera application really transforms your device into a far more capable camera for shooting the night sky. I do not have any affiliation with the company other than as a user, so this is not a commercial endorsement. I have used its predecessor NightCap Pro – the latest upgrade changed the application to NightCap Camera – and I have taken pictures of planets, stars and constellations with it. See the “Suggested Reading and Internet Sites” section for this chapter.

This application truly changes your iPhone and iPad into an astrophotography capable camera. You can change the ISO, use different modes such as stars, star trails, ISS and meteor, and take time exposures, including unlimited exposure time. Plus the application uses AI to help you. If you want to try your hand at astrophotography with minimal investment, this is the way to go. You will have to read the tutorials online to get familiar with the application, but it is pretty user friendly.

If you pair up this application with a state of the art iPhone you may have some pretty amazing capabilities. You might even try taking Milky Way shots on a tripod with the enhanced ISO and unlimited time exposure capabilities.

With a smartphone or tablet you can try to take astrophotographs (and even video) of anything in the night sky and see how the results turn out – “Nothing ventured, nothing gained.” The Moon, the brighter planets like Venus and Jupiter, the brightest stars are worthwhile efforts to photograph. And depending on what type of smartphone and tablet you have, you may have even greater capabilities with software and accessories described previously.

Modern pocket, “point and shoot” or compact cameras are extremely capable, easy to use and pack. They have still found popularity and usefulness in the day of smartphones and tablets, as they are full-fledged cameras that carry quite a photographic punch in a small package, even for astrophotography at sea.

Looking at the dazzling array of compact cameras that are available for purchase was amazing – there were so many. Most major camera brands have several models, and price ranges weren’t too bad. There are several things you need your compact camera to have or be able do for astrophotography:

Have a manual mode (as opposed to being fully automatic only) that allows for taking different exposure times to include taking time exposures for at least 30 seconds. This will allow you take time exposures of stars, planets and perhaps even the Milky Way.

Have a quality optical zoom lens (as opposed to having just digital zoom) that brings objects in closer, especially the Moon and eclipses.

Be adjustable for ISO so that you can change ISO from low, 100 or 200, to high, 3200 or better. This will give you the range necessary to cover bright and dim astronomical objects.

Be able to mount your compact camera on a tripod; just make sure it has the universal screw socket.

Another camera option to consider is the mirrorless CSCs, or compact system cameras. These cameras do not use a mirror to direct light to the viewfinder and are becoming more and more popular. The lack of the complex mirror system makes these cameras smaller and simpler but still offer lens interchangeability, unlike pocket cameras. As of this writing Nikon is preparing to unveil its own mirrorless full frame CSC camera with a new lens mount that is 11 mm wider than its storied “F mount.” This brings up the intriguing possibility of faster lenses that can take advantage of the extra mount space for more “glass” in the lenses.

OK, now we get to the currently most capable of the camera types for astrophotography, the modern digital single lens reflex camera, or DSLR. Having a DSLR that uses interchangeable lenses is the way to go, as you will need and want different lenses as you get farther along in astrophotography and photography overall. A fixed-lens DSLR will work, but it will limit you somewhat as to what you can achieve compared to a lens interchangeable DSLR.

As most photographers do, when you buy glass (lenses) for a certain camera brand you stick with them as you upgrade the camera body. Why? Simple – cost. Camera makers use their own type of lens mounting system, and although it is possible to get mount adapters it is not “pure” and adds one more level of complexity. Even though you may be able to mount a certain camera lens brand to a different brand camera body this does not necessarily mean full capability of the lens – auto focus, different program modes, etc. If you mix and match you have to read the fine print to make sure of full compatibility between the two.

Lenses are where the rubber meets the road, or more properly, photons from the universe meet your camera. These photons of light come from a wide variety of astronomical objects, large and small, dim and bright, point source to extended, and your lenses collect light from them all.

Never skimp on lens quality, as this, more than just about anything else, will impact your resulting image quality. You pay for that quality, but with proper care a quality lens should last for life. Many lenses that are fifty years old work just as well when they were new. But treat them well!

Whenever you get a new lens, buy a clear filter, also known as a UV or NC filter (Nikon) for it at the same time. When you receive the lens inspect it for any glass surface defect or optical coating issues. If there are none put the clear filter on the front lens and never take it off. Doing this protects your lens and keeps it clean. It is a lot easier to clean salt and sea spray off a filter than it is a $2,000 lens!

A 14 mm f2.8 prime lens has to have a 150-mm square lens glass filter and separate filter support system due to the very large curvature of the lens. The filter support system protects the front lens but also acts as a light block that cuts out stray side light far better than the original petal lens hood. Without this you could see bothersome lens flares in your pictures. Sure, you could try to eliminate them post processing, but why not get rid of them in the first place?

The whole filter setup was $350 but is worth it for being able to get the most out of this expensive and highly capable lens while protecting it. The filter is a light pollution clear glass filter that reduces yellow light, usually the most common form of light pollution. Even at sea light pollution from shore can sometimes creep into your pictures, so this does help to reduce it.

Here are some recommendations based on the author’s use of Nikon lenses that work well for at-sea astrophotography:

Nikon 14 mm f/2.8 Wide Angle

This lens captures a large segment of the sky, making it perfect for photographing the Milky Way and night sky scenes. It can collect a lot of light, allow for 30- to 35-second exposures in a steady sea and provide decent detail. See the next chapter for more on using this type of lens.

Nikon 35 mm f/1.4

This is a gem of a lens, as with its large light-collecting capability and longer focal length it can add true depth and breadth to a section of the Milky Way, a constellation, the various sky glows and planetary line-ups.

Nikon 50 mm f/1.4

With its extra focal length this lens does everything the 35 mm does but just brings it in a little closer. This is a good lens for shooting the star and dust clouds of the Milky Way and sky glows that will fit in the frame.

Nikon 28–300 mm f/3.5-f/5.6 Zoom

This is an all in one lens for shore excursions. At sea it can be used for shooting planetary lineups with the Moon, as you can get in very close. Shooting the Moon with a 300 mm and then cropping the image can produce a very nice lunar portrait.

If you could have only one lens to start with it should be the 28–300 mm, as you would get the best of having a decent wide angle and zoom to telephoto capability. Other camera brands offer the same capability in lenses so it is your choice as to what brand you purchase.

Just about any quality DSLR will serve all of your photographic needs, including astronomical ones. The Nikon D810a DSLR is as of this writing (2018) the world’s only stock full frame (FX) DSLR dedicated to astrophotography. Its sensor is sensitive to hydrogen alpha light, which is seen in emission nebulae (clouds of ionized hydrogen). Nikon does not recommend the D810a for non-astronomical photography, but you can use it for other photography. Only the brightest daytime images may show a little preference to a reddish tint, but this is negligible. The D810a does it all, including mounting to a telescope, which we will discuss in Chap. 19.

An early DSLR was a fixed lens Nikon model followed by a D5000 and D5200. The fixed lens model was when DSLRs were just coming out and was more affordable than a “professional grade” DSLR, which was about the only other choice. Canon came out with an astronomical DSLR camera body, the D20a, but it wasn’t around long. There are aftermarket vendors that will remove stock DSLR sensors and replace them with sensors that are astronomically useful in that they are tuned to hydrogen alpha light (see the Suggested Reading section for this chapter), but that is not really necessary for taking astropics at sea. To do that all you need is a good quality DSLR.

If you are shopping for an all-in-one DSLR camera here are the essentials that you want to get for use in astrophotography:

Interchangeable lenses capability.

Full control (manual mode) over exposure time, ISO, f/stop and other settings such as flash, picture size and type (RAW, JPG, TIFF).

Bulb or unlimited time exposure capability, at least 30 seconds for time exposures.

An ISO range from 100 to 200 up to at least 3200 or higher.

Manual focus capability, as many objects will be too dim for autofocus.

Shutter release capability and/or shutter release delay. A shutter release physically connects to your camera through an interface that allows you to push a button to take the exposure. This negates movement of the camera, which would show up on your picture. Some shutter releases will lock in place for an extended time exposure until you release the lock. Some cameras may have a shutter release delay so that when you push the shutter button the camera waits for the specified time before the exposure begins, in order to minimize camera movement. This capability becomes vital when you are doing astrophotography with the camera and a telescope, as you shall see in Chap. 19.

LCD viewing screen (with tilt out capability if available, as it makes for far easier focusing and viewing).

Some nice to have features:

LIVE VIEW with zoom. This allows you to see what the camera sees, if it is bright enough to show up on your viewing screen. You can use this feature to focus your camera and zoom in for greater precision in focusing.

Video. Many DSLRs are able to take HD and 4 K video, which can be useful during eclipses and, as you shall see in Chap. 19, at the telescope.

A “mirror up” capability. When you look through the viewfinder of a DSLR there is a mirror that reflects the image formed by the lens up to a prism that brings the view to your eye. This mirror is moved up when the shutter release button or cable is activated, which can result in “mirror slap” – the vibration of the camera due to this movement. This is not a significant issue for taking pictures at sea – manually pushing the exposure button causes far more movement – but this capability becomes vital when you are doing astrophotography with the camera and a telescope, as you shall see in Chap. 19.

Camera retailers usually have very decent DSLR “kits” that will include a camera bag, some cleaning accessories and two lenses, such as 18–55 mm and 55–200 mm or similar specification. This makes for a very capable and compact astrophotography-photography setup. The camera bag is something that all astrophotographers need – something that organizes your camera gear and allows you to carry it around securely.

Also have some camera and lens cleaning gear as recommended by your lens and camera User Manual. These items can get dirty in an at-sea environment. Sea spray and rain get on camera body and lens. A cleaning kit containing a camel hair brush, microfiber cloths, Q-tips, blower bulb/brush, quality lens tissues and lens cleaner are a must.

You will also need to buy the appropriate memory card for your digital camera. There is a whole universe out there of memory cards with different storage sizes, throughput speeds and other considerations. You have to make sure that you buy the right memory card for your camera. You don’t want to go to sea and find out that you have the wrong kind of memory card!

Take test exposures with the memory card inserted and then view the results to insure complete compatibility with your camera. Have a spare with you in case something goes wrong with your memory card or if by chance you end up exceeding its capacity – which is hard to do with high capacity memory cards. Your ship’s photo shop may have memory cards on board for sale as well, but the safe bet is to obtain and test them before you go to sea.

The bottom line for this chapter is that any camera can take astrophotographs at sea, but there are limitations that have to be taken into consideration for smartphones, tablets, film cameras and compact-pocket-point and shoot cameras. For DSLRs the limitations are far fewer, and it really becomes an upgrade in capability as you acquire lenses and other accessories – perhaps even for use at a telescope.

Get that tripod and 3-lock ball head! You will never regret having them available to use. The same goes for a cable release. Oh, and did you acquire that camera backpack we discussed in Chap. 1? You are going to find out in the next chapter how vital having it really is.

If you have one type of camera already use it to start and learn with. Or, if you prefer, go ahead and upgrade to the DSLR if you already don’t have one. If you are interested in taking your photography to the top level you will end up doing this anyway, and your astrophotography efforts will benefit as well.

Get to know the sea and sky through your camera lens by taking astrophotographs. The next few chapters will help you do so aboard your ship observatory.

© Springer Nature Switzerland AG 2018

Gregory I. RedfernCruise Ship Astronomy and AstrophotographyThe Patrick Moore Practical Astronomy Serieshttps://doi.org/10.1007/978-3-030-00958-8_15

15. Redfern’s Rules of Astrophotography at Sea

Gregory I. Redfern1 

(1)

NASA JPL Solar System Ambassador, Ruckersville, VA, USA

These seagoing astrophotography rules are based on hard knocks, mistakes and frustration all experienced while at sea aboard 28 (and counting) cruises totaling over a year at sea. I’ll share my growing pains with you as they are instructive and may help you to avoid them. Adhering to them will go a long way in getting astrophotographs that you will be proud of and even amazed by.

Here are Redfern’s Rules of Astrophotography at Sea:

Rule #1: Read the Camera Manual

Rule #2: Do Rule 1 – Know Your Camera

Rule #3 : Keep a Hand on Your Camera and Gear at All Times

Rule #4 : More Is Better – Shoot, Shoot, Shoot Pictures

Rule #5 : Use the Highest ISO Feasible

Rule #6 : Speed Wins – Use the Fastest Shutter Speed

Rule #7 : Use the Widest Angle Lens You Have

Rule #8 : Have a Red Headlamp for at Night

Rule #9 : Keep the Color Real

Rule #10 : Take What the Ship, Sea & Sky Give You

Now that you have read them in their entirety, let’s examine each one to see how they came about and why you need to follow it.

Rule #1: Read the Camera Manual

First, do not use your camera until you have read the manual.

As first glance this seems like a no brainer , but in talking to countless passengers (and people who attend my land based astrophotography lectures), it appears this is not the case. People give many reasons for why they haven’t read their camera’s manual – “I lost it,” “I don’t remember what it says”, “I didn’t understand it,” or most often, “No, I haven’t read it”.

Regardless of your camera type, you have to read the manual about your camera before you use it. Whether it is online (all cameras should have their operating manuals online via their manufacturer’s website and available for downloading) or in printed format, you need to take the time to read it, absorb it and apply it.

By the way, Rule 1 and Rule 2 apply for any lenses or accessories, like a tripod, that you buy for your camera. Read their manuals, too, for they will become part of your camera and affect your overall astrophotography efforts. Keep them with your camera’s manual.

It is not easy to sit down and go through a lot of pages about your camera. The manual for the Nikon D810a is 407 pages, not including the insert for the astronomical features. And, oh by the way, it goes with the camera aboard ship or wherever the camera goes! The more capable your camera is, the more complex it will be and the longer the manual, which equates to needing more time to read it and become familiar with your camera.

The first part of your camera manual will be a variety of safety warnings, the first of which is, by the way, about solar safety. The Nikon D810a manual has two warnings pertaining to solar safety that tell you to keep the Sun well out of the frame when shooting backlit subjects. “Sunlight focused into the camera when the Sun is in or close to the frame could cause a fire.”

There is also a warning to not look at the Sun through the viewfinder: “Viewing the Sun or other strong light source through the viewfinder could cause permanent visual impairment.”

Finally, there is this warning: “Never point your camera at the Sun unless a safe and approved solar filter is on the front lens” This one should be well known to you by now.

See Chaps. 5, 10 and 13 for more solar safety notes.

The remaining safety notes in the manual (and these are pretty universal) are ones that we all are well advised to follow, as they pertain to the safety of others, including infants, and the safety of the camera itself. These need to be committed to memory and followed to the letter by you.

Your manual will probably have a “Getting to Know the Camera” section that will consist of a detailed drawing of your camera – probably just the camera body – showing the location of all of the buttons, interfaces and dials. Your camera body drawing should have a number assigned to each feature that corresponds to a sequentially numbered list that gives the name of the numbered item and the page numbers in the manual that describe its function in detail.

There also should be a similar drawing for your camera’s control panel (if it has one, and you really shouldn’t buy a camera without one) and the viewfinder. These tell you what the camera’s settings are and a ton of other information at a knowing glance.

After the safety notices, this is the most important section of the entire camera manual – “the Rosetta Stone” – that will help you decipher how to operate your camera. You will want to first read this section, probably several times, to get familiar with it. And have your camera in your hands (with the neck strap around your neck to prevent you from dropping the camera) to physically touch each feature listed for the camera body while you say aloud the name of the feature. This method really helps to train your brain.

Once you have it down in daylight, repeat the procedure in the dark, using Rule #8 until you feel comfortable operating in the environment you will be in for the majority of your astrophotography sessions. You should know the main features of your camera, such as the shutter release (and where to interface your cable release if you have one); how to mount your camera to your tripod (again if you have one); how to change lenses (if you have this capability); setting ISO, f-stop, exposure time, flash off and other necessary adjustments.

Now there is one more step you need to take. You need to do a dry run on land, just like you will at sea. The only real difference will be that there will be “no motion in the ocean” for you to contend with – and that is a good thing as you are learning the ropes of astrophotography with your camera. We will go through the rest of my Rules and explain them so you can apply them in this final step before you go to sea.

Rule #2: Read the Camera Manual

Rule #1 is so important that we made Rule #2 to remind you. You really need to know the layout of your camera in order to be safe and take astrophotographs. Skipping these two rules is unsafe and will hold you back from becoming the astrophotographer you can be. So, please, take the time to start out safe and smart.

Rule #3: Keep a Hand on Your Camera and Gear at All Times

This rule partially comes from hard experience ironically learned on land, where if you let your guard down and allow fatigue to set in, you can ruin a $4000 camera. I was on a great road trip to Yellowstone National Park among other stops following a cruise. I had a car rental waiting for me at Seattle-Tacoma airport coming off of Oosterdam .

Several days of driving some long distances and staying in motels had left me a bit fatigued plus I was putting in some serious foot mileage at all of these wonderful places. So I was feeling a bit tired and not enough coffee as I went to answer Mother Nature’s call early in the morning before going to see Old Faithful.

Well, let’s put it this way. I didn’t think the hook on the toilet door would hold my heavy Nikon with lens; the floor didn’t look like a good proposition either, due to recent guest visits. The toilet itself didn’t have much of a structure to it where you could put a camera on the top lid of the reservoir. My choice? Put the camera on the steel structure surrounding the toilet paper rolls. Bad choice.

I did not notice that there was a slight downward angle to the structure. So, at a moment when no hands were free, gravity and the slight angle combined to overcome the friction between the camera and the steel. The camera didn’t fall all that far, a couple of feet, before impact with the concrete floor. Everything looked OK – lens, camera body. But where the camera lens attaches to the camera body – a solid metal ring that keeps the lens parallel to the camera – was bent – and non-repairable. That is why you have insurance on a high ticket item like your camera body. What I should have done is put the camera strap around my neck. Lesson learned and new camera ordered and received.

As described in Chap. 1 you should have a high-quality camera backpack for your camera and lenses, computer and incidentals, and “gotta haves” such as medications, extra glasses, etc., when you go on a cruise. The camera backpack goes on board the plane and the ship. You will have good protection for your gear and the tripod in a side pocket/set of straps to secure it. You can carry it like a briefcase for brief distances like going through the airport and in the aisle of the plane making it to your seat. For a longer haul it goes on your back and has hip and chest straps, a rain cover and good shoulder strap padding – in other words good ergonomics. It can go a long way on your back getting aboard ship via elevators, gangways and into your stateroom.

It also is the safest and most convenient way to get your camera gear topside on board ship, especially at night. You can put your camera on the tripod in your stateroom with the camera neck strap wrapped around your hand that holds the tripod and camera. That way if the camera comes off the tripod you still have positive control of the camera. The backpack is on your back and your other hand is free to use the elevator, open doors and grab hold of something in case of motion in the ocean.

