The Sky at Night

The Sky at Night

Easy Enjoyment from Your Backyard

Tim B. Hunter

The University of Arizona Press

www.uapress.arizona.edu

We respectfully acknowledge the University of Arizona is on the land and territories of Indigenous peoples. Today, Arizona is home to twenty-two federally recognized tribes, with Tucson being home to the O’odham and the Yaqui. Committed to diversity and inclusion, the University strives to build sustainable relationships with sovereign Native Nations and Indigenous communities through education offerings, partnerships, and community service.

© 2023 by The Arizona Board of Regents

All rights reserved. Published 2023

ISBN-13: 978-0-8165-4812-5 (paperback)

ISBN-13: 978-0-8165-4813-2 (ebook)

Cover design by Leigh McDonald

Cover photo by tengyart/Unsplash

Designed and typeset by Leigh McDonald in Adobe Caslon Pro 10.5/14, Millimetre by Jérémy Landes (Velvetyne Type Foundry) and Interstate (display)

Unless otherwise noted, all images are the author’s.

Content of this book is based on Tim Hunter’s Sky Spy columns, published in the Arizona Daily Star beginning in 2007.

Library of Congress Cataloging-in-Publication Data

Names: Hunter, Tim B., author.

Title: The sky at night : easy enjoyment from your backyard / Tim B. Hunter.

Description: Tucson : University of Arizona Press, 2023. | Includes bibliographical references and index.

Identifiers: LCCN 2022015966 (print) | LCCN 2022015967 (ebook) | ISBN 9780816548125 (paperback) | ISBN 9780816548132 (ebook)

Subjects: LCSH: Amateur astronomy. | Astronomy—Popular works. | Astronomy—Observers’ manuals.

Classification: LCC QB44.3 .H86 2023 (print) | LCC QB44.3 (ebook) | DDC 520—dc23/eng20220901

LC record available at https://lccn.loc.gov/2022015966

LC ebook record available at https://lccn.loc.gov/2022015967

Printed in the United States of America

♾ This paper meets the requirements of ANSI/NISO Z39.48-1992 (Permanence of Paper).

✨

This book is dedicated to my dear wife, Carol, who allows me to let my hobby of amateur astronomy run amok. It is also dedicated to my grandchildren Braeden Chhatpar and Amelia Chhatpar. May they come to love the sky as much as I do and remember me fondly someday when they are looking at Orion the Hunter, Scorpius the Scorpion, or a crescent Moon nearby ever-brilliant Venus.

Contents

Preface

1. Amateur Astronomy

2. The Moon

3. The Planets

4. Stars

5. Constellations

6. Other Wonders of the Night

7. The Seasons and the Calendar

8. Selected Famous Astronomers, Events, and Places

9. What I Learned from Writing an Astronomy Column

10. What Telescope Should You Buy?

Acknowledgments

Astronomical Resources

Glossary

Selected Bibliography

Index

Preface

Ihave been an amateur astronomer since 1950 when Miss Wilmore, my first-grade teacher, showed me a book of the constellations. I was fascinated by a drawing of Cygnus the Swan and wondered whether I could ever see that in the sky. As the years passed, my interest in astronomy grew. I got a Criterion four-inch Dynascope reflecting telescope when I was in eighth grade. I had saved up $50 from mowing lawns. My father helped me set it up, and I used it for many years off and on through high school, college, and medical school. In 1970, while I was serving in Vietnam, my parents gave my Dynascope to a boy down the street thinking I no longer wanted it or would use it. I often wonder what happened to that telescope and the boy.

My astronomy interest was always there, though I did not want to become a professional astronomer. I wanted to become a physician like my paternal grandfather, who was a pathologist. I graduated from Northwestern Medical School in 1968 and eventually became a radiologist after finishing my radiology training in 1974 at the University of Michigan in Ann Arbor.

Through all of this my interest in astronomy never went away, though it was somewhat on hold and only blossomed again when I moved to Tucson, Arizona, in January 1975 to become a faculty member of the Department of Radiology at the University of Arizona. Tucson likes to claim it is the Astronomy Capital of the World, and I agree. I joined the Tucson Amateur Astronomy Association, Inc. (TAAA) and became very active observing the sky, trying astrophotography, and attending local and national astronomical meetings and events.

Even though medicine was a wonderful career, I wondered whether I should have tried to become a professional astronomer or maybe even an astronaut. In the summer of 1976, I met Frank, a graduate student completing a PhD in engineering. He had a master’s degree in astronomy from the University of Chicago, and I asked him why he switched to engineering from astronomy. Frank told me there were few jobs in professional astronomy, and he realized it was best to enjoy astronomy as an avocation rather than as a vocation. This got me thinking. I realized I was much better off enjoying astronomy as a hobby rather than as a vocation. I would have been no good as a professional astronomer, certainly not good enough to win a lot of grants or observing time on large professional telescopes. I had the best of all worlds: a great, satisfying career, and an ever-challenging and enjoyable hobby.