When you get to where you are going you already have your red headlamp – Rule #8 – on your forehead. In fact you can put it on in your stateroom so you can switch to red light and start working on getting your night vision in place although the stateroom passageway and ship interior will probably be well lit as you make your way topside. Usually it takes about 20 minutes or so for your pupil to get to its maximum size – if and when you get to a dark spot on the ship. Even if you are in a location that has partial illumination it usually is not enough to see what you are doing with the camera. Remember, you are trying to get to the darkest location possible for your astrophotographs, so if you are successful in doing so you will need red light to see what you are doing.

At your spot on the ship where you intend to set up your tripod (or use the ship’s structure for bracing) see if there are any deck lounge chairs available. You can set your camera/tripod down on it while you take your backpack off. If one isn’t available carefully set your camera/tripod down on the deck right next to you. If a deck lounge chair is available set your backpack on it with the side that you access your gear from facing up. If one isn’t, put it down on the deck carefully right next to you.

Ship Tip

Do not leave your gear unattended on deck. Other guests, ship crew members and ship security personnel will be topside at all hours. At night and in dark areas of the ship – where you may be – these people may be out for a stroll or making their rounds. In a dark spot on ship they may not see your gear if you leave it unattended and could trip over it or knock it over – not a good thing either way. If you are right next to your gear with your red headlamp on you will get curious looks and maybe even inquiries, but all will be well with you, them and your gear.

Always zip up your camera backpack after you access it so that if it tips over, you trip on it or it somehow falls the contents will stay put. When you set up your camera/tripod you will still have that neck strap wrapped around your hand so that if the camera/tripod goes you are still in positive control of the camera. When you use ship bracing, have the neck strap wrapped around your hand pretty tightly.

When changing lenses on a camera mounted on a tripod use the following procedure.

1.

Put on the front protective cap for the lens.

2.

Remove and store the lens hood on the camera lens.

3.

Take the camera off of the tripod and put the neck strap around your neck.

4.

Have the camera body protective cap and the rear protective cap for the lens you are changing out available to put in place when you change the lens. 

5.

Closely hold the camera over the camera backpack or better yet, over the camera backpack sitting on the nice wide deck lounge chair. This helps protect against dropped lenses. If they fall they have a nice soft spot to land.

6.

Remove the lens, put the camera body and rear lens protective caps in place.

7.

Stow the lens in its place in the backpack.

8.

Retrieve the new lens and remove its rear protective cap.

9.

Remove the camera body protective cap.

10.

Put the new lens on and make sure you have a correct fit.

11.

For Nikon the camera body and rear lens protective caps screw into one another. Do this and place them in the camera backpack in the section that holds the camera body. This way you know where they are and they are easily accessible. I put them in a plastic sandwich bag to protect them and make them easier to find.

12.

Put the camera on the tripod and test for a secure fit by wiggling the camera. There should be no wiggle.

13.

Put the lens hood in place.

14.

Transfer the neck strap to your hand.

Do this procedure each time, and your lenses lives will be good.

Astrophoto Tip

Carry extra ziplock sandwich bags in your camera backpack to hold things like camera and lens protective caps, cable release, memory cards, etc. They protect the contents from rain and sea spray and just as importantly are easy to see at night. Put any loose items such as the tripod mounting plate(s) in them.

If for some reason you have to detach your hold from your camera do not be more than a step away, in case the ship rolls or someone approaches so you can be there to save and stave off unfortunate circumstances for you and your camera. More than a step and you are playing Russian roulette with your camera that may catch up to you at some point in time.

When you finish your session make sure your camera backpack is zipped up before you return to your stateroom. Nothing like an unsecured bag dumping out its contents onto the deck in the dark!

Rule #4: More Is Better – Shoot, Shoot, Shoot Pictures

We are so fortunate to live in an age where technology enables us to shoot literally thousands of pictures using a small memory card in our camera. It so much easier than the days of ‘wet film,’ where we had a maximum of 36 exposures to work with at a time and had to develop the film before we knew how well we did in capturing our elusive photons from the universe. Unless you go with a film camera it really is a new age of astrophotography, one that you should wholly endorse and use to great advantage.

With the digital age of cameras we can shoot a picture, analyze it at the camera itself – if you have an LCD panel that is part of your camera set up – make settings adjustments and shoot again. Shoot, analyze, adjust, shoot – now you really know where SAAS comes from and what it means.

It may take more than 20 tries to get “the shot” that you were hoping for. It is very, very rare to take just one astrophotograph. Sometimes it turns out that the first shot is the best one after reviewing the others. But with each additional astrophotograph you are trying to improve the shot.

You can do this by changing the composition of the astrophotograph, that is, moving the camera to take in the shot from a different perspective even though the picture itself is “good.” Sometimes the camera captures what the eye can’t see, and with such an easy ability to shoot as many as you can, why not?

This really comes into play when you are shooting the Moon, planets, clouds and waves because each of these presents possibilities with the way they look and interact. Moonlight on the waves is never ending; moonlight playing with the clouds changes every second; and if you are framing moonlight, clouds and waves all in one shot, this applies as well. Use your prime lenses for these types of shots.

If there is a planet you are photographing among the stars, or multiple planets or the Moon and planets; this is when you will want to take multiple shots to get “the right one.” If you are shooting a planet against the stars you should use a prime lens to get the shot with the widest coverage and light-gathering capability. If it is the Moon and planets or two planets near one another you might want to go with a zoom lens so you can get them closer together with some detail. Once again having lens interchangeability on your camera is a big plus, as is shooting more pictures.

Rule #5: Use the Highest ISO Feasible

In the days of film the acronym ASA (American Standards Association) placed next to a number, ASA 400 for example, was used to determine the film speed you were buying. The higher the number the greater the film’s sensitivity to light, which meant that it was possible to take faster exposures than films with lower ASA numbers and hence slower film speed. There were films with ASA 25 all the way up (eventually) to ASA 1000 or more. The general rule was that with the higher ASA films, especially the 1000+ films, grain size of the emulsion used to record the light would begin to be an issue.

We now have the acronym ISO (International Organization of Standardization) that denotes film speed. It will be used with a number, ISO 100 for example, to show the film and/or digital speed you are using. Once again the higher the number the faster the film speed and greater sensitivity to light. The problem of high film speed and grain still applies at the higher film/digital speeds. For the digital world ISO can reach 12,800 or higher, way higher, but once again at a cost of “grainy” pictures. High ISO effects can be reduced somewhat by post-processing; we will talk about that in Chap. 18.

There are some Internet sites in the Suggested Reading section for this chapter about ISO and DSLRs, so you can read how this works. A higher ISO does some tricks to improve taking pictures in dimmer conditions. This is important in astrophotography at sea, as you are trying to overcome two problems – usually dim photographic subjects and the motion of your ship in the water. Being able to shoot in dimmer conditions allows you to use a faster shutter speed (Rule #5), which can, in many cases, minimize the ship’s motion in the ocean.

What initial ISO to use depends on what you are photographing and how the sea state is – calm, choppy, an arcade ride. By going back to the chapter that deals with the type of object you want to photograph you can see what ISO setting was used and use it as a starting point. Then Rule #4 takes over.

Rule #6: Speed Wins – Use the Fastest Shutter Speed

This rule is next because, next to ISO, shutter speed is the biggest factor in your nighttime astropics. I say nighttime because if you are shooting during the day you will probably be able to overcome motion in the ocean to make a good shot with “Auto” mode, where the camera does the thinking for you as to your settings of ISO, shutter speed and f/stop (aperture). It is at night or in dim light with the ocean in motion that you have to find the “sweet spot” that brings it all together – ISO and shutter speed – for a good picture. At night or in dim light you will have your camera lens wide open to its lowest f/stop to get all the light you can. Once again Rule #4 becomes your ally.

Looking at the appropriate settings for the object you wish to photograph will give you your initial start, and you can take it from there. Ship’s motion is your primary consideration, as you want to make your picture as steady and free of ‘EKG’ artifacts, i.e., wiggles in the picture, as you can. Frankly, as you will see in Rule #10 and the chapter that follows there will be times when you have to call it a night.

You can use Rule #5’s higher ISO to try and bring Rule #6’s faster shutter speed into play. This usually applies to objects that are somewhat bright, like the Moon, brighter stars and planets. You are trying to photograph them as cleanly as you can and applying Rule #5 and #6 in addition to Rule #4 so you can get that shot you are looking for. If you are taking long exposures of 10, 20, 30 seconds Rule #4 really won’t apply, because if the ship has motion it will usually show up in an exposure of as little as 1 second. A little jiggle in the star images, is probably OK, especially if you are shooting an extended background object like the zodiacal light, an aurora or the Milky Way. If the motion isn’t too bad you can still capture these objects with fairly decent detail. Don’t lose a great astrophotography opportunity just because your ship observatory is moving. You will just have to SAAS to see.

Rule #7: Use the Widest Angle Lens You Have

We have included a Nikon Primer on lenses in the Suggested Reading section, so you can have a trusted source to learn what is best from an astrophotography perspective. They are the only major camera brand with an astrophotography-dedicated DSLR, the D810a. Accordingly, they have good information on their Nikon website about astrophotography.

Any lens used in a full frame camera that is smaller than 35 mm in focal length is considered a wide-angle lens. They are superb for use at sea because they cover a lot of area and in calm or mild motion seas that can allow for exposures up to 30 to 35 seconds with a 14 mm or about 5 to 6 seconds with a 35 mm before any noticeable star trailing occurs in the astrophotograph. Combine that with a fast focal ratio of f/2.8 to f/1.4 and you can pull in a lot of sky, such as the Milky Way, the aurora and other wide-area astronomical objects.

The brand name lenses are expensive but remember what I said in the last chapter about buying glass – buy the best you can afford because they are what makes your picture and they last a lifetime with care.

Included among the at-sea photographs, usually of the Milky Way, are those taken with a 14 mm f/2.8 wide-angle lens. They show the power of the wide-angle lens to get good Milky Way shots. Having a camera lens like this in your camera bag really opens up your astrophotography options and here’s why.

A wide-angle lens provides superior light-gathering capability with a fast focal ratio, area coverage and excellent exposure time. All of this combines to help you get great astrophotographs and minimize motion in the ocean from the ship. Unless the ship is an arcade ride, use of a wide-angle lens, especially when combined with Rules 4, 5, and 6 , will allow you to shoot faster to minimize ship motion and pull in a good shot.

It is highly recommended that you make a wide-angle lens part of your camera bag. If push came to shove as to selection with money as a prime consideration and no chance of buying several lenses in the future, you should make a wide-angle lens a top purchasing priority for all of the reasons we have mentioned. You may want to consider a wide-angle/telephoto zoom lens instead of a prime lens to get more bang for your camera lens buck. Just make sure you buy quality glass.

Rule #8: Have a Red Headlamp for at Night

Even though this rule is far down on the list it is an essential one for you to operate safely and efficiently at night doing astrophotography as described in Rule #3. My headlamp also has white light capability and even flashes S-O-S for emergencies, which make it part of my land lubber equipment as well. Speaking of land lubber, when you get to Chap. 19 you will once again see how vital this accessory is to your astronomy/astrophotography efforts.

Be sure to carry spare batteries for your headlamp, which can go into the camera backpack. While we are at it, let’s just go over what accessories you really need to bring with you other than manuals, tripod and locking head, shutter release, and protective lens filters we already discussed for use at sea and perhaps someday, ashore, for your astrophotography. We discussed some of the other items you need in Chap. 1, but let’s zero in on what goes in the camera bag.

Spare Batteries for Your Camera

Every digital camera is powered by a battery of some sort. Make sure you have a charger and an actual spare battery for your camera. In fact, have two fully charged batteries when you start a session so you can change out and keep going when one gets low.

Lens Cleaning Kit

Follow the cleaning recommendations of your camera body and lens manuals – Rule #1 and #2 apply here. When you get sea spray on your lens filter and camera body – and you will – you will be glad you have a cleaning kit. You will also thank that protective glass filter layer between your expensive lens and the elements. Your kit should have at minimum Q-tips, a blower bulb to blow dust and particles off of the lens filter, a camel hair brush to assist in particle removal, lens cleaning fluid and lens cleaning tissues, and microfiber cloth. Make sure the lens cleaning fluid is in a leak-proof container, as you do not want this leaking out into your camera bag. You can keep it in a ziplock bag as extra protection. Check out the Internet site containing a video on lens cleaning in the Suggested Reading section for this chapter.

Extra Lens and Camera Body Protection Caps

These are easy to lose. It is good to have extras on hand when yours go to Davy Jones’ Locker.

Extra Camera Body LCD Panel Protectors

It is a good idea to have a glass protector on your LCD panel on the back of your camera body. This is in addition to the hard plastic protector provided by Nikon and possibly other camera brands. The double protection is necessary to avoid scratches. For really fine focusing you can take the hard plastic cover off and get a perfect rendition of the image through the glass protector.

Extra Tripod Plate Adapter for Your Camera Body

Many tripod ball heads use a system where a small adapter plate screws into the universal tripod socket at the bottom of your camera body. If you lose this adapter plate and don’t have a spare you might lose use of your tripod for the duration of the cruise, unless your ship’s photo shop or one on shore has them for sale.

Rule #9: Keep the Color Real

Many astrophotographs have been processed to the point where they are not a valid representation of the astronomical object they show. There are also many photographs that have been processed with additional and separate photographs that portray the astronomical object and/or scene in such a way that could never happen naturally.

This is acceptable if it is explained upfront as an astronomical image that has undergone extensive processing and/or multi-shot composition. But alas, this admission is not seen very often. It is not recommended that you add color to your astronomical photographs. As you shall see in further detail in Chap. 18 you should use very simple photographic processing software and take full advantage of it except for the addition of color. Your colors are as real as nature itself.

You should adhere to the same level of honesty and professionalism in astrophotography as described here.

Rule #10: Take What the Ship, Sea & Sky Give You

This rule is so important that we have devoted a whole chapter to it. Chap. 17 is essentially the non-technical and philosophical culmination of the author’s astrophotography experience at sea. So keep on reading, and we will revisit this rule in Chap. 17.

© Springer Nature Switzerland AG 2018

Gregory I. RedfernCruise Ship Astronomy and AstrophotographyThe Patrick Moore Practical Astronomy Serieshttps://doi.org/10.1007/978-3-030-00958-8_16

16. Preparing for Your At-Sea Astrophotography Session

Gregory I. Redfern1 

(1)

NASA JPL Solar System Ambassador, Ruckersville, VA, USA

Now that you know Redfern’s Rules we’re going to take you through a step by step process that you can use each time you conduct an astrophotography session. As you go through the steps it will become clear why each step is done and why Redfern’s Rules apply. We’ll provide appropriate tips as we go along that are very useful and are based on the author’s sea experience. You may want to use this as a checklist for your sessions at least in the beginning. Never hurts to have a proven process checklist.

Astro Tip

Before you go to sea and using the cruise itinerary, make up a “My Cruise List of Astronomical Objects of Interest” that are going to be present during your cruise by consulting your astronomical references, software, planisphere and/or star charts.

The dates, ship’s predicted location and resulting local time can be used to determine if your object(s) of interest will be visible and at what time and location in the sky. Be they planets, the Moon, Sun, aurorae, constellations, eclipses, the zodiacal light, etc., this is essential to proper planning.

Continuing from previous chapters that recommended practicing techniques or processes ashore before going to sea, you want to do some of these practice sessions during the day and then at night over the course of several weeks before you plan to use your camera on a cruise. If you do not have the luxury of weeks to prepare and train you still have to read the camera manual before you use your camera and learn what its features are, what they do, and where everything is located on your camera.

The more time you properly train using the camera manual and your camera body the less time you will spend in frustration and producing poor astrophotographs.

Astrophotography Session Checklists

1. Plan what days and/or nights you will want to shoot the sky. But don’t cut yourself too short on planning time for each session, as “haste makes waste” definitely applies to our pursuit of astrophotography at sea and ashore. Try to plan the day before an event so you are not hurried and have time to sort out any issues that may arise. Try to visualize the event as well so you have a clearer idea of what you want to do.

2. Check the weather. If the main deck is closed due to weather, go out on another deck. If an upper deck is roped off, usually due to high winds or maybe ship’s maintenance, DO NOT use that deck. For safety the captain may make a decision to close decks based on weather or other circumstances. Whether you are in port or at sea you have to know what the weather – here on Earth as well as in space (auroras) – is going to be doing during the day or night time period you are interested in doing astrophotography. In Chaps. 3 and 4 we discussed doing this as well as the next item.

Ship Tip

Don’t give up on the sky due to weather. Even if the weather is predicted to be cloudy and rainy go on deck and check for yourself. There could be rainbows and moonbows present, distant lightning. Partly cloudy skies can afford beautiful sky shots with stars peeking through the clouds as well as auroras, the Moon and who knows what else. Days at sea are rare in our lives, so we have to make the most of them that we can. Even if there has been persistent rain, you can occasionally check to see if it is letting up.

3. Determine the ship’s. position and local time zone. You have to know these in order to properly use your astronomical software, planisphere or star charts. This is really a critical item but easy to determine as we have discussed previously in Chaps. 3 and 4.

4. Decide what you will be photographing. If you made your cruise list of astronomical objects of interest in advance you know what you will be photographing each session. If the Sun is your object of interest read and make sure you completely understand solar safety in Chaps. 5, 10 and 13.

You will need to double check your list against the ship’s actual position and local time to make sure that there have been no changes. Consult your astronomical software, planisphere, and star charts to know what time and where the object will be in the sky and where you will need to be on the ship to photograph it. After doing so, go back and review the camera settings and advice given you for the type of astronomical object you want to photograph in your session. You might even want to write these down so you have them available topside for reference.

During the day or well before your planned session check your camera and equipment while in your stateroom. You will have to remove your tripod from the backpack or lugage you transported it in and prepare it for use. To avoid a severe pinch injury, when spreading the tripod legs keep your fingers and hands away from the very top of your tripod, where the three legs engage the three mechanical locks (personal and painful experience talking here). When closing the individual tripod leg segments be careful to keep your fingers clear as this is another finger pinch possibility. The best way to close each of them is to use your hand on the footpad to push them closed after unclocking each segment.  Failure to do these following checks each and every time that you use your tripod could result in your tripod collapsing and injuring you or others and damaging your camera and lens. Here are some other things to check:

Did you read and understand the tripod user’s manual?

Check that the mechanical lock that holds each individual tripod leg in position is fully engaged. If it isn’t, the leg will move freely and the tripod cannot be set up.

Check that each tripod leg segment is fully extended and locked.

Check that tripod leg footpads are fully screwed in so they can be adjusted as needed.

Check that the tripod head that you will be using is securely fastened to the tripod. Be careful during use not to unscrew the tripod head while making azimuth adjustments to it.

If you have a tripod adapter plate attached to your camera body is it tight and properly aligned?

Fully extend the tripod legs (watch where they go as you move around!) and sitting on your bed or couch (in case the camera falls) attach your camera to your tripod. Make sure it is properly seated and secured.

While holding the neck strap tug on the camera to verify proper attachment to the tripod. During your astrophotography session occasionally check visually and with a slight push on your camera (while holding the neck strap) to make sure it is still secure.

The tripod adapter plate can loosen on your camera during a session, so check periodically to make sure that that your camera is securely fastened to the plate.

If the Sun is your object of interest, do you have your approved and certified solar filters for each of the lenses and optical aid you will use? Do you have your approved and certified ISO 12312-12 solar glasses?

Are your camera batteries fully charged?

Is your smartphone or tablet fully charged?

Is your astronomical software, planisphere or star charts properly aligned to ship’s date, time and position to help you find your object of interest?

Are your lens filters, or lenses if you have no filters, clean, with no major oily or particle deposits?

Is your headlamp working, and do you have spare batteries?

Is your camera memory card in place and does it have sufficient storage for new astrophotographs?

Attach your shutter release and verify operation.

Take test exposures using different settings to insure all camera functions are operating properly and delete exposures when completed.

Are all of your lenses and accessories packed and secure in your zipped up and closed camera bag/backpack?

Are you dressed appropriately for the weather topside? Take a jacket, hooded if you have one, for “light reduction” purposes.

Ship Tip

On the upper decks there may be large deck lounge towels and blankets available to use as a light block for your camera. You can use towels (they are lighter and easier to handle) to form a light shield around your lens when needed. This works well to block excess ship deck lighting.

5. Go topside. Check out the ship the day you get aboard to become familiar with the layout of the ship and decks as detailed in Chap. 3. Also do that on the first night aboard to see where the light and dark zones are. Do a final checkout of the area where you will be setting up during the day, prior to your session, to see if there have been any changes to the area. Familiarize yourself with the layout, the lighting conditions and where specifically you will set up your tripod or brace against the ship.

Before heading out for your session, before leaving your stateroom make sure:

The tripod has been checked according to the tripod safety note.

The tripod legs are pushed together for easy carrying.

The camera is securely attached to the tripod.

The camera neck strap is wrapped around your hand and your other hand is free to use.

The camera bag/backpack is closed and secure.

Ship Tip

Have consideration for a “significant other” or roommate, neighbors. When getting up at all hours of the night go to great lengths to try and not disturb others. Lay out clothes and equipment where you can get to them quietly – no opening closets or drawers.

Stay in red light mode only (including in the bathroom) as soon as you get up, while retrieving the headlamp from the night stand. Take camera/tripod and camera bag/backpack. Make sure you have your stateroom key card with you.

Do not allow the stateroom door to close on its own, as it will be loud when it shuts. Close it and give it a tug to make sure it is closed. Make your way to your topside location and set up.

6. Dealing with dew. When you take your air conditioned camera gear out of your stateroom and up on deck day or night, be sure to check for condensation on your lens by shining your red headlamp on it. This dewing will happen in a warm, humid environment. If it does the best way to get your camera and lens acclimated and clear is to see which way the wind is blowing and hold your lens into the wind with the lens cap off. It won’t take very long for the lens to clear, unless you are in a dripping humidity condition. This method will still work, but it will take longer.

Once you have cleared your lens, you also want to make sure that the viewfinder, your mirror and sensor are clear by looking at each of these components. Looking through the viewfinder at a distant ship’s light will help you see if the prism or mirror is dewed. You can put the mirror up to see the sensor or take a quick time exposure to check for fogging from dew.

In the most extreme conditions – with your camera in a very cool stateroom for a good length of time before going up to jungle-level humidity – you are looking at more minutes than usual to get everything clear. Don’t put yourself in the spot of losing a shot that is time critical, like an ISS/satellite pass or eclipse events because your camera is fogged up. Build check out time for dew into your session schedule.

Once they have been acclimated your lens or camera should not fog up on you. If it should happen, use the wind to get them clear.

7. Setting up your tripod . First, this warning: Keep your fingers and hands AWAY from the very top of your tripod, where the three legs engage the three mechanical locks when they are spread. It is very easy to pinch yourself if you are not careful.

Set your tripod up so all three legs are fully spread. Verify by a slight tug on each and visually inspecting their deployment.

Make sure tripod footpads are even on the deck, with no wobble.

Verify the sturdiness of your tripod set up by placing both hands on it and exerting a small amount of force. The tripod should not move.

If your tripod can be adjusted for height, set it to the height you desire, making sure that each segment of the tripod legs is fully extended and locked.

Ship Tip

Wind and motion in the ocean can limit your tripod height. The higher it is the more affected it will be by these factors. Don’t overextend! This is especially true if you have center column segments that can be raised.

7. Finding Your Astronomical Object. If the Sun is your object, read and make sure you completely understand solar safety in Chaps. 5, 10 and 13 before you proceed.

Astrophoto Tip

The LCD screen, if you have one, and the viewfinder are your interface between the sky and your camera. (If your camera has Live View, it will send the actual lens view to the control panel LCD screen.) You will use these to find, frame and focus the astronomical object you are photographing. As you input your various settings of ISO, exposure time, f/stop, file type and size, etc., your LCD screen and viewfinder should update to show your settings.

From your planning session you should have a good idea where your astronomical object of interest is located. Try to let your eyes get somewhat dark adapted if you are shooting at night and are in a more or less dark spot on the ship.

Your astronomical software on your smartphone or tablet might have a ‘Night View” feature that uses red light to show your device’s screens. If so, use it. Try to block any remaining light sources from getting into your lens. The lens hood should help if you have one.

Find your object and confirm with your software, planisphere, or star chart.

8. Focusing your camera. This is the foundation for the outcome of your astrophotograph. You can have perfect settings, but unless the focus is spot on you could end up with “focus fuzz.” How you focus depends on:

your camera type.

what your camera and lens manuals say about focusing.

the brightness of the astronomical object you are photographing.

whether it is night, full daylight, dusk or dawn.

Here are some general guidelines:

During the day, if your camera has “Autofocus,” you can probably use it.

If it is dusk or dawn your camera may be able to Autofocus on the visible sea horizon . If your object is too dim, and you can’t see it in the viewfinder or in Live View (if your camera has this feature), use the most distant and dim light on the ship (trying to preserve night vision) to focus your camera. You can use the viewfinder or the Live View (with zoom if you have it) to get a sharp focus. You want your lens to be focused at infinity, as all of your astronomical objects will be at this focus setting.

If your object is bright, use the viewfinder or Live View with zoom to focus. A bright star or planet can really help get a sharp focus, as can the Moon.

Astrophoto Tip

The infinity focus mark on your lens may be a bit off. Try to confirm with each of your lenses exactly where infinity focus is. You may want to have a small piece of clear tape to hold your focus if you are going to be shooting a lot of astrophotographs at night, as you can move the focus.

9. Align the camera with your astronomical object. Unless you were able to focus in place, pick up and align the tripod so that your camera is square on to your object. Make sure the legs are fully spread and be careful in moving around your tripod so that you do not trip over the legs.

Get behind your camera and place a hand on it. Unlock the tripod head so it can move in altitude and azimuth, taking care that the camera does not fall over vertically when the altitude locks are loosened.

From the rear of the camera do a rough line of sight alignment using the top of your camera. Then look through the viewfinder and Live View at your object. If your object is visible get the frame position you want and then tighten your tripod head locks. If it isn’t visible then you will have to take an exposure to verify frame position and adjust as needed.

Ship Tip

Take a seat! Use an available deck chair or deck lounge – if you move it replace it when you finish – while you are doing your astrophotography session. It will be more comfortable and put you more in line with the camera for pointing, composition and taking the exposure. This is great fun if your object is high overhead; you will feel more like you are doing yoga rather than astrophotography. Maybe you will be lucky and have a LCD panel that pulls out and can swivel for viewing adjustment – one feature Nikon didn’t do on the D810a, unfortunately.

10. Choosing your Initial exposure settings. We have tried to include camera settings that have worked for each type of astronomical object that you will encounter and photograph at sea. When available we have included photographs of such objects along with the settings used to create the photographs. It is recommended that you use these initial settings for the first astrophotograph in your session. Then you can SAAS as you progress in your session.

If your camera has the ability (Rule 1) to take “RAW” photographs do so, as the resulting image will be pure, with no compression. This allows the greatest flexibility in photo processing. These files can be large – 70+ MB – so make sure your memory card has the storage capacity.

11. Take your exposures. Once all of the foregoing has been accomplished take your exposures. After you take each shot you will assess it using your LCD screen, if you have one. If not, shoot several shots with varying exposure times and ISO settings. Then, if need be, you will update focus and settings and take shots until you get the one you like – Rule #4 at work here.

If you have to move to a different location for a new object, just follow the steps again.

Ship Tip

If you notice that there is motion in the ocean showing up on your pictures, and you have already used ISO and shutter speed to compensate, try the following.

You can further reduce ship motion by shooting your pictures as close to the ship’s centerline as possible. This minimizes the ship’s sideways roll. Being on the main deck further reduces the ship’s roll.

If the ship is heaving up and down, and you are shooting short exposures, you may be able to time your exposure while the ship “pauses” at the top or the bottom, especially if you are at the halfway point of the ship’s length.

It’s worth trying these before you give up on your astrophotography session due to motion in the ocean.

12. Ending the session. When you are done put the lens cap back on, turn off your camera, set down your camera and tripod, kick back and look at the sky. You never want to miss a chance to SEE the sky with your own eyes and take in the sea that surrounds you.

Make sure you have all of your gear by looking around with your headlamp. Secure your camera bag/backpack, and head below for a well-earned rest. You may want to process your astrophotos right away or after some shut eye.

© Springer Nature Switzerland AG 2018

Gregory I. RedfernCruise Ship Astronomy and AstrophotographyThe Patrick Moore Practical Astronomy Serieshttps://doi.org/10.1007/978-3-030-00958-8_17

17. Taking What the Sea, Sky and Ship Will Give You

Gregory I. Redfern1 

(1)

NASA JPL Solar System Ambassador, Ruckersville, VA, USA

Hopefully you are reading this book before you go on a cruise with astronomy and astrophotography on your agenda and before you take your first astrophotos. Why? Because you need to know how special this pursuit of ours is beyond the technical aspect of photographing the sky. This chapter purposely appears before the chapter on how to process your astrophotos because after you read it you will gain a much larger and deeper appreciation for your results. We will also show you why it is the foundation for Redfern’s Rule #10.

Each astrophoto you take captures an instant of time in the life of the universe as well as your own – a co-mingled preservation of a moment that will never be again for you or the universe. At the precise moment that you open your camera’s shutter photons of light from the universe enter your camera’s lens and fall upon its sensor, which is made of atoms that came from that very universe you are photographing. The atoms that make up you and the planet also came from dead stars that exploded at their end of their lives; from the merger of neutron stars to make gold and other rare elements. From an amorphous cloud of gas and dust composed of elements from these dead stars’ lives and deaths – all co-mingled into the Sun, the Solar System, humanity and ultimately each one of us.

We have developed the technology that anyone who has a desire to do so can capture images of the universe itself. This can be done simply or it can be done at a level that is sufficient to qualify as astronomical research worthy of professional publication. People can photograph the universe with their smartphone or tablet they carry or spend tens of thousands of dollars to build a capable observatory. All of us are guided by our own reasons for doing what we do – a pretty picture or a dataset.

Humanity is directly connected to the universe, and we as a species have lost sight of that connection for the most part. We get caught up in our daily lives and respond to the pressures of modern living as well as what happens to us personally, be it ourselves individually or our family and friends, city, country, planet. Our focus is trying to make a living, getting through life as best we can.

This is the state of humanity since Homo erectus . The only thing that has changed is that we are far more sophisticated in our quest for food, shelter and survival. We have also been able to sail the waters of Earth and explore the Solar System in person and by robotic spacecraft. Our eyes have given way to huge telescopes on the highest mountaintops and in space to explore and record the universe at large. But for all of this technological innovation from our machines a lot of us still are in awe from what we see of the universe through our very own eyes – and for those of us who chose to do so – our cameras.

Millions of people around the world want to learn more about the universe from which they came, live in and are part of. Stories and astrophotographs about our universe, via newspapers, television, radio, and the Internet abound. People really do want to know about the universe.

The first lecture I give at sea is always “So, You Want To Be An Astrophotographer?” The reason is simple. To tell cruise guests they can take pictures of the sky while they are at sea. Some take up the challenge. So, it seems, have you. Taking astrophotos on a cruise ship or perhaps some other vessel like a sailboat, has challenges no other astrophotographer on land has to contend with – the sea.

You and I, along with others who take up the challenge of taking astrophotographs at sea, are a definite minority in the world of astrophotography. My wish is that their ranks will swell, and perhaps, just perhaps, people will find the passion that can come from every photon of light collected while at sea.

People go on cruise ships for a lot of reasons. Most of them must enjoy being on the oceans and seas of our planet, or else they wouldn’t be on a ship. But once you get beyond the routine rhythms of cruise ship life there is something much more satisfying, primal almost, awaiting those who seek to find it – being one with the sea and sky.

Scientists think that the waters of our planet perhaps came from geological processes such as volcanoes or extraterrestrial ones such as impacts of asteroids and comets, or a combination of both. All of these forces of nature can produce a lot of water. With the leading theory of how our Moon formed that you learned about in Chap. 9 it is thought that Earth’s oceans might have already existed then and survived the impact. Who knows if we will ever truly know the full legacy of the waters on which we cruise.

One thing that is for sure. These waters are a direct link back through time to the very beginning of our universe 13.82 billion years ago – the Big Bang – which you learned about in Chap. 2. The primordial hydrogen created in that event led to the very first stars, supernovae and chemical elements, including oxygen. Water became common in the universe and in our Solar System, including here on Earth.

When we embark on a cruise we set sail upon the oceans and seas of our planet that trace their origins, as do we, to the Big Bang. We will see our star the Sun, the Moon, planets and stars in the sky. The visible line that separates the two entities of sea and sky – the horizon – is our portal to these realms that we see all around us.

While at sea we can view the horizon we are headed towards and the one we have left behind. When the onset of night comes Earth’s shadow beckons us to the east while the remains of the day sets in the west. What will be our companions for the night rise from the sea to greet us while others slip from our sight into the sea. It is here, in the choreography of night that is witnessed from a ship at sea, that one can develop a keen awareness and yes, even a passion for being part of it. And capturing a moment of it.

Astrophotography is done for science, art, profit, hobby and passion. For hard core astrophotographers it is the passionate pursuit of the technically perfect picture by capturing photons from an astronomical object. These pictures can also be used to educate and entertain people while learning about the universe in which they live. The old adage that “A picture is worth a thousand words” is certainly true here.

Each image taken represents the culmination of a significant effort to obtain it. Each image also represents a snapshot in the life of the universe and yourself at a precise moment in time and space which will never be repeated – in other words, unique in all of the universe.

There is far more to it than just the picture aspect. Observing and photographing the sky at sea, more than anywhere on land, brings a more surreal experience. This may be due to being in an environment that, with the exception of the ship herself, has no other reminder of earthly bounds. In the dark of night away from ship lights, there is only the blackness and the smell of the sea that accompanies you as you contemplate the star-filled sky.

Your ship-observatory is from where you will meld with the sky by eye and by camera. It is where you have to start to learn how to “Take What the Ship, Sea and Sky Give You,” good ol’ Rule #10 . The meaning behind Rule #10 is that at sea, more than anywhere else, you have to make the most of the conditions you are given during any visual or astrophotography session.

Now that you have absorbed some philosophy of our art let us give you some practical advice you can use to get the most out of every session at sea.

Every single cruise ship at sea, even those in the same class, is different. One captain may have minimal deck lighting while another will be at ‘Full Dress Ship,” with lighting extending overhead from the mast to the forward part of the ship’s upper decks and stern. That is the toughest lighting condition to overcome, but not impossible.

If you encounter a “Full Dress Ship” condition or a ship that is brightly lit up you need to determine if you can get forward of the lights on the uppermost deck. These “Dress Ship” lights (light bulbs) are strung out to hang so that they end before getting to the ship’s forward mast light. They also cannot provide lighting forward of the bridge while underway, as that would interfere with the safe operation of the ship. Can you access the bow, the area forward of the bridge?

If you can’t you can still try one other possibility. On some ships the uppermost deck only has open deck railing, while others have a complete glass/steel structure (Figs. 17.1 and 17.2) that is supported by steel frames, some of which are angled. On the open deck it is easy to place your camera forward of the lights and act as a light block by standing directly behind your camera as it faces forward towards the bow or off to the starboard or port sides.

Using the glass/steel structure you might have to take the camera off of the tripod, wrap the neck strap securely around one hand and support the camera body on the very end of angled steel frame or on the steel flat top of the structure. This glass/steel structure will go across the entire deck and have a connected glass/steel structure on the port and starboard sides that go aft a good portion of the top deck.

These pieces of ship structure are wide enough to easily support the placement of your camera. The angled steel support can come in very handy when there is light around on the uppermost deck as you can use the very top of the angled steel support to point the camera in the sky towards your camera subjects. These angled supports are located on the port and starboard sides as well as along the structure as it crosses the entire deck. Find the one angled support that is closest to being directly in line with your object of interest and take a test exposure to see if you are spot on. You can use your other hand under the camera body to get a bit more altitude if you need it.

Similarly, you can also use the flat steel support that crosses the entire deck and on both the starboard and port sides to take pictures of objects that are dead ahead and need no altitude adjustment. You only have to rotate your camera in azimuth to get your desired object centered if it is low enough.

Ship Tip

If there is a lot of motion in the ocean you may be able to minimize it by shooting using the support closest to the ship’s centerline.

Fig. 17.1

Angled steel support. (Image by the author)

Fig. 17.2

Flat top steel support. (Image by the author)

Ships that have open bow access at night – usually the very large ships that have a helicopter landing pad on the bow – are great. Man, if your object of interest is accessible from the bow you have it made. It will be dark except for the possible projection of the ship’s running lights into any mist or water vapor.

Windstar Cruises has decks accessible at night that allow full view of the bow from port to starboard a few decks above the main deck. These are great cruise ships for astrophotography.

The stern is a great spot for less lighting, as we have discussed before. If the ship has food and bar facilities there they may be totally dark after operating hours. The stern with the ship’s wake is always an added bonus.

The ship’s centerline from the bow to the stern is also where you may be able to minimize ship roll, as she will probably roll about an axis that goes through the middle of the ship. But what if your shot is on the starboard or port side? What if the ship is pitching up and down?

Lighting, ship motion, superstructure layout – how do they affect the object(s) you want to photograph? This is where you have to assess it all with regard to the ship, compare it to what you want to see/photograph and then go to the next evaluation step – the sea.

The only consideration you really have to make about the sea with regard to your astrophotography session is its state as you begin and as you proceed to the end. Is it calm, is it active or, as described, is it an arcade ride? Ironically, your visual observing sessions are not affected at all by the sea unless the decks are closed for safety considerations or you yourself are affected by motion in the ocean.