In January 2007, I received a call from Inger Sandal, editor of Caliente, the Thursday insert in the Arizona Daily Star that tells the public what to do about town, where to dine, what shows to see, and what adventures out of town to anticipate. She wanted to know if I would be interested in writing the Sky Spy column for each weekly edition of Caliente. This column had been started more than twenty years previously by Michael Smith, MD, a highly respected neurologist and amateur astronomer. I had known Mike for many years through our membership in the TAAA, as well as from his training at University Medical Center, the academic hospital for the College of Medicine at the University of Arizona.

Mike started Sky Spy on his own initiative, writing to the editor of the Arizona Daily Star and suggesting an astronomy column for the public. I don’t know if he came up with the name Sky Spy, but he wrote a splendid column for nineteen years. I read it faithfully every week when it came out. After Mike, the column was continued by one of the paper’s reporters, who did a very fine job with it for seven years until he left the Arizona Daily Star to become the food editor of the rival newspaper, the Tucson Citizen.

Inger Sandal, the editor of Caliente, was in immediate need of a writer for the column when she called me. I certainly was not on anyone’s horizon as a noted astronomy columnist. Inger first asked David Levy, the popular author and comet discoverer, if he would like to write the column. He declined because he had his own column Star Trails in Sky and Telescope magazine, as well as many other ongoing writing projects and commitments. David is a very dear friend of mine and he suggested Inger call me.

I was certainly intrigued by Inger’s offer, but I didn’t know if I was up to the job. She kindly provided me with several recent Sky Spy columns to give me a perspective on what they contained and what she wanted. Then, I worked furiously that afternoon, stealing a bit of university time for my outside interest, writing a couple of sample columns that I sent to her. She liked them and suggested we proceed. On February 1, 2007, my first Sky Spy column was published.

Initially, the column was three hundred words and contained an illustration that I drew digitally using Photoshop and various digital star atlases. My illustrations were designed to show what the observer would see when looking in one direction or another. Sometimes, I submitted a photograph with the column. I fancy myself an astrophotographer, and a few of my astrophotographs were wide-field night sky images that would complement a particular column. Fortunately, Inger accepted almost all of my photographs, so I had a good place to publish some of my images that otherwise would not have found a home for publication.

Over time, illustrations were no longer used with the columns except on those rare occasions when I submitted an astrophotograph that I thought was particularly appropriate for a column. Some years after I started, Inger asked me if I could write the columns twice a month rather than weekly, as the newspaper wanted to save a bit of column print space. Instead, I proposed that it continue weekly, but reduced to 250 words so as not to lose reader interest. This worked well, and up to the present time (2022) the column has been published weekly with approximately 250 words per column.

I have now over 750 columns, and this book is a compilation of them. They have not just been thrown all together and published as a book. I have picked and chosen the important points from the columns and collated them, I hope, into an intelligible whole to be enjoyed by the reader. Terms that appear in the glossary are in bold when they first appear, while other key terms are in italics when they first appear.

The sky is wonderful. It is to be enjoyed day and night, with easy viewing of the night sky the focus of this book. I assume you, the reader, are literate and interested in the sky, but are not particularly knowledgeable. Emphasis is on naked-eye viewing, with an occasional reference to using binoculars or a small, low-power telescope. I assume you are not familiar with most of the constellations, but I hope the descriptions and the directions I provide are good enough to help you find your way around the sky. I will have succeeded if you enjoy the sky as much as I do and make friends with the Moon, planets, and stars.

The Sky at Night

1

Amateur Astronomy

Icall everyone who reads this book an amateur astronomer, a lover of the night sky. You can take the sky in as much or as little as you want. Some amateur astronomers have a PhD in astronomy and related sciences and do astronomy professionally for money. Many others like to walk outside at night occasionally to see something interesting, but otherwise are not bothered by astronomical thoughts. Either way is fine with me.

I like the Moon for its beauty and intrigue. I also like to use it as a pointer to other celestial objects. Everyone can find the Moon. If something is close to it, the Moon is an excellent guide to that object.

In this book, all of the material is applicable to almost any observing location in the Northern Hemisphere. Many of the observing tips, astronomical definitions, and other descriptions apply to both the Northern and Southern Hemispheres, but the constellations and other phenomena described herein are best seen in the Northern Hemisphere