Ship Tip

If you are worried about motion sickness visit your personal physician before your cruise or the ship’s Medical Facility if already aboard. Medicine has come a long way in helping to prevent and ease the effects of motion sickness. There is a patch you can wear and other options.

The condition of the sea determines the motion of the ship. Most cruise ships are equipped with stabilizers that help to lessen the motion in the ocean, and they really do work. Captains also want to minimize motion in the ocean, so they do all they can to avoid a full gale and anything else that might even get close. But try as they can they cannot eliminate all instances of motion in the ocean.

But if the seas are active and there is a good wind blowing you have to assess their impact on the ship and your session. It very well could be that an astrophoto session is out the door, but some great wave photography might be in store.

With time and experience you will be able to tell from the sea state forecast on the ship’s information channel as well as your own assessment how the sea will affect your ship and your planned astrophotography session. There will be only one more consideration – the sky.

For the sky it is a combination of weather forecasts and actual visual assessment of conditions. What will be the cloud cover, the wind, the precipitation chances, lightning? Each one of these has a different impact on your astrophotography session, and they sure can be present together to make things real interesting.

As said earlier, it is only when it is raining that you should consider an astrophotography session, forgive the pun, a washout. Even if not raining total cloud cover can cause a “No-Go” for a session. Partly cloudy is a different story, as cloud breaks can offer some photo possibilities. Double cloud layers make it tough, too, as you may have some patchy, low clouds but overhead there is a total blanket.

Wind is the biggest factor, as the sky can be crystal clear but a howling wind can unsettle the sea to make for that dreaded motion in the ocean and make it near impossible to get a shot, even with a tripod. High wind can also make it difficult to move around on deck, especially the upper decks. You can shoot astrophotos in the wind, but you need to find wind breaks to do so.

Besides the structures previously described on the uppermost deck of some ships, there are also other areas on the uppermost deck, usually near the sport court or sunbathing areas, that have steel/glass structures that provide protection from the wind. You can use them on occasion to get shots that you could not have otherwise.

Because you won’t be using a telescope, “twinkling stars” is not a concern of yours at sea. In fact, it might be better in terms of having a really great astrophoto session. Why? Because twinkling stars usually mean a crystal clear but turbulent atmosphere following a storm. The clouds have moved off, but the upper layers of the atmosphere are very unsteady due to winds, and this causes the brighter stars to twinkle. To the eye and camera lens it makes for a pretty addition to our astrophotos, but in a telescope the twinkling – the unsteadiness of the atmosphere – gets magnified to the point where you almost can’t make anything out. It is like trying to look at the reflection on a body of water when it is full of ripples – a no-go. Astronomers call this quality of the steadiness of the atmosphere “seeing.” It is sometimes stated as a number from 1 to 10, with 1 being the worst and 10 the best. Again, this really only applies to using telescopes.

Rule #10 takes the ship, sea and sky into consideration at the very start of a planning session and is continuously updated even if the initial assessment is a “no-go” or “perfect.” This assessment continues while an active session is ongoing, as any of these factors can change in very little time, so you have to do this. You can have clear skies and moments later a rain squall can sneak up on you with little warning while all of your gear is out on deck. Be prepared for that by placing a lounge towel or your jacket on your camera to protect it. Squalls can get fast and furious, dumping a lot of rain in very little time, so always be aware of where you can go quickly for shelter.

Here’s a safety note: DON’T run on ship decks, especially when they are wet from rain, snow, ice, dew, or a freshwater wash down. THEY ARE SLIPPERY!!! Wear shoes appropriate for onboard ship and take smaller steps when the deck is wet.

If you wanted to do an astrophotography session but got clouded or rained out or the weather was forecast as such, you can get up in the night regardless of the forecast to see if it is clear. You can look out your stateroom window or verandah if you have one, go to the main deck or uppermost deck to walk around and see what conditions are. If it is raining that will be pretty evident, but the percentage of cloudiness usually needs a 360-degree look. Unless it is raining you should go all the way to the upper deck for a look.

Besides checking the weather, this is a time when you can try and be one with the sea and the sky. The ship is quiet, deserted almost, topside, and a dark spot is rather easy to find. Pause for a few moments before you go below to get your gear or to turn in. Times like these, when it is just you, the sea, the ship and the sky, are fleeting – and precious. Make the most of them.

© Springer Nature Switzerland AG 2018

Gregory I. RedfernCruise Ship Astronomy and AstrophotographyThe Patrick Moore Practical Astronomy Serieshttps://doi.org/10.1007/978-3-030-00958-8_18

18. Process, Print and Post

Gregory I. Redfern1 

(1)

NASA JPL Solar System Ambassador, Ruckersville, VA, USA

Processing your astrophotos does not have to be complicated. As you will see you can go simple or up to serious in terms of money spent and capability gained as a result. There are whole books devoted to processing astrophotographs, and at some point you should read them. But to start out you can use the information provided in this chapter to get some very gratifying and beautiful results you will want to keep and share with others.

As you prepare to process your first astrophotos you may want to start an astrophoto logbook that details each shot you take. Granted it is tedious if you try to keep written track of each astrophoto, like astrophotographers did in the days of film. Nowadays, with digital, it is almost downright impossible to log in the very large number of shots you take in one session. Not to worry. Let your camera and computer do the work for you.

With a digital camera, each time you take a shot there is a lot of information stored in the shot’s metadata. This should include date, time, file number/name, ISO, lens used, exposure time, f/stop, and other useful settings. This metadata is easily retrievable when you access the photo using software, either camera brand proprietary or third party. This can be software that processes and/or views your photos. There will be an Info button that you click on that will display the metadata for that shot. If you leave the Info button active it will provide info for each shot as you go through your photos.

The information provided here is based on the Mac operating system. For PC users you should be able to do the same thing.

For each photo session you can create a folder that is named for where and when you took the photos contained in the folder. At sea you can use the name of the ship, as each of the photos in the folder will have their respective dates in the meta data. Because of the length of a cruise it makes more sense to have just one folder containing all of the astrophotos from that cruise than an individual folder for each session on that ship. If you do a one-night only session then the location and date can be used as the folder name.

If you are using a digital camera other than a smartphone or tablet, your camera will probably have a removable memory card that is inserted in the camera to record all of your photos. You may want to keep the memory card for each cruise that you take, so you will have each picture that you took on the cruise separate from your computer. This is a good way to preserve them if you don’t have a backup system or Cloud storage.

The cost of memory cards has gone way down in price, so this wouldn’t necessarily be cost prohibitive. You can back up your photos to an external hard drive and so be able to retrieve them in case of computer catastrophe. You will definitely get attached to your astrophotos and will want to keep them.

Astrophoto Tip

DO NOT delete your cruise astrophotos and regular photos from your memory card until you get back home. You want to insure that you get a good download of your pictures plus any back up that you hopefully use, like the Cloud or an external storage device.

The same applies to smartphones and tablets, except they use their own internal storage, and you download pictures either by email or hardwire transfer to your computer. It is recommended that you use the same folder protocol described earlier to keep track of your smartphone and tablet astrophotos. Once you have established how you will document and preserve your astrophotographs it is time to decide how you want to process them.

The good news is that with your astrophotos you do not need expensive or complex software programs to process your pictures. The photo processing software probably included on your smartphone and computer as well as Nikon’s (or other camera manufacterer’s proprietary freeware or software can be used to process all of your images. You be the judge on their quality from the pictures you have seen in this book.

This doesn’t mean that you can’t get into more sophisticated (and expensive) software for processing. It just means that you can get very satisfactory results with what you should have available on your smartphone, tablet and digital camera while you are learning the ropes of astrophoto processing.

Some smartphones, tablets, pocket cameras and DSLR’s may have in-camera image processing capability that you can use (Rule #1). You could process the photos in your devices or camera and then download them to a computer for retention. If you do not have a computer or other processing capability then this is the way you have to go.

Astrophoto Tip

The Nikon D810a (and possibly other cameras) has some features that can be used for taking a shot that require processing the resulting image using that camera – Rule #1 and #2, because the necessary tools are not in your normal image processing software. On occasion you may use these shooting features and process them using the camera. You can then download the camera-processed photo and can possibly use your ordinary image processing software. Try it to see if it works. 

If at all possible download your astrophotographs from your smartphone, tablet and/or camera to your computer for processing. If the memory card can be removed from your digital camera and placed into a compatible external slot this is a fast and convenient method. Astrophotos downloaded to a computer for processing using software that came with your computer, your camera’s proprietary software or a third party software program, is far easier to do than in-camera or device processing.

The reason is that you have a much larger and brighter display screen for viewing and processing your astrophotos, which is essential when viewing dim objects. Also, your computer will have much more computing capability than a smartphone, tablet or digital camera. Processing RAW astrophoto images that can be as much as 70+ MB each can tax an operating system when you start making adjustments.

The first thing to do with the astrophotographs you have taken after a session has ended is to take a look at them. You can look at them on the camera’s LCD first before you download them, but you will get a much better view of them using the computer’s larger and brighter screen.

Astrophoto Tip

Make sure your computer screen’s brightness is at maximum and the angle of the screen is adjusted to your eyes to get the most visibility. Work in total darkness or as dark as you can make the room so that no reflections are on the screen and no background light can affect the view of the image on the screen. Try this for yourself – look at an image on your screen in a brightly lit room versus in a dark one. We still need a “darkroom” even in the digital age.

You may discard some astrophotos during this screening, if it is readily apparent that you have better exposures. But do not do this until you develop an astrophotographer’s eye (an acquired skill that comes with time and experience that allows you to know what to keep and what to delete). There may be details in an image that you can bring out by processing them. With that said, there may be some pics that you don’t need an astrophotographer’s eye to know they aren’t worth keeping.

When first looking at each astrophoto check to see:

How bright the image is. Can you barely see it when compared to others that may be brighter? You can probably increase the image exposure using your software and then compare to others to see if it is worth keeping.

Is the composition correct? Is your object in the frame where you want it to be or is it cut off? If the image is tilted, you can probably straighten it using your “Crop” adjustment.

Is the focus sharp? If your processing software can “Zoom in” to give you a larger view of the image do so, and see if it is sharp, soft or fuzzy. Compare to others in the same way.

Are there excessive “EKG” lines in the photo from ship motion or wind? Are any images better than others in reducing or eliminating these squiggles?

Does the white balance seem right? Is your background sky an appealing color or is it artificial?

In a series of shots of the same object, is there one that seems to be better than all of the others?

Again, your purpose in doing a “first look” at your astrophotos is to weed out any really bad ones and try to find a “best one” or two that you can concentrate on regarding processing. Consider yourself lucky if you get 1 or 2 good astrophotos out of 20 to 25 shots on average. And to be honest, it usually is often the first shot that is the best. But Rule #4 presides, so take a lot of astrophotos.

Astrophoto Tip

Be careful not to declare ALL of your astrophotos as being worthless from your session, as you would be surprised at how processing can pull something out of your images. Stick to the first look screening process by selecting the “best of the worst” to work with. By doing so you will maybe get something worth keeping, and more importantly you will learn from your mistakes and gain valuable experience of the whole sequence of setup to processing.

As a corollary to Redfern’s Rules of Astrophotography, specifically Rules #1 and #2 , you will want to apply those rules to the image processing software that you will be using. You have to know how to use your image processing software in order to get the best astrophotos you can from your imaging sessions.

If you have been using “regular” image processing software, i.e., not astrophotography specific, use what you know. The only true difference in taking astrophotographs at sea from regular at-sea photographs is your subject – the universe as opposed to planet Earth. Always remember, with an astrophotograph taken at sea you are dealing with a digital image that is processed just like any of your other images.

Let’s face it. Our astrophotographs taken at sea are not going to be used for scientific analysis or research. Unless you capture a supernova outburst, an extraordinary unidentified flying object (UFO), or other transient phenomena that might be of interest – more on that later – our astrophotographs taken at sea are for our enjoyment.

Accordingly we do not have to use image processing software that is necessary for scientific purposes – and there is image processing software that is an absolute requirement for astronomical images used for research and analysis. If you progress in your interest in astrophotography when you get ashore, as we discuss in Chap. 19, you may need more sophisticated software.

Nikon image processing freeware is used in conjunction with the Nikon D810a astrophotography DSLR. It is image processing software designed for Nikon DSLRs and Nikon’s RAW format. It is used to process regular photographs taken with Nikon DSLRs but has an “Astro Noise Reduction” tool specifically for astrophotography. This tool helps reduce noise from longer exposure astrophotographs, and it works.

We can’t list here all of the image processing software that is available, but there are some common features they all use. See if the software you choose allows for adjustments via a “sliding tab,” input of an expressed value, clicking on values and changing “x and y” graph values – all of which lead to changes in the astrophotograph.

The majority of what your processing efforts will try to adjust in your astrophotographs will center on trying to make your image(s) brighter, have more contrast, have a pleasing sky background and have as much detail as possible. There are tools in image processing software that allow you to do this, and you will have to know and work with your software to learn them.

After you accomplish your “first look” and hopefully have narrowed down the number of RAW images to work with, you can start on increasing the brightness of the image. This can be done by adjusting the exposure, brilliance, contrast, shadows, highlights, brightness and black point values – or similar tools in your image processing software. You really have to start at the top of these tools and work your way down. You can play with one tool to get the image to where you like it and then move on to see how you can improve the image with the next tool. Go back and forth until you think you have the best and brightest image you can get.

Then you can play with the White Balance, which is really a critical tool that determines what the overall “color” of your image will be. Your camera will probably have a White Balance setting that you can use for your initial shot. Try using “Sunlight” or “Auto” and see how your images turn out. You want to have an eye-pleasing sky background that is not too brown or blue. Your developing “astrophotographer’s eye” will tell you when you have it right. This tool can make or break an astrophoto.

You can also make color adjustments, but remember Rule #9 and keep the color real. You can even take color astrophotographs and make them black and white if you think it adds an aesthetic touch to the shot. This is most powerful as an option when you have a lot of stars or when the color version of your astrophotography is not so hot. Try it and see if it works with such an astrophotograph (Fig. 18.1).

Fig. 18.1

Object viewed: Large Magellanic Cloud & Tarantula Nebula. (Image by the author)

Exposure: 5 minutes

Comment: This land-based astrophotograph in black and white seems to herald back to the day when astronomers used black and white glass plates and specialized film. 4-inch refractor telescope with astronomical CCD

Your software may also allow you to make adjustments for lens type, cropping, image rotation and file conversion. This nifty tool takes your finished (and large) RAW image and converts it to a JPEG or other file type.

Astrophoto Tip

Depending on your image processing software and the processing power of your device or computer, make sure that the single adjustments you have made with one particular tool are fully made before proceeding to the next adjustment or tool. Image processing a large RAW file can take some time before an adjustment is completed. If you try to do too much at once without allowing for single adjustments to be made you might freeze your computer or get an incomplete result. Your software may provide a means for you to know when this has been done or it may rely on the change to the image made by the adjustment to let you know.

As an example of the processes just discussed I took one of my early (December 2015) and not all that great astrophotographs taken in the Southern Hemisphere while underway on Nautica . It was not a particularly good night, but it was the first cruise I had been on where I was able to see new sections of the Milky Way, the Large and Small Magellanic Clouds. So I made it a point to photograph them every chance I got regardless of the sky conditions.

I had taken a series of photographs and went through my “first look” process. As you can see in the original RAW image it was not the best – dim, lens flare, unpleasing White Balance. In this photograph I had to use a high ISO setting, which can introduce noise. I purposely processed this image using the Mac OS “Photo” application, which can process RAW images, to see how well it would perform. Considering the quality of the RAW image it didn’t do too bad (Fig. 18.2a and 18.2b).

Fig. 18.2a

Object viewed: Milky Way, Large and Small Magellanic Clouds. (Image by the author)

ISO: 5000

Exposure: 10 seconds

Lens used: 14 mm f/2.8; tripod mounted

Comment: RAW image before image processing

Fig. 18.2b

Object viewed: Milky Way, Large and Small Magellanic Clouds. (Image by the author)

ISO : 5000

Exposure: 10 seconds

Lens used: 14 mm f/2.8; tripod mounted

Comment: RAW image after image processing

The image was cropped to eliminate lens flare at the upper right and lower left. Edit tools were used to brighten and enhance the image and then noise reduction applied. The finished RAW image (76.7 MB) was converted to JPEG (987 KB)

As you can see, even with a “bad” RAW image you do not want to give up on it. Images such as this are very useful to document the effect of sky conditions on your images as well as your progress in taking astrophotographs and processing them to get that astrophotographer’s eye.

Your software should also allow you to return your image to its original state so you can start over again. “Batch processing,” which uses one image’s saved adjustments to process several images at a time with those saved adjustments usually does not work for astrophotographs. This happens because each image is really unique and needs to be processed individually.

It take time to process images. When you are satisfied that you have the images you want to keep, make sure the file names are correct and in the proper folder. It takes discipline to do this on a regular basis, but if you don’t it won’t be long until you can’t find that “one-in-a-million” shot that you got and is now somewhere among 16,000 images on your computer.

Now that you have your images, you can consider printing them out. Some cruise ships have photo shops onboard that may be able to print out your images for a fee. You can also wait until you get back ashore. With today’s printers and printer photo quality paper you can print out very nice end results. You want to use the highest image quality print out and use glossy paper.

You can also have the best of your astrophotos made up into large wall size canvas-type prints for display by sending a high quality and large size image file to a store that does such photo processing. The specific file requirements needed to do this are provided by the store’s online website. You go through the downloading and order process and before you know it you have that print you love on your wall.

If you want to share your astrophotographs with the world it is certainly possible to do so. With social media being what it is today it is possible to post your astrophotographs online and be seen by literally thousands. Facebook, Flickr, Twitter, Instagram, Pinerest, YouTube and others allow you to post your astrophotos, including videos, online in accounts you establish. Some people set up their own blogs and web pages to highlight their work. There are even commercial astrophotographers who sell their work via the Internet.

You can share your astrophotos taken with your smartphone or tablet by email, Twitter, Facebook or other social media that your device supports in its operating system. Once you have the astrophoto you can click on the “share” option and go from there. It is a good idea to send yourself a copy to put in your astrophoto files.

For DSLRs once you have downloaded your image to your computer you can send it out via the social media of your choice by uploading it to the platform you desire. Some DSLRs have WiFi capability built in or are capable of being added on so you can use it to your advantage. Don’t do this at sea but rather when you return home to your own network, so as to have higher bandwidth and avoid possible shipboard charges.

Once you think you have a really good or unique astrophotograph taken at sea (or on land if you continue your astrophotography ashore) and it might generate some interest consider submitting it to a news outlet or astronomy-related website. Your local newspapers might like to see your work so consider them, too.

Here are some outlets that you might consider sending your best work to.

Astronomy Picture of the Day (APOD) NASA.gov

MSN.com

Earth and Sky.org

Popular Science.com

Earth Picture of the Day (EPOD).org

The Planetary Society.com

Sky and Telescope .com

Astronomy.com

Space.com

Universe Today.com

Your local TV and newspaper

Each of these entities, as well as those you might want to consider yourself, have either a “Contact Us” or “Submit Your Photo” listed on their webpage that you would use to send your astrophoto to them for consideration. You need a bit of discipline here, supported by your astrophotographer’s eye, to enhance your chances of your image being published online. You do not want to send “run of the mill” astrophotographs that show “just” the Moon, or a planet in the sky. You need to provide something that is unique – and taking astrophotographs at sea is unique.

Planetary alignments, shots of the Moon during eclipse, earthshine, night sky shots in specific places and unusual phenomena seen in the sky – all these are legitimate contenders. Don’t send in every astrophoto you take for consideration, but don’t hold back from doing so if you think it is something that an editor would want to post.

We have come to the point in the book where we have said all that we think needs to be said about astrophotography at sea. Hopefully you feel inspired to start taking your own astrophotographs at sea. Our craft is one in which we learn more with each astrophotograph we take onboard ship.

It can become a lifelong pursuit for you – one that doesn’t have to end when you walk down the gangway and return home. Our next and last chapter tells you how you can become a landlubber astrophotographer.

© Springer Nature Switzerland AG 2018

Gregory I. RedfernCruise Ship Astronomy and AstrophotographyThe Patrick Moore Practical Astronomy Serieshttps://doi.org/10.1007/978-3-030-00958-8_19

19. Bringing the Astrophotography Bug Ashore

Gregory I. Redfern1 

(1)

NASA JPL Solar System Ambassador, Ruckersville, VA, USA

Welcome home! Now that you are ashore does that mean you have to stop taking astrophotographs? Not at all. In fact, if you want to pursue your astrophotography while on land or even other water-based venues such as sailboats, motor boats, lakes, you are in luck. Why? Everything you have applied while at sea to taking astrophotographs will be applicable ashore and on other water locations. And you will find it so much easier to take astrophotographs ashore or on a lake than a ship at sea.

The reason is pretty obvious, as you lose your sea legs and get used to terra-firma again – there is no motion in the ocean to contend with. Even on a lake, unless it is being windswept, you are now photographing the sky from a solid and more tranquil environment. You’ll be amazed at the difference with regard to difficulty – land is so much easier than at sea.

Hopefully this book has you now hooked on astrophotography and you want to learn more about the universe in which you live. If so, welcome to the world of amateur astronomy, a global community of dedicated amateur astronomers and astrophotographers who enjoy looking at the sky, learning about the universe, and photographing it.

If you are interested in getting “deeper” into astronomy and astrophotography you are living in the golden age of being able to do so. The Internet provides an almost unlimited resource on astronomical research, on line astronomy/astrophotography publications, astronomy-related organizations from the private, public, academic, government and vendor realms and much more.

You can use Twitter to keep up on astronomy and space-related news, people and facilities. Researchers, astronauts, observatories, astronomy- related publications, science and government organizations all have Twitter (and Facebook for some) accounts to stay in touch with the public. Now that you don’t have to worry about limited bandwidth and shipboard charges the Internet really needs to become part of your astronomy/astrophotography routine.

Another thing you might want to consider doing is joining a local astronomy club in your area. These clubs are an invaluable resource for you, as you can go to meetings and learn about the sky, telescopes and more. You will meet like-minded people, and most astronomy clubs conduct regular “star parties” in which they go to an observing site to look at the sky – with some photographing it as well – through their telescopes. To see if there is a club in your area check the Astronomical League website. Pull up “Astronomy Clubs” for your state and see if there are any nearby where you live.

If there isn’t an actual club, check to see if you have any science museums or universities/colleges nearby with an astronomy department. These institutions may conduct regular astronomy-related events, including telescope viewing if they have an observatory or telescopes set up for the public.

Your local college or university might also have astronomy classes available for seniors, pass/fail or auditing.

If none of these resources is available, don’t worry, as you can pursue your now land-based astronomy/astrophotography interest quite well on your own. Another huge astronomy education resource is Open Culture, which offers free online astronomy, physics and math courses from some of the best schools and professors in the United States. It is highly recommended that you take advantage of this resource.

If you took pictures at sea you can use the same equipment and setup ashore. If you are happy with what you have, fine. But as your interest expands, so will your requirement for better camera capability. We discussed camera types previously, but if you are getting serious in pursuing astrophotography, perhaps even with a telescope in the future (which we will discuss later in this chapter), you really need to consider getting a DSLR . One good one for astrophotography is the Nikon D810a.

You can research online all of the different DSLRs that are out there and read the various reviews about them. If you find a particular model you are interested in see if your local camera store or mega electronics-consumer warehouse has it available for you to actually see in person. Shop around for best price and be sure to buy a viable warranty, as you will be spending some money for a capable DSLR and boy, accidents can happen. Recommendations on lenses to have can be found in Chap. 14, so you can review that and proceed accordingly as your budget allows.

There are some other astrophotography camera options for you – CCDs and video cameras. This is entering the realm of where you are using devices that are specifically and only for taking astronomical images – they cannot be used for anything else. They are powerful imagers and can run from hundreds to thousands of dollars. Most high-end devices use sensors that are tuned for astronomical use and in some instances can even be mated to a camera lens to take astrophotographs of the night sky, like a DSLR.

It is not recommended taking an astronomically dedicated CCD/video camera with lens attachment capability to sea, as they are expensive, would be really unwieldy and are not efficient at all in a shipboard environment.

These devices for astrophotography come in all shapes and sizes and price tags. They can be color or monochrome imaging units with large or small pixel size, be round, cylindrical or rectangular in their housings, act as camera and/or auto guider (for keeping a telescope locked onto its photo target) in some instances and be geared to deep sky and/or Solar System imaging. Going this route takes a lot of research and introspection on how you want to proceed.

Nothing says – except your budget and the amount of time you have available – that you can’t have separate at sea and ashore astrophotography capabilities. It is up to you to decide. Remember, you can always experiment and upgrade as you go along. The key is to have a core capability in both environments that allows you to take astrophotographs as you progress in equipment and experience acquired.

If you own or buy telephoto lenses you can use them ashore quite easily to take astrophotographs of the Moon, bright stars and the planets. You will be limited in your exposure time only by Earth’s rotation and the resultant image trailing that occurs when your exposure is too long. This won’t be a factor on bright astronomical objects but will be if you try to shoot dim deep sky objects such as star clouds, nebulae and star clusters.

One way to avoid image trailing and take exposures of long length is to invest in a motorized mount for your camera. There are some mounts out there that are not motorized, but these are not recommended as you have to manually move them to keep an astronomical object centered – not a good way to take an astrophotograph.

Motorized mounts use a motor or motors to move the platform your camera is attached to in order to compensate for Earth’s rotation, so that you do not get star trailing. Once again there are many motorized mounts out there for you to choose from, and they can vary from fairly simple to use and light in weight to computer controlled and large in size and weight. Some motorized mounts are used for cameras only, while others can be used for telescopes and/or cameras – more on that later when we discuss telescopes.

There are two basic types of motorized camera and telescope mounts, equatorial or altazimuth. With equatorial mounts they have to be aligned on the north or south celestial pole and have a declination axis (north or south movement) and right ascension axis (east and west movement). Most mounts come with or have as an option a polar alignment scope that helps you center on your respective celestial pole.

Altazimuth mounts do not have to be aligned on the North or South Celestial Pole but still need some type of alignment so that their altitude axis and azimuth axis can follow the stars. Some models of these type mounts are computer controlled as are some equatorial mounts.

Each type of mount will have its pros and cons, which you can determine by reading reviews online. Generally speaking the altazimuth mounts are simpler, lighter and can’t carry as heavy a load as equatorial mounts.

Depending on what type of mount you select you will have to get a suitable tripod to hold the mount and your telescope and camera. Be sure to get a tripod that will safely and effectively handle the maximum weight of your setup. You can have the best camera, optics and mount in the world. But if the tripod that supports it all is too flimsy for the weight load your images will show it or worse yet, you could experience a tripod tipover.

Another consideration for your advancing astrophotography and astronomy interest is buying a telescope. This is a big step for anyone and must be carefully researched. People who are new to telescopes think that “bigger and more powerful” is better, which is true to some extent. But as you increase the size of the telescope you are increasing cost, weight and complexity.

If you are considering buying a telescope you really have to ask yourself these questions:

How much do I want to spend?

There are people who have spent tens of thousands of dollars on a telescope, mount, camera gear, computers and an observatory to house it all. You can go that route if you want, but the good news is that you don’t have to in order to get a really decent and capable telescope.

What do I want to do with a telescope?

Are you interested in visual observation only, or do you want to do astrophotography as well? Most quality telescopes have the capability to accommodate astrophotography of the Moon, planets and deep sky objects using the telescope itself – think super-sized telephoto lens. Most telescopes also allow for mounting a camera piggyback on the telescope tube itself or using the telescope’s mount to attach a camera to it.

Will I want to be mobile or permanent in my telescope setup?

This is where size and type of telescope, your ability to lift and move telescope components – tripod, telescope tube, telescope mount, counterweights, power supply, camera, lenses and necessary accessories – comes into play. To go mobile, even if just setting up outside in your own backyard, requires considerable effort and, on hot days and nights, sweat. Also, can your car and residence hold all of this gear?

How often do you expect to use your telescope?

We all have good intentions, but how often do you really think you will get your telescope out? Do you work? Have a family? Have to go up and down stairs to get to your gear to take outside?

You need to consider all of these aspects to see if it is worth your time, money and effort to get a telescope. If you joined an astronomy club you have the opportunity to try out different types of telescopes if your club hosts star parties or observing sessions. See the Suggested Reading and Internet Sites section for this chapter for help here.

If you do decide to take the plunge BUY QUALITY! A quality telescope, like a quality camera with quality lenses, will last you a lifetime. Telescopes can last decades. It takes planning, time and effort to use your telescope visually and for astrophotography, but we think it is worth it.

With telescopes you can visually observe and photograph the Sun (with proper solar filters that fit over the front of the telescope) in white light and at the wavelength of hydrogen alpha light, the Moon, planets and various deep sky objects. With almost all telescopes you can buy accessories that allow you to do astrophotography using smartphones, tablets, pocket cameras, DSLRs, CCDs, video cameras. It is really amazing the quality of the astrophotographs that can be obtained using smartphones and tablets. The key is the quality of the image being photographed and the steadiness of the device taking it.

Telescopes can allow you to use them as super telephoto lenses by shooting at prime focus, in which your camera – usually a DSLR or an astronomical CCD camera – is physically attached to the telescope. The lens or mirror of your telescope produces an image at a precise focal point at which point eyepieces are used to magnify the image to get greater detail. When shooting at prime focus you are photographing the image formed only by the telescope’s mirror or lens. The prime focus image will be the brightest and largest field of view you can get with your telescope unless you use a focal reducer, which can increase your field of view. Prime focus is normally used for photographing deep sky objects when you are looking for the brightest image and when a large field of view is required, such as looking at the Moon or Sun (with an approved solar filter).

You can also use eyepieces and/or a Barlow lens (used to magnify the image produced at prime focus or in eyepieces) to see and photograph greater detail on the Sun (with an approved and certified solar filter mounted on the front of your telescope), Moon and planets. Smartphones and tablets secured on a holder next to the eyepiece are usually used to take this type of picture – the image formed in an eyepiece that is projected into the camera lens. It can be done with DSLRs, video and CCD cameras as well. This method is called eyepiece projection.

Some telescopes allow a camera – usually a DSLR with a lens – to be attached to the telescope tube itself so that the camera can take lengthy time exposures. The telescope’s mount tracks the stars to counteract Earth’s rotation so you can get some really nice astrophotographs using whatever lens you prefer.

Another option if you cannot attach a camera to your telescope tube is to use the telescope’s mount itself to take longer exposures. Swap out the plate that holds your telescope for one that will hold a camera adapter to securely hold the camera and whatever lens you want to use. This third party accessory is a hefty piece of metal that has a universal socket screw that can hold a DSLR and a heavy telephoto lens. You can move the mount and camera setup anywhere in the sky and not worry about anything falling off (Figs. 19.1 and 19.2).

Fig. 19.1

Object viewed: Andromeda Galaxy. (Image by the author)

Lens used: 250 mm telescope at prime focus

ISO : 5000

Exposure: 30 seconds

Comment: The center region of M-31with some dust and spiral arms is visible in this short time exposure shot

Fig. 19.2

Object viewed: Andromeda Galaxy. (Image by the author)

Lens used: 200–500 mm f/5.6 taken at 850 mm with 1.7x extender

Exposure: 240 seconds

ISO : 3200

Comment: Telephoto image taken from author’s backyard using telescope mount. You can begin to see a bit of trailing in the image

A telescope mount cannot perfectly track the sky due to a variety of reasons – atmospheric conditions, imperfections in alignment and mechanical components of the mount. To compensate for this you can use an autoguider, a small camera that attaches to the telescope or to another telescope mounted to yours that continuously monitors the stars in its field of view and makes automatic corrections to move your mount to keep stars steady in their positions.

The autoguider sends signals via a cable from it to an input jack on your mount that commands the telescope mount to move in RA and declination to keep your image centered with no or very minimal star trailing. This autoguiding feature is found on higher end telescopes and can be very useful.

You can also opt to guide your telescope manually using an illuminated guiding eyepiece. This is an accessory that has red LED illuminating crosshairs in the eyepiece. You center your guide star in the crosshairs and keep it there using your telescope’s controls. This can be attached to a separate guiding telescope mounted and aligned to your primary telescope or it can be used with your telescope in conjunction with an off-axis guider.

Obviously the complexity and gear involved with each of these setup scenarios increases as you acquire more capability.

One other option is renting robotic telescopes online. Yes, you can rent or pay for the use of a telescope online that allows you to observe and photograph astronomical objects from private and commercial observatories around the world. This is a very convenient and relatively inexpensive compromise to having your own telescope. Do an Internet search of “renting robotic telescopes online” and see if this is of interest to you.

Some of the companies that offer this service have impressive equipment and facilities, even research-grade telescopes and astronomical CCD cameras that you can use. Their observatories are in dark sky locations in both the Northern and Southern Hemispheres.

You can chose various telescopes and cameras to take wide-field black and white or color astrophotographs or deep-sky close ups. Some users do research on asteroids and comets. The choice is yours. Some companies have a monthly subscription charge that applies to your rental expenses for the telescopes you use based on an established rate. It really is a nifty way to get your astrophotography fix using top of the line facilities and equipment.

Once you have decided that you want to do astrophotography or astronomy ashore, and made a determination as to what camera and equipment, telescope or not, you want to buy, you will eventually need a location to do what you want. You may prefer to start from your own residence to become familiar with using your ashore setup before venturing to a dark sky site. Almost all of Redfern’s Rules of Astrophotography will apply ashore.

You will be stable being on land and in one spot, so your location will be fixed as you use your astronomical software, planisphere or star charts to guide you in what is visible in the sky. Even in New York City the sky awaits and is visible in all of that light pollution. Many people think that you cannot see the sky in such a venue, but that is wrong, as you can.

You just won’t be looking at the Milky Way Galaxy stretching across the sky anytime soon. But the Moon and the planets are easily visible and photographed. Cityscapes at night with astronomical objects in the same frame can make for some very beautiful photographs. Viewing the Moon and planets in a telescope will be quite the sight to see, with no issues caused by light pollution. They can be photographed from an urban setting, too.

If you have access to a national park, state park or some other natural area near you this is where you want to go to get darker skies to photograph the Milky Way and the night sky. The national parks are having more and more astronomy-related events and dark sky protection and appreciation of them in a big way. To see if there is a national park in your area check out the Appendix of this book.

Many parks and land areas have lakes and rivers that can add an incredible vista to compliment any astrophotographs you take. You may also live near the seashore. Ashore you may prefer to do your water-included astrophotography from the shoreline as opposed to being in a watercraft of some type, as it is much simpler and safer to do. Unless you are very wealthy these vessels will be small with little or no deck space. And it is not an easy environment to take pictures, especially at night.

Boating Safety Notes

DO NOT take pictures if you are the owner/operator, as you are the responsible party for the safety of the vessel or boat and all aboard. Safety of navigation and safety of the vessel or boat and its occupants is your first and only priority. Everyone aboard must be wearing a lifejacket for safety while on the water. Occupants must be sitting down for their safety and that of others, as standing up in a small vessel or boat is dangerous. DO NOT go out on the water by yourself.

Now you can see why it is easier to be on the shoreline. If you are a guest aboard you can try to take pictures, but it will be difficult due to the limited space compared to a cruise ship. You probably could not set up a full-fledged tripod. Also, you would not want to take any expensive camera gear with you to such an environment, as accidents – read gear dropped overboard, gear getting wet from water spray or water in the vessel or boat – will happen. It’s one thing to drop something on land as opposed to doing so on the water. Being on a river would be tough also, as it has its own current that would be hard to compensate for.

Being on a riverbank, lake or sea shoreline really allows you to get creative with your astrophotographs, The water becomes an integral part of your astrophotography, and if you are lucky the water surrounding landforms and sky can blend into one with the reflections of the stars in the water. That is a really cool occurrence, as you can see (Fig. 19.3).

Fig. 19.3

Objects viewed: The stars and mountain reflected in a lake. (Image by the author)

Lens used: 14 mm f/2.8

ISO : 3200

Exposure: 30 seconds

Comment: The stars above Sharp Top Mountain and Lake Abbott at Peaks of Otter, VA

When you do find a site, which can even be at home, that you want to photograph the sky from, just input the location into your astronomical software either by actual name of your city and country or by latitude and longitude if it isn’t listed by name. For your planisphere adjust for your latitude to see what is in the sky, and if you use star charts get the proper ones for the time of the year. Then see what is available in the sky and set up your camera accordingly.

If you are using a telescope that is computer controlled – perhaps by using software on a laptop, iPhone or iPad – go through the telescope set up procedure and then synchronize your software to it. You can also use a WiFi network to control the telescope, using whatever device you choose so there are no wires involved between telescope and controlling device. There will probably be other cables involved with your telescope set up involving power supply, mount input and hand control box, so having one less cable can make a difference. You’d be surprised as to how much cable run you could have.

If you are using a camera and lenses in lieu of taking pictures through a telescope, the camera settings you used at sea for each astronomical object can be changed somewhat, as you are not compensating for motion. Happily this change in environment will allow you to take longer exposures and avoid the “EKG” look to your star images due to motion in the ocean.

What you will have to be mindful of in taking your night sky images which you probably didn’t have to worry about at sea, is light pollution. If you are in an urban or suburban location you will have light glow in the sky. This can be the entire sky or “light cones” situated around your horizon (Fig. 19.4).

Fig. 19.4

Object viewed: Mars and Jupiter. (Image by the author)

Lens: 14 mm f/2.8

Exposure: 30 seconds

ISO : 3200

Comment: Light pollution cones are seen along the horizon at Shenandoah National Park in an otherwise dark sky site

How much light pollution is present will determine how long of an exposure you can take before it overwhelms the image. It can also affect what ISO setting you use. You may have to use a lower ISO to offset the sky glow. SAAS applies here, as you take an exposure and then make adjustments accordingly. You can also offset light pollution somewhat in your astrophotograph processing by using some of the tools such as contrast, white balance, exposure and others. The key is to try and make as dark a sky background as possible.

There are filters you can purchase for your lenses and telescope that can help reduce light pollution. These filters cannot get rid of all of the light pollution, but they can make a difference in the sky background. Telescopes, cameras, eyepieces and CCD cameras have a whole assortment of filters for taking specific wavelengths of light when photographing Solar System and deep sky objects. This is in the realm of very advanced astrophotography,

In Chap. 18 we discussed basic image processing, and now that you are ashore and looking to improve and advance your astrophotography you may want to look at an image processing upgrade. There are a number of freeware and commercial image processing software programs that are in wide use. Some of the commercial applications allow for a trial period in which you can download them and use them for free for a specified period of time. At the end of the trial period you have the option of buying the application and become eligible for upgrades.

These commercial image processing applications can be expensive but are very powerful. Some are astrophotography-centric while others are not. Astrophotographs can be processed using non-astronomical software. You have to be mindful of what computer operating system you use as you evaluate these applications, as some are not viable on a Mac platform and are Windows only. There is a preference for Windows OS in the astronomy/astrophotography world, but Mac users can find suitable applications and hardware out there.

Take your time in evaluating each of these applications before actually purchasing them. Read reviews and the instruction manual – remember Rule 1 – for each. There will be a learning curve associated with these applications, and it will take time to develop familiarity with them. But this can be part of your commitment to astrophotography ashore by upgrading your camera, taking the telescope plunge and using powerful software for image processing.

As we near the end of our journey that we have taken together in these pages here is something more for you to remember. Never let the quest for that perfect picture rob you of seeing and appreciating the sky, whether it be at sea or ashore. Take the time to view the vista before your eyes. The image in our brain formed with our own eyes, and those images imbedded in our memory is far more important than the ones we take with our cameras and telescopes. These images we carry within ourselves for all our lives can nourish our souls whenever necessary or help us to contemplate the universe we live in.

And that, is the greatest gift we can give ourselves as we pursue our passion of collecting photons from the universe from wherever we may be.

Fair winds and following seas, shipmate. May your skies be clear and your seas calm wherever you may sail.

Appendix: Suggested Reading and Internet Sites

PART I Cruise Ship Astronomy

Preface

Springer Astronomy https://​www.​springer.​com/​gp/​astronomy

Chapter 1 Cruise Considerations and What to Pack Astronomy- Wise

Links

PERSONALLY EXPERIENCED CRUISE LINES

Azamara Club Voyages https://​www.​azamaraclubcruis​es.​com

Cunard http://​www.​cunard.​com

Holland America Lines http://​www.​hollandamerica.​com

Oceania Cruises http://​www.​oceaniacruises.​com

Regent Seven Seas https://​www.​rssc.​com

Royal Caribbean International https://​www.​royalcaribbean.​com

Sea Dream Yacht Club  https://​seadream.​com

Windstar Cruises https://​www.​windstarcruises.​com

CRUISE LINE LISTING

https://​en.​wikipedia.​org/​wiki/​List_​of_​cruise_​lines

BINOCULARS AND MONOCULARS

http://​www.​skyandtelescope.​com/​astronomy-equipment/​choosing-astronomy-equipment/​binoculars/​

http://​www.​skyandtelescope.​com/​astronomy-blogs/​ridiculously-small-optics/​

PLANISPHERES

http://​www.​skyandtelescope.​com/​astronomy-resources/​star-finding-with-a-planisphere/​

Safety Of Life At Sea (SOLaS)

http://​www.​imo.​org/​en/​About/​conventions/​listofconvention​s/​pages/​international-convention-for-the-safety-of-life-at-sea-(solas),-1974.​aspx

Chapter 2 Big Bang to Homo Erectus to Multi-Messenger Astronomy

Suggested Reading

Yuval Noah Harari, ”Sapiens - A Brief History of Humankind”

Steven Weinberg. “The First Three Minutes: A Modern View Of The Origin Of The Universe”

Alan Guth, “The Inflationary Universe”

Neil deGrasse Tyson, Michael A. Strauss, J. Richard Gott, “Welcome to the Universe: An Astrophysical Tour”

Links

Aristotle

http://​www.​ucmp.​berkeley.​edu/​history/​aristotle.​html

Aristarchu s

http://​www.​astro.​cornell.​edu/​academics/​courses/​astro201/​aristarchus.​htm

Geocentric Universe

https://​earthobservatory​.​nasa.​gov/​Features/​OrbitsHistory/​

Eratosthenes

http://​www.​astro.​cornell.​edu/​academics/​courses/​astro201/​eratosthenes.​htm

Ptolemy

https://​sunearthday.​nasa.​gov/​2006/​locations/​ptolemy.​php

https://​www.​britannica.​com/​topic/​Almagest

Ptolemaic System

http://​galileo.​rice.​edu/​sci/​theories/​ptolemaic_​system.​html

Nicolaus Copernicus

http://​galileo.​rice.​edu/​sci/​theories/​copernican_​system.​html

Tycho Brahe

http://​galileo.​rice.​edu/​sci/​brahe.​html

Johannes Kepler

http://​galileo.​rice.​edu/​sci/​kepler.​html

Kepler’s Three Laws of Planetary Motion

http://​www.​ifa.​hawaii.​edu/​users/​joseph/​7.​Kepler.​pdf

Platonic Solids

http://​www.​georgehart.​com/​virtual-polyhedra/​kepler.​html

Galileo Galilei

https://​www.​smithsonianmag.​com/​science-nature/​Galileos-Revolutionary-Vision-Helped-Usher-In-Modern-Astronomy-34545274/​

https://​www.​washingtonpost.​com/​wp-srv/​national/​horizon/​sept98/​galileo.​htm

Sidereus Nuncius

https://​library.​si.​edu/​digital-library/​book/​sidereusnuncius0​0gali

Issac Newton

http://​www.​newton.​ac.​uk/​about/​isaac-newton/​life

Philosophiae Naturalis Principia Mathematica

https://​plato.​stanford.​edu/​entries/​newton-principia/​

Gravity

https://​web.​stanford.​edu/​~buzzt/​gravity.​html

Thomas Harriot

http://​galileo.​rice.​edu/​sci/​harriot.​html

Telescopes

http://​galileo.​rice.​edu/​sci/​instruments/​telescope.​html

https://​www.​smithsonianmag.​com/​science-nature/​Galileos-Revolutionary-Vision-Helped-Usher-In-Modern-Astronomy-34545274/​

History of Astrophotography

https://​en.​wikipedia.​org/​wiki/​Astrophotography​

Albert Einstein

https://​www.​nobelprize.​org/​nobel_​prizes/​physics/​laureates/​1921/​einstein-bio.​html

https://​starchild.​gsfc.​nasa.​gov/​docs/​StarChild/​whos_​who_​level2/​einstein.​html

http://​content.​time.​com/​time/​magazine/​article/​0,9171,993017,00.​html

Theory of Special Relativity

https://​www.​space.​com/​36273-theory-special-relativity.​html

E=mc 2

https://​www.​forbes.​com/​sites/​startswithabang/​2018/​01/​23/​the-three-meanings-of-emc2-einsteins-most-famous-equation/​#30651c4571c0

Theory of General Relativity

https://​www.​forbes.​com/​sites/​startswithabang/​2018/​06/​09/​ask-ethan-if-mass-curves-spacetime-how-does-it-un-curve-again/​

Quantum Mechanics

https://​www.​sciencedaily.​com/​terms/​introduction_​to_​quantum_​mechanics.​htm

George Ellery Hale

https://​www.​mtwilson.​edu/​george-ellery-hale/​

http://​nasonline.​org/​publications/​biographical-memoirs/​memoir-pdfs/​hale-george-ellery.​pdf

https://​archive.​nytimes.​com/​www.​nytimes.​com/​learning/​general/​onthisday/​bday/​0629.​html

Mount Wilson Observatory

https://​www.​mtwilson.​edu

Georges Lemaître

https://​www.​amnh.​org/​explore/​resource-collections/​cosmic-horizons/​profile-georges-lemaitre-father-of-the-big-bang/​

http://​www-history.​mcs.​st-andrews.​ac.​uk/​Biographies/​Lemaitre.​html

Edwin Hubble

https://​www.​spacetelescope.​org/​about/​history/​the_​man_​behind_​the_​name/​

Milton Humason

https://​www.​csmonitor.​com/​Science/​Cool-Astronomy/​2010/​0519/​How-a-janitor-at-the-Mount-Wilson-Observatory-measured-the-size-of-the-universe

Expansion of the Universe

http://​skyserver.​sdss.​org/​dr1/​en/​astro/​universe/​universe.​asp

http://​curious.​astro.​cornell.​edu/​about-us/​104-the-universe/​cosmology-and-the-big-bang/​expansion-of-the-universe/​623-what-is-the-universe-expanding-into-intermediate

Fritz Zwicky

https://​www.​sps.​ch/​en/​articles/​history-of-physics/​fritz-zwicky-an-extraordinary-astrophysicist-6/​

Hans Bethe

https://​www.​nobelprize.​org/​nobel_​prizes/​physics/​laureates/​1967/​bethe-bio.​html

https://​physics.​aps.​org/​story/​v21/​st3

Vera Rubin

https://​www.​aip.​org/​history-programs/​niels-bohr-library/​oral-histories/​33963

https://​www.​nature.​com/​articles/​542032a

Kent Ford

https://​www.​britannica.​com/​biography/​W-Kent-Ford

Dark Matter

https://​cosine.​yale.​edu/​about-us/​what-dark-matter

Big Bang

https://​www.​cfa.​harvard.​edu/​~ejchaisson/​cosmic_​evolution/​docs/​splash.​html

https://​science.​nasa.​gov/​astrophysics/​focus-areas/​what-powered-the-big-bang

Arno Penzias and Robert Wilson

https://​www.​aps.​org/​programs/​outreach/​history/​historicsites/​penziaswilson.​cfm

https://​www.​nobelprize.​org/​nobel_​prizes/​physics/​laureates/​1978/​

Robert Dicke

https://​www.​google.​com/​url?​sa=​t&​rct=​j&​q=​&​esrc=​s&​source=​web&​cd=​11&​cad=​rja&​uact=​8&​ved=​0ahUKEwinzpvftqv​cAhUlhOAKHQLuDwk​QFghsMAo&​url=​https%3A%2F%2Ftwitter.​com%2Fbgreene%2Fstatus%2F97051134683092​5824&​usg=​AOvVaw2HJxu8r5JN​0w4k15buyRJY

https://​phy.​princeton.​edu/​department/​history/​faculty-history/​robert-dicke

P.J.E. Peebles

https://​phy.​princeton.​edu/​people/​p-james-peebles

Cosmic Microwave Background (CMB)

https://​www.​scientificameric​an.​com/​article/​what-is-the-cosmic-microw/​

COBE Mission

https://​science.​nasa.​gov/​missions/​cobe

John Mather

https://​www.​nobelprize.​org/​nobel_​prizes/​physics/​laureates/​2006/​mather-facts.​html

George Smoot

https://​www.​nobelprize.​org/​nobel_​prizes/​physics/​laureates/​2006/​smoot-bio.​html

http://​www2.​lbl.​gov/​Publications/​Nobel/​

WMAP Mission

https://​map.​gsfc.​nasa.​gov

https://​www.​nasa.​gov/​topics/​universe/​features/​wmap-complete.​html

http://​www.​skyandtelescope.​com/​astronomy-news/​wmap-refines-precision-cosmology/​

Planck Mission

http://​www.​esa.​int/​Our_​Activities/​Space_​Science/​Planck

http://​planck.​cf.​ac.​uk/​science/​cmb

Dark Energy

https://​science.​nasa.​gov/​astrophysics/​focus-areas/​what-is-dark-energy

https://​www.​scientificameric​an.​com/​article/​blinded-by-the-dark-energy/​

https://​www.​nobelprize.​org/​nobel_​prizes/​physics/​laureates/​2011/​press.​html

Hubble Constant

https://​www.​cfa.​harvard.​edu/​~dfabricant/​huchra/​hubble/​

https://​wmap.​gsfc.​nasa.​gov/​universe/​uni_​expansion.​html

Hubble Space Telescope

http://​www.​stsci.​edu/​hst/​HST_​overview

Cosmological Parameters

https://​wmap.​gsfc.​nasa.​gov/​mission/​sgoals_​parameters.​html

Inflation Theory

https://​wmap.​gsfc.​nasa.​gov/​universe/​bb_​cosmo_​infl.​html

https://​www.​edge.​org/​conversation/​alan_​guth-the-inflationary-universe

String Theory

https://​www.​smithsonianmag.​com/​science-nature/​string-theory-about-unravel-180953637/​

https://​www.​scientificameric​an.​com/​article/​is-string-theory-science/​

https://​www.​forbes.​com/​sites/​startswithabang/​2016/​11/​25/​what-every-layperson-should-know-about-string-theory/​#3250f2b15a53

Multiverse

https://​www.​scientificameric​an.​com/​article/​multiverse-the-case-for-parallel-universe/​

https://​www.​smithsonianmag.​com/​science-nature/​can-physicists-ever-prove-multiverse-real-180958813/​

Gravitational Waves

https://​www.​ligo.​caltech.​edu/​page/​what-are-gw

https://​vimeo.​com/​252816795

https://​www.​ligo.​org

https://​wtop.​com/​the-space-place/​2018/​06/​gravitational-waves-ripple-dc-audience/​slide/​1/​

https://​www.​ligo.​org/​science/​GW-Stochastic.​php

Multi-Messenger Astronomy

https://​www.​spacetelescope.​org/​science/​gravitational_​waves/​

https://​wtop.​com/​the-space-place/​2017/​10/​wondrous-discovery-kilonova-may-explain-gold-platinum-uranium-created/​

Homo Erectus

http://​humanorigins.​si.​edu/​evidence/​human-fossils/​species/​homo-erectus

https://​www.​nature.​com/​scitable/​knowledge/​library/​homo-erectus-a-bigger-smarter-97879043

Homo Sapiens

http://​humanorigins.​si.​edu/​evidence/​human-fossils/​species/​homo-sapiens

NIKON SCALE OF THE UNIVERSE

https://​www.​nikon.​com/​about/​sp/​universcale/​

Chapter 3 Using Your Ship-Observatory at Sea

Links

http://​earthsky.​org/​astronomy-essentials/​universal-time

https://​www.​nhc.​noaa.​gov/​aboututc.​shtml

https://​support.​garmin.​com/​en-US/​?​faq=​lQFTLBSlv73TYGsO​pDB7P6&​searchType=​noProduct&​utm_​source=​faqSearch

http://​www.​slate.​com/​blogs/​bad_​astronomy/​2009/​01/​15/​how_​far_​away_​is_​the_​horizon.​html

Chapter 4  Location, Location, Location

Links

https://​www.​rmg.​co.​uk/​discover/​explore/​prime-meridian-greenwich

https://​www.​rmg.​co.​uk/​see-do/​we-recommend/​attractions/​stand-worlds-historic-prime-meridian

http://​astronomy.​swin.​edu.​au/​cosmos/​L/​Local+Noon

https://​www.​space.​com/​10821-night-sky-changing-seasons.​html

http://​earthsky.​org/​tonight/​moon-near-celestial-equator-april-26?​utm_​source=​EarthSky+News&​utm_​campaign=​bd3dc53a45-EMAIL_​CAMPAIGN_​2018_​02_​02&​utm_​medium=​email&​utm_​term=​0_​c643945d79-bd3dc53a45-394691157

https://​spaceplace.​nasa.​gov/​seasons/​en/​

http://​astronomy.​swin.​edu.​au/​cosmos/​S/​Seasons

http://​stars.​astro.​illinois.​edu/​celsph.​html

http://​www.​physics.​csbsju.​edu/​astro/​CS/​CS.​16.​html

Chapter 5 The Sun, Sunsets, Sunrises and More

Suggested Reading

How to Observe the Sun Safely

Authors: Macdonald, Lee

Links

*SOLAR VIEWING AND PHOTOGRAPHING SAFETY*

For your safety each of these links must be read and understood before viewing/photographing the Sun. If you do not understand them contact the appropriate organization. Print them out for reference in case you can not access the Internet at sea.

https://​eclipse.​aas.​org/​eye-safety

https://​www.​skyandtelescope.​com/​astronomy-news/​observing-news/​how-to-look-at-the-sun/​

http://​www.​fpsci.​com/​how_​to_​view.​html

https://​www.​astrosociety.​org/​wp-content/​uploads/​2017/​04/​Fienberg2.​pdf

https://​eclipse.​aas.​org/​eye-safety/​eyewear-viewers

PINHOLE PROJECTION

https://​eclipse.​aas.​org/​eye-safety/​projection

CERTIFIED SOLAR GLASSES AND SOLAR FILTERS

https://​eclipse.​aas.​org/​resources/​solar-filters

https://​eclipse.​aas.​org/​eye-safety/​optics-filters

https://​eclipse.​aas.​org/​resources/​telescopes-binoculars

HOW TO PHOTOGRAPH THE SUN

https://​www.​bhphotovideo.​com/​explora/​photography/​tips-and-solutions/​how-photograph-sun

HOW TO SHOOT SOLAR-ECLIPSE IMAGES & VIDEOS

NOTE: USE THE ADVICE FOR PARTIAL ECLIPSE PHASES

https://​eclipse.​aas.​org/​imaging-video/​images-videos

Be Sure to Read all of the “More Articles About Solar-Eclipse Imaging & Video”

SMARTPHONE

NOTE: USE THE ADVICE FOR PARTIAL ECLIPSE PHASES

https://​eclipse.​aas.​org/​imaging-video/​images-videos

https://​eclipse2017.​nasa.​gov/​smartphone-photography-eclipse

https://​eclipse2017.​nasa.​gov/​can-i-photograph-eclipse-my-smartphone

https://​eclipse2017.​nasa.​gov/​sites/​default/​files/​Photographing%20​the%20​Eclipse%20​with%20​your%20​Smartphone.​pdf

NASA Sun

https://​www.​nasa.​gov/​sun

Solar Transits

https://​www.​nasa.​gov/​kepler/​education/​sstransits

https://​eclipse.​gsfc.​nasa.​gov/​transit/​transit.​html

https://​www.​skyandtelescope.​com/​astronomy-news/​observing-news/​photographing-the-transit-of-venus/​

Sunrise/Sunsets

https://​www.​nikonusa.​com/​en/​learn-and-explore/​a/​tips-and-techniques/​best-tips-for-sunrise-and-sunset-photos.​html

Green Flash

For your safety each of these links must be read and understood before viewing/photographing the Green Flash. If you do not understand them contact the appropriate organization. Print them out for reference in case you can not access the Internet at sea.

SAFETY

https://​www.​atoptics.​co.​uk/​atoptics/​gf1.​htm

https://​www.​skyandtelescope.​com/​observing/​quest-for-the-green-flash/​

http://​earthsky.​org/​tonight/​see-the-legendary-green-flash

Chapter 6 The Stars

Links

Stellar Formation

https://​www.​nasa.​gov/​feature/​goddard/​2017/​messier-42-the-orion-nebula

http://​earthsky.​org/​clusters-nebulae-galaxies/​orion-nebula-jewel-in-orions-sword

https://​science.​nasa.​gov/​astrophysics/​focus-areas/​how-do-stars-form-and-evolve

https://​www.​spacetelescope.​org/​science/​formation_​of_​stars/​

https://​www.​cfa.​harvard.​edu/​COMPLETE/​learn/​protostars/​protostar.​html

https://​imagine.​gsfc.​nasa.​gov/​science/​objects/​stars1.​html

Stellar Nucleosynthesis

https://​helios.​gsfc.​nasa.​gov/​nucleo.​html

Evolution of the Sun

http://​www.​astro.​cornell.​edu/​academics/​courses/​astro201/​evol_​sun.​htm

White Dwarf

https://​imagine.​gsfc.​nasa.​gov/​science/​objects/​dwarfs2.​html

Novae

https://​svs.​gsfc.​nasa.​gov/​11641

http://​www.​astro.​cornell.​edu/​academics/​courses/​astro201/​novae.​htm

Supernovae

https://​imagine.​gsfc.​nasa.​gov/​educators/​lessons/​xray_​spectra/​background-lifecycles.​html

https://​imagine.​gsfc.​nasa.​gov/​science/​objects/​supernovae1.​html

https://​imagine.​gsfc.​nasa.​gov/​science/​objects/​supernovae2.​html

http://​astronomy.​swin.​edu.​au/​cosmos/​C/​Chandrasekhar+Li​mit

http://​astronomy.​swin.​edu.​au/​cosmos/​C/​Core-collapse

http://​www.​astro.​cornell.​edu/​academics/​courses/​astro201/​highmass.​htm

http://​www.​astro.​cornell.​edu/​academics/​courses/​astro201/​sn.​htm

Neutron Stars

https://​imagine.​gsfc.​nasa.​gov/​science/​objects/​neutron_​stars1.​html

Pulsars and Magnetars

https://​science.​nasa.​gov/​science-news/​news-articles/​two-sides-of-the-same-star

Kilonova

https://​wtop.​com/​the-space-place/​2017/​10/​wondrous-discovery-kilonova-may-explain-gold-platinum-uranium-created/​

http://​hubblesite.​org/​news_​release/​news/​2017-41

Black Holes

https://​www.​nasa.​gov/​black-holes

https://​science.​nasa.​gov/​astrophysics/​focus-areas/​black-holes

https://​www.​nasa.​gov/​vision/​universe/​starsgalaxies/​black_​hole_​description.​html

https://​plato.​stanford.​edu/​entries/​spacetime-singularities/​

https://​www.​nasa.​gov/​mission_​pages/​chandra/​multimedia/​cygnusx1.​html

https://​eventhorizontele​scope.​org

Stellar Magnitude

http://​earthsky.​org/​astronomy-essentials/​what-is-stellar-magnitude

http://​www.​skyandtelescope.​com/​astronomy-resources/​the-stellar-magnitude-system/​

http://​www.​skyandtelescope.​com/​astronomy-resources/​how-many-stars-night-sky-09172014/​

Star Colors

https://​www.​universetoday.​com/​24640/​color-of-stars/​

http://​www.​atnf.​csiro.​au/​outreach/​education/​senior/​astrophysics/​photometry_​colour.​html

Constellations

https://​www.​iau.​org/​public/​themes/​constellations/​

Chapter 7 The Milky Way and Other Galaxies

Links

https://​www.​skyandtelescope.​com/​astronomy-news/​milky-way/​

https://​www.​nasa.​gov/​jpl/​charting-the-milky-way-from-the-inside-out

https://​news.​nationalgeograph​ic.​com/​2018/​01/​milky-way-galaxy-facts-black-hole-stars-space-science/​

https://​www.​scientificameric​an.​com/​article/​a-spectacular-spiral-may-encircle-the-milky-way/​

http://​www.​galacticcenter.​astro.​ucla.​edu

http://​earthsky.​org/​favorite-star-patterns/​teapot-of-sagittarius-points-to-galactic-center

https://​www.​skyandtelescope.​com/​observing/​a-trip-down-the-great-rift/​

Gaia

http://​www.​esa.​int/​Our_​Activities/​Space_​Science/​Gaia/​Gaia_​creates_​richest_​star_​map_​of_​our_​Galaxy_​and_​beyond

https://​www.​quantamagazine.​org/​what-astronomers-are-learning-from-gaias-new-milky-way-map-20180508/​

Milkomeda – Milkdromeda

https://​svs.​gsfc.​nasa.​gov/​30955

https://​www.​cfa.​harvard.​edu/​news/​su200822

Supermassive Black Holes

http://​www.​skyandtelescope.​com/​astronomy-news/​do-big-black-holes-wander-the-galaxy/​?​k=​X2eLNeXTAu0pdXJ%2B6SJFkgjffbPJdB​b2myBdgtfo4Cg%3D&​utm_​medium=​email&​utm_​source=​newsletter&​utm_​campaign=​sky-jma-nl-180504

Sgr A*

http://​chandra.​si.​edu/​photo/​2018/​sgra_​swarm/​

LMC/SMC

https://​aasnova.​org/​2018/​05/​18/​history-of-the-magellanic-clouds/​

http://​iopscience.​iop.​org/​article/​10.​3847/​2041-8213/​aac175/​meta

https://​www.​stuff.​co.​nz/​science/​95136379/​roger-hanson-the-little-galaxies-on-our-doorstep

The Local Group

https://​imagine.​gsfc.​nasa.​gov/​features/​cosmic/​local_​group_​info.​html

http://​astronomy.​swin.​edu.​au/​cosmos/​L/​Local+Group

http://​www.​atlasoftheuniver​se.​com

Virgo Cluster

http://​astronomy.​swin.​edu.​au/​cosmos/​V/​Virgo+Cluster

Galactic Superclusters

https://​imagine.​gsfc.​nasa.​gov/​features/​cosmic/​nearest_​superclusters_​info.​html

Laniakea Supercluster

https://​www.​nature.​com/​news/​earth-s-new-address-solar-system-milky-way-laniakea-1.​15819

The Great Attractor

https://​www.​space.​com/​33579-will-the-great-attractor-destroy-us.​html

Cosmic Web

https://​blogs.​scientificameric​an.​com/​sa-visual/​the-beautiful-complexity-of-the-cosmic-web/​

https://​arxiv.​org/​abs/​1705.​03021

Observable Universe

https://​apod.​nasa.​gov/​apod/​ap180508.​html

https://​www.​nasa.​gov/​feature/​goddard/​2016/​hubble-reveals-observable-universe-contains-10-times-more-galaxies-than-previously-thought

Hubble Classification of Galaxies

http://​astronomy.​swin.​edu.​au/​cosmos/​H/​Hubble+Classific​ation

https://​www.​spacetelescope.​org/​images/​heic9902o/​

http://​cas.​sdss.​org/​dr6/​en/​proj/​basic/​galaxies/​ellipticals.​asp

Chapter 8 The Planets

Suggested Reading

Chasing New Horizons: INSIDE THE EPIC FIRST MISSION TO PLUTO by Alan Stern and David Grinspoon

Links

Exoplanets

https://​exoplanets.​nasa.​gov

Proxima Centauri

https://​www.​space.​com/​39829-nearest-exoplanet-proxima-b-superflare.​html

Formation Of The Solar System

https://​www.​youtube.​com/​watch?​v=​x1QTc5YeO6w

https://​youtu.​be/​ukiJWnOv6Eg

https://​www.​space.​com/​35526-solar-system-formation.​html

https://​www.​quantamagazine.​org/​stellar-disks-reveal-how-planets-get-made-20180521/​

Mercury

http://​nineplanets.​org/​mercury.​html

NASA MESSENGER

https://​www.​nasa.​gov/​mission_​pages/​messenger/​main/​index.​html

ESA BepiColombo

http://​sci.​esa.​int/​bepicolombo/​

Venus

http://​nineplanets.​org/​venus.​html

Mars

http://​nineplanets.​org/​mars.​html

Jupiter

http://​nineplanets.​org/​jupiter.​html

https://​cosmosmagazine.​com/​space/​juno-s-new-jupiter

Saturn

http://​nineplanets.​org/​saturn.​html

Uranus

http://​nineplanets.​org/​uranus.​html

Neptune

http://​nineplanets.​org/​neptune.​html

Pluto

http://​nineplanets.​org/​pluto.​html

Chapter 9 The Moon

Suggested Reading

http://​www.​astronomy.​com/​rapid/​2014/​01/​your-guide-to-the-moon

Links

Formation

https://​www.​skyandtelescope.​com/​astronomy-news/​when-and-how-did-the-moon-form/​

http://​newsroom.​ucla.​edu/​releases/​moon-was-produced-by-a-head-on-collision-between-earth-and-a-forming-planet

https://​www.​ucdavis.​edu/​news/​how-moon-formed-inside-vaporized-earth-synestia/​

https://​www.​quora.​com/​If-we-had-a-time-machine-what-would-the-moon-look-like-from-Earth-4-billion-years-ago-How-close-How-big-in-the-sky-would-it-look/​answer/​Corey-S-Powell

Late Heavy Bombardment

https://​www.​nature.​com/​articles/​ngeo1885.​pdf

South Pole-Aitken Basin

https://​moon.​nasa.​gov/​resources/​38/​south-pole-aitken-basin/​

https://​www.​nasa.​gov/​mission_​pages/​LRO/​multimedia/​lroimages/​lola-20100409-aitken.​html

Clementine

https://​nssdc.​gsfc.​nasa.​gov/​planetary/​clementine.​html

https://​www.​airspacemag.​com/​daily-planet/​clementine-legacy-twenty-years-180949523/​

Lunar Prospector

https://​www.​lpi.​usra.​edu/​lunar/​missions/​prospector/​

https://​nssdc.​gsfc.​nasa.​gov/​planetary/​lunarprosp.​html

LCROSS

https://​www.​nasa.​gov/​mission_​pages/​LCROSS/​main/​

http://​science.​sciencemag.​org/​content/​330/​6003/​463

LRO

https://​lunar.​gsfc.​nasa.​gov

Lunar Water

https://​www.​nasa.​gov/​feature/​goddard/​2018/​on-second-thought-the-moons-water-may-be-widespread-and-immobile

http://​earthsky.​org/​science-wire/​scientists-detect-magmatic-water-on-moons-surface

https://​news.​nationalgeograph​ic.​com/​2017/​07/​water-moon-formed-volcanoes-glass-space-science/​

LADEE

https://​www.​nasa.​gov/​mission_​pages/​ladee/​main/​index.​html

GRAIL

https://​www.​nasa.​gov/​mission_​pages/​grail/​main/​index.​html

NASA Moon Plans

https://​www.​nasa.​gov/​feature/​nasa-expands-plans-for-moon-exploration-more-missions-more-science

https://​www.​nasa.​gov/​feature/​nasa-commercial-partners-key-to-sustainable-moon-presence

NASA Lunar Orbital Platform Gateway

https://​www.​nasa.​gov/​feature/​nasa-s-lunar-outpost-will-extend-human-presence-in-deep-space

Earthshine

https://​science.​nasa.​gov/​science-news/​science-at-nasa/​2005/​04oct_​leonardo

Chapter 10 Eclipses

Suggested Reading

Sky & Telescope’s Free Eclipse Photography eBook

https://​www.​skyandtelescope.​com/​eclipse-photography-free-ebook/​ Links

Links

*SOLAR ECLIPSE SAFETY*

For your safety each of these links must be read and understood before viewing/photographing Solar Eclipses. If you do not understand them contact the appropriate organization. Print them out for reference in case you cannot access the Internet at sea.

https://​eclipse.​aas.​org/​eye-safety

https://​eclipse2017.​nasa.​gov/​safety

https://​eclipse.​aas.​org/​eye-safety/​eyewear-viewers

https://​www.​astrosociety.​org/​wp-content/​uploads/​2017/​04/​Fienberg2.​pdf

PINHOLE PROJECTION

https://​eclipse.​aas.​org/​eye-safety/​projection

CERTIFIED SOLAR GLASSES AND SOLAR FILTERS

https://​eclipse.​aas.​org/​resources/​solar-filters

https://​eclipse.​aas.​org/​eye-safety/​optics-filters

https://​eclipse.​aas.​org/​resources/​telescopes-binoculars

HOW TO SHOOT SOLAR-ECLIPSE IMAGES & VIDEOS

https://​eclipse.​aas.​org/​imaging-video/​images-videos

Be Sure to Read all of the “More Articles About Solar-Eclipse Imaging & Video”

SMARTPHONE

https://​eclipse.​aas.​org/​imaging-video/​images-videos

https://​eclipse2017.​nasa.​gov/​smartphone-photography-eclipse

https://​eclipse2017.​nasa.​gov/​can-i-photograph-eclipse-my-smartphone

https://​eclipse2017.​nasa.​gov/​sites/​default/​files/​Photographing%20​the%20​Eclipse%20​with%20​your%20​Smartphone.​pdf

SOLAR ECLIPSES

https://​eclipse.​gsfc.​nasa.​gov/​solar.​html

VERY COMPREHENSIVE

http://​www.​mreclipse.​com/​main/​preview.​html

http://​www.​mreclipse.​com

https://​www.​nasa.​gov/​audience/​forstudents/​k-4/​stories/​annular-eclipse

https://​solarscience.​msfc.​nasa.​gov/​chromos.​shtml

https://​solarscience.​msfc.​nasa.​gov/​surface.​shtml

https://​www.​nasa.​gov/​content/​goddard/​what-is-a-solar-prominence

LUNAR ECLIPSES

https://​eclipse.​gsfc.​nasa.​gov/​lunar.​html

https://​spaceweatherarch​ive.​com/​2018/​05/​24/​lunar-eclipses-and-climate-change/​

Chapter 11 Spotting the International Space Station and Other Satellites

Links

ISS

https://​www.​nasa.​gov/​mission_​pages/​station/​overview/​index.​html

https://​spotthestation.​nasa.​gov

https://​www.​heavens-above.​com

http://​www.​skyandtelescope.​com/​observing/​all-night-vigil-with-the-international-space-station/​?​k=​X2eLNeXTAu0pdXJ%2B6SJFkgjffbPJdB​b2myBdgtfo4Cg%3D&​utm_​medium=​email&​utm_​source=​newsletter&​utm_​campaign=​sky-jma-nl-180525

http://​www.​skyandtelescope.​com/​observing/​satellites/​

http://​www.​skyandtelescope.​com/​observing/​celestial-objects-to-watch/​observing-iridium-flares/​

Chapter 12 Asteroids and Comets, Meteor Showers, Fireballs and Bolides

Links

https://​solarsystem.​nasa.​gov/​small-bodies/​asteroids/​overview/​?​page=​0&​per_​page=​40&​order=​name+asc&​search=​&​condition_​1=​101%3Aparent_​id&​condition_​2=​asteroid%3Abody_​type%3Ailike

https://​www.​nasa.​gov/​content/​hubble-highlights-tracking-evolution-in-the-asteroid-belt

https://​solarsystem.​nasa.​gov/​small-bodies/​comets/​overview/​?​page=​0&​per_​page=​40&​order=​name+asc&​search=​&​condition_​1=​102%3Aparent_​id&​condition_​2=​comet%3Abody_​type%3Ailike

http://​hubblesite.​org/​reference_​desk/​faq/​answer.​php.​id=​19&​cat=​solarsystem

http://​pluto.​jhuapl.​edu/​Participate/​learn/​What-We-Know.​php?​link=​The-Kuiper-Belt

https://​www.​nasa.​gov/​feature/​new-horizons-chooses-nickname-for-ultimate-flyby-target

https://​solarsystem.​nasa.​gov/​solar-system/​oort-cloud/​overview/​

https://​www.​jpl.​nasa.​gov/​edu/​pdfs/​ss_​kuiperbelt.​pdf

https://​www.​nasa.​gov/​planetarydefense​/​overview

https://​spacewatch.​lpl.​arizona.​edu

https://​www.​lpi.​usra.​edu/​meteor/​

https://​asteroidday.​org

https://​www.​lpi.​usra.​edu/​science/​kring/​Chicxulub/​

https://​www.​amsmeteors.​org/​home.​html

https://​eol.​jsc.​nasa.​gov/​esrs/​ISS_​Remote_​Sensing_​Systems/​Meteor.​htm

http://​www.​skyandtelescope.​com/​astronomy-news/​new-study-hunts-for-rain-gutter-micrometeorites/​

https://​www.​amsmeteors.​org/​meteor-showers/​how-to-photograph-meteors-with-a-dslr/​

Chapter 13 Auroras and Other Glows in the Sea and Sky

Links

Aurora

https://​www.​nasa.​gov/​content/​about-auroras

https://​www.​nasa.​gov/​mission_​pages/​sunearth/​aurora-news-stories/​index.​html

https://​solarsystem.​nasa.​gov/​news/​355/​the-aurora-named-steve/​ https://​www.​swpc.​noaa.​gov

https://​www.​swpc.​noaa.​gov/​products/​aurora-30-minute-forecast

Airglow

https://​www.​atoptics.​co.​uk/​highsky/​airglow1.​htm

https://​www.​universetoday.​com/​112237/​how-to-see-airglow-the-green-sheen-of-night/​

Noctilucent Clouds

https://​www.​atoptics.​co.​uk/​highsky/​nlc1.​htm

http://​earthsky.​org/​earth/​night-shining-clouds-noctilucent-clouds-how-they-form-how-to-see-them

https://​www.​nasa.​gov/​mission_​pages/​aim/​index.​html

Zodiacal Light

http://​earthsky.​org/​astronomy-essentials/​everything-you-need-to-know-zodiacal-light-or-false-dusk

http://​earthsky.​org/​space/​what-is-the-ecliptic

https://​www.​atoptics.​co.​uk/​highsky/​zod1.​htm

Zodiacal Band

https://​www.​atoptics.​co.​uk/​highsky/​zodim3.​htm

Gegenschein

https://​www.​atoptics.​co.​uk/​highsky/​zodim3.​htm

http://​www.​skyandtelescope.​com/​observing/​take-the-gegenschein-challenge1014201​51410/​

Solar and Lunar Halos/Dogs/Corona

SOLAR PHENOMENA SAFETY 

For your safety the first two links must be read and understood before viewing/photographing these phenomena. If you do not understand them contact the appropriate organization. Print them out for reference in case you can not access the Internet at sea.

https://​www.​atoptics.​co.​uk/​halo/​photo.​htm

https://​www.​atoptics.​co.​uk/​halo/​p1.​htm

https://​www.​atoptics.​co.​uk/​halo/​contents.​htm

https://​www.​atoptics.​co.​uk/​halo/​dogfm.​htm

http://​www.​skyandtelescope.​com/​astronomy-resources/​astronomy-questions-answers/​why-are-sundogs-called-by-that-name/​

https://​www.​atoptics.​co.​uk/​halo/​parhelia.​htm

http://​earthsky.​org/​space/​what-makes-a-halo-around-the-moon

https://​www.​washingtonpost.​com/​news/​capital-weather-gang/​wp/​2017/​06/​07/​a-virginia-photographer-got-this-lunar-halo-shot-turns-out-it-was-pretty-rare/​?​utm_​term=​.​45f931fe34ac

Rainbows

https://​www.​atoptics.​co.​uk/​bows.​htm

Sea Spray Bows

https://​www.​atoptics.​co.​uk/​rainbows/​seabow.​htm

Lightning

LIGHTNING SAFETY

For your safety each of these links must be read and understood before viewing/photographing Lightning. If you do not understand them contact the appropriate organization. Print them out for reference in case you can not access the Internet at sea.

http://​www.​nws.​noaa.​gov/​om/​marine/​factlightning.​pdf

https://​www.​weather.​gov/​safety/​lightning

https://​www.​nssl.​noaa.​gov/​education/​svrwx101/​lightning/​

https://​www.​nssl.​noaa.​gov/​education/​svrwx101/​lightning/​types/​

Bioluminescence

https://​ocean.​si.​edu/​ocean-life/​fish/​bioluminescence

https://​news.​nationalgeograph​ic.​com/​news/​2012/​03/​pictures/​120319-glowing-waves-ocean-blue-bioluminescent-plankton-science/​

PART II Astrophotography at Sea

Chapter 14 Yes, It Can Be Done and How to Do It

Suggested Reading

https://​www.​skyandtelescope.​com/​astrophotography​-guide-free-ebook/​

Links

Astrophotography

http://​imaging.​nikon.​com/​lineup/​microsite/​astrophotography​/​getstarted/​beginer/​index.​html

Film Cameras

http://​time.​com/​4649032/​film-photography-cameras/​

Smart Phones and Tablets

http://​www.​nightcapcamera.​com/​nightcap-camera/​

https://​itunes.​apple.​com/​us/​app/​nightcap-camera/​id754105884?​mt=​8

https://​www.​camerafv5.​com

https://​opencamera.​sourceforge.​io

Compact Cameras

https://​www.​pcmag.​com/​article2/​0,2817,2401971,00.​asp

https://​astrobob.​areavoices.​com/​2010/​03/​22/​try-astrophotography​-point-and-shoot-style/​

DSLRs

https://​skiesandscopes.​com/​best-camera-for-astrophotography​/​

https://​www.​skyandtelescope.​com/​astronomy-resources/​astrophotography​-tips/​shooting-with-modified-dslr-cameras/​

Chapter 15 Redfern’s Rules of Astrophotography at Sea

Links

ISO

https://​www.​digitaltrends.​com/​photography/​what-is-iso-camera-settings-explained/​

https://​www.​skyandtelescope.​com/​astronomy-blogs/​imaging-foundations-richard-wright/​astrophotography​-understanding-iso/​?​k=​X2eLNeXTAu0pdXJ%2B6SJFkgjffbPJdB​b2myBdgtfo4Cg%3D&​utm_​medium=​email&​utm_​source=​newsletter&​utm_​campaign=​sky-jma-nl-180720&​cid=​DM58234&​bid=​591951446

Lenses

http://​imaging.​nikon.​com/​lineup/​microsite/​astrophotography​/​getstarted/​lens/​index.​html

Cleaning Lenses

https://​photographylife.​com/​how-to-clean-slr-camera-lenses

Chapter 16 Preparing for Your At-Sea Astrophotography Session

Links

Tripods

https://​photographylife.​com/​how-to-use-a-tripod

https://​digital-photography-school.​com/​how-to-use-your-tripod-its-not-as-simple-as-you-think/​

Chapter 17 Taking What the Sea, Sky and Ship Will Give You

Links

https://​oceanservice.​noaa.​gov/​facts/​why_​oceans.​html

http://​www.​sciencemag.​org/​news/​2010/​11/​earth-oceans-were-homegrown

https://​www.​smithsonianmag.​com/​science-nature/​how-did-water-come-to-earth-72037248/​

https://​news.​nationalgeograph​ic.​com/​news/​2014/​10/​141030-starstruck-earth-water-origin-vesta-science/​

https://​www.​nasa.​gov/​specials/​ocean-worlds/​

https://​youtu.​be/​NpuuGpUFJGA

Chapter 18 Process, Print and Post

Suggested Reading

Practical Astrophotography​

Author: Charles, Jeffrey R.

Links

https://​www.​skyandtelescope.​com/​astronomy-resources/​astrophotography​-tips/​deep-sky-with-your-dslr/​

http://​www.​astropix.​com/​html/​j_​digit/​digtechs.​html

Chapter 19 Bringing the Astrophotography Bug Ashore

Suggested Reading

https://​www.​skyandtelescope.​com/​astrophotography​-guide-free-ebook/​

https://​www.​uscgboating.​org/​images/​420.​PDF

Links

https://​www.​astroleague.​org

http://​www.​openculture.​com/​astronomy-free-online-courses

http://​geartacular.​com/​how-to-guide-astrophotography​-with-dslr/​

https://​improvephotograp​hy.​com/​50390/​using-tracking-mount-landscape-astrophotography​/​

https://​www.​skyandtelescope.​com/​astronomy-equipment/​how-to-choose-a-telescope/​

https://​www.​skyandtelescope.​com/​astronomy-resources/​astrophotography​-tips/​

https://​www.​skyandtelescope.​com/​astronomy-resources/​guiding-a-telescope-for-imaging/​

https://​www.​nps.​gov/​findapark/​index.​htm

https://​www.​skyandtelescope.​com/​astronomy-resources/​astrophotography​-tips/​deep-sky-with-your-dslr/​

https://​starizona.​com/​tutorial/​ccd-vs-dslr-astrophotography​/​

Index

A

Absolute magnitude

Absorption nebulae

Acceleration of expanding universe

Aeronomy of Ice in the Mesosphere (AIM)

Aft

Airglow

Airy Transit Circle

Almagest , the

Alpha Centauri

Altazimuth mounts

Altitude

Amateur astronomy

Andromeda Galaxy

Andromeda Nebula

Angled glass panels

Angled structures

Annularity

Annular solar eclipse

Antumbra

Apogee

Apollo

Apparent magnitude

Aristarchus

Aristotle

Asterism

Asteroid Belt

Asteroid Day

Asteroids

Astrology

Astronomical league

Astronomical objects of interest

Astronomical publications

Astronomical software

Astronomical unit

Astronomy

Astronomy clubs

Astronomy Magazines

Astronomy themed cruises

Astrophotographer’s eye

Astrophotography Logbook

Astrophysical Journal

Astrophysics

Astro Tip

Atlantic

Atoms

Attire policy

Aurora australis

Aurora borealis

Auroras

Autoguider

Autumnal equinox

Azamara Club Cruises

Azamara Journey

Azamara Quest

Azimuth

B

Baily’s Beads

Barlow lens

Barred spiral galaxy

Belt of Venus

BepiColombo

Beta Centauri

Bethe, H.

Big Bang

Big Dipper

Binary star system

Binoculars

Bioluminescence

Black dwarfs

Black holes

Blink comparator

Bolides

Bow

Bracing

Brahe, T.

Bridge

Bridge information channel

Burney, V.

C

Cabeus Crater

Cable release

California Institute of Technology

Camera control panel

Camera FV-5

Camera LCD

Camera viewfinder

CCD

Celestial Coordinates

Celestial equator

Celestial sphere

Center for NEO Studies (CNEOS)

Cepheid variable

Chandrasekhar limit

Chandra X-ray observatory

Chandra X-ray spacecraft

Chandrayaan-1

Chelyabinsk

Chicxulub

Chromosphere

Cleaning kit

Clementine

Coal sack

Cold War

Coma

Coma cluster of galaxies

Comet Hale Bopp

Comet Shoemaker-Levy 9

Comets

Commercial Lunar Payload Services (CLPS)

Compact system cameras (CSCs)

Compass

Computer

Computer/camera backpack

Consigliore

Constellations

Core

Corona

Cosmic Background Explorer (COBE)

Cosmic microwave background (CMB)

Cosmic web

Cosmological constant

Course

Crops

Cruise considerations

Cruise lines

Cruise terminal

Cunard

Cygnus X-1

D

Da Vinci glow

Da Vinci, L.

Daguerre, L.J.M.

Dark energy

Dark matter

Dark zones

De Revolutionibus Orbium Coelestium

Deck chair

Deck lighting

Deck plans

Deck railing

Declination

Destination lectures

Diamond ring

Dicke, R.

Digital single lens reflex (DSLR)

Dinosaurs

Disembarkation

Doppler effect

Doppler, J.C.

Doppler shift

Double-planet system

Draper, J.W.

Dust tail

Dwarf stars

E

Earth 2.0

Earthshine

Earth’s shadow

Eclipse maps

Eclipse plan

Ecliptic

Eddington, A.

Einstein, A.

Electrocardiogram (EKG)

Electromagnetic waves

Electron degeneration

Electrons

Elliptical galaxies

Embarkation

Emission nebulae

Equator

Equatorial mounts

Eratosthenes

Evening Star

Event horizons

Event Horizon Telescope (EHT)

Exoplanets

Exosphere

Eyeglasses

Eyepiece projection

F

False cross

Fermi spacecraft

Field of view (FOV)

File conversion

Fireballs

Fitness track

Focal reducer

Focus fuzz

Ford, K.

Forward

Frauenhofer, J.

Frauenhofer lines

Friedmann, A.

Full Dress Ship

G

Gaia

Galactic center

Galactic cluster

Galactic supercluster

Galilei, G.

Gamma rays

Geared tripod head

Gegenschein

Geminid meteor shower

Geocentric universe

Geocentrism

Giant molecular clouds (GMC)

Global Positional Satellites (GPS)

Globule

Goldie Locks Zone

Gravitational attractions

Gravitational contraction

Gravitational waves (GW)

Gravity

Gravity Recovery and Interior Laboratory (GRAIL)

Grazing lunar occultation

Great Attractor

Great Rift

Great Square

Green flash

Greenwich

Guiding eyepiece

Gyroscope

H

Hale, G.E.

Harriot, T.

Heavens above

Height of eye

Heliocentrism

Helipad

Helium

Helium-3

Herschel, W.

Hipparchus

Homo Erectus

Homo sapiens

Hooker telescope

Horizons

Horn antenna radio telescope

Hoyle, F.

Hubble classification scheme for galaxies

Hubble constant

Hubble, E.

Hubble’s law

Hubble Space Telescope (HST)

Huggins, Sir W.

Humason, M.

Hybrid solar eclipses

Hydrogen

Hydrostatic equilibrium

I

Image processing

Image processing software

Impact basins

Impact craters

Indian Ocean

Infinity

Infinity mark

Inflation

Infrared wavelengths

Interactive Google map

International Astronomical Union (IAU)

International Organization of Standardization (ISO)

International Reference Meridian (IRM)

International Space Station (ISS)

Internet

Ion tail

Iridium flares

Iridium satellites

Itinerary

J

James Webb space telescope (JWST)

Jet lag

Jupiter

Jupiter family of comets

K

Kepler, J.

Kepler’s Three Laws of Planetary Motion

Keycards

Kilonova

K-T boundary

Kuiper Belt

Kuiper Belt objects (KBOs)

Kuiper, G.

L

Ladder ways

Laniakea

Large Magellanic cloud (LMC)

Laser Interferometer Gravitational-Wave Observatory (LIGO)

Late Heavy Bombardment

Latitudes

Lava

LCD screen

Lemaître, G.

Lens hood

Lifeboat drill

Light avoidance

Light blocking

Lightning

Lightning safety

Light pollution

Light years

Lines of latitude

Lines of longitude

Little dipper

Live View

Local apparent noon

Local groups

Longitude

Long-period comets

Lowell Observatory

Low overheads

Luna

Lunar Atmosphere and Dust Environment Explorer (LADEE)

Lunar corona

Lunar Crater Remote Observation Sensing Satellite (LCROSS)

Lunar eclipses

Lunar halos

Lunar meteorites

Lunar month

Lunar occultation

Lunar Orbital Platform-Gateway

Lunar Prospector

Lunar Reconnaissance Orbiter (LRO)

Lunar water

M

Magellan, F.

Magic hours

Magmatic water

Magnetars

Main deck

Manuals

Manual setting

Mare Imbrium

Maria

Mars

Mather, J.

Medical facility

Medicines

Memory cards

Mercury

Meridian

Mesopause

Messenger

Metadata

Meteorites

Meteors

Meteor showers

Microwaves

Milkomeda

Milky Way

Milky Way Galaxy

Minor body orbit data

Minor planets

Monoculars

Moon

Moonbows

Moon dogs

Moonlight blue

Moonlight magic moment

Moon mineralogy mapper (M3)

Moon shadow

Morning Star

Motion in the ocean

Motorized mounts

Mount Palomar Observatory

Mount Wilson Observatory

Multi-Messenger astronomy

Multiverses

Muster Station

N

NASA eclipse web site

NASA lunar eclipse page

NASA solar eclipse page

National Air and Space Museum

National Oceanographic and Atmospheric Administration (NOAA)

Nautica

Nautical miles

Near Earth asteroids (NEAs)

Near Earth objects (NEOs)

Nebulae

Neptune

Neutrons

Neutron stars

New Horizons

New Moon

Newton, I.

NightCap Camera

Night vision

NOAA aurora 30 minutes forecasts

NOAA 3 day aurora forecasts

Nobel Prize

Noctilucent cloud (NLC)

Non-astronomical software

Noon

North celestial pole (NCP)

Northern Cross

Nova

Nuclear density

Nuclear fusion

Nucleus

O

Observable universe

Observer’s Handbook

Observing list

Oceania Cruise Line

Oceanus Procellarum

Oort Cloud

Oosterdam

Open camera

Opposition

Optical aid

Orion

Orion Nebula

P

Pacific Ocean

Parhelia

Parsecs

Parselenae

Partial lunar eclipse

Partial solar eclipse

Passageways

Path of annularity

Path of totality

Path of totality/annularity

Peebles, P.J.E.

Penumbra

Penumbral lunar eclipses

Penzias, A.

Perigee

Permanently shadowed regions

Perseid meteor shower

Philosophiae Naturalis Principia Mathematica

Photographic plate holder

Photosphere

Photo tip

Physical theory

Pinhole projection

Pirate condition

Planck mission

Planetary defense

Planetary defense coordination office

Planetary nebula

Planetesimals

Planisphere

Plasma

Platonic solids

Pleiades

Pluto

Pocket cameras

Polaris

Port

Port departure day

Port of call

Precise focus

Prime focus

Prime lens

Prime meridian

Primeval atom's

Primordial black holes

Prinsendam

Proto-planetary disk

Protostar

Proxima Centauri

Ptolemaic system

Ptolemy

Q

Quantum mechanics

Quantum theory of matter

Queen Victoria

R

Radiant

Radiative pressure

Radio telescopes

Rainbows

Raised steps

Ranger

RAW file

Reception desk

Redfern's Rules of Astrophotography

Red giant

Red giant stars

Red LED headband

Red shifts

Relative wind

Repositioning voyages

Right ascension

Rubin, V.

Rule 1

Rule 2

Rule 3

Rule 4

Rule 5

Rule 6

Rule 7

Rule 8

Rule 9

Rule 10

S

Safety of Life at Sea (SOLaS)

Safety tips

Sagittarius A*

Satellites

Saturn

Scutum star clouds

Sea Dream luxury yachts

Sea horizon

Seasons

Sea spray bow

Selene

Sextant

Shadow selfie

Shadow zones

Ship observatory

Ship’s anemometer

Ship’s daily schedule

Ships information channel

Ship’s mast

Ship’s navigation channel

Ship’s position

Ship studio

Ship tip

Ship’s wake

Shore excursions

Short-period comets

Sidereus Nuncius

Sigma Octans

Singularity

Sir Isaac Newton

Sirius

Sky and Telescope magazine

SkySafari Pro

Small Magellanic Cloud (SMC)

Smart phone

Smoot, G.

Software settings

Solar corona

Solar eclipse

Solar eclipse glasses

Solar eclipse safety notes

Solar filter

Solar flares

Solar halos

Solar magnetism

Solar mass

Solar maximum

Solar minimum

Solar prominences

Solar radiation pressure

Solar system

Solar transit

Solar viewing and solar photography safety

Solar wind

South celestial pole (SCP)

Southern Cross

Southern Ocean

South Pole-Aitken (SPA) basin

Spacetime

Space weather

Spectroscope

Spectroscopy

Spectrum

Speed

Spiral arms

Spiral galaxies

Spiral nebulae

Sporadic meteor

Spot the Station

Starboard

Star charts

Star cluster

Star parties

Star Pride

Starquake

Stars

Statendam

Stateroom

Stateroom number

Stellar masses

Stellar nucleosynthesis

Stern

String theory

Strong nuclear force

Sublimate

Suggested reading and links

Summer solstice

Summer Triangle

Sun

Sun dogs

Sunrises

Sunsets

Sunspot cycle

Super Earths

Supermassive black holes

Supernova

Supernova remnants

Surveyor

Synestia

T

Tablet

Telephoto lens

Telescopes

Terminator

Theia

Theory of General Relativity

Theory of Special Relativity

Tides

Time

Time zone

Tip

Tombaugh, C.

Top deck

Totality

Total lunar eclipse

Total solar eclipse

Transit

Transneptunian objects (TNOs)

Triangulum Galaxy

Tripod

Tripod safety

Tripod 3 way locking ball head

True wind

Tunguska

Type Ia/Ib supernova

Type II supernova

U

Ultima Thule

Umbra

Underway

Unidentified flying object (UFO)

Universal Date

Universal law of gravitation

Universal Time Coordinated (UTC)

Upper decks

Uranus

USSR

V

Venus

Vernal equinox

Video

Viewfinder

Virgo Supercluster

Visual astronomy

Vixen

W

Wavebows

Waves

Weather

Weather decks

Westerdam

White balance

White dwarfs

Wide field lens

WiFi

Wilkinson Microwave Anisotropy Probe (WMAP)

Wilson, R.

Winds

Windstar Cruises

Windstar luxury yachts

Winter solstice

World/grand voyages

X

X-rays

X-ray sources

Y

Yerkes Observatory

Z

Zenith

Zodiac

Zodiacal band

Zodiacal light

Zoom lens

Zwicky, F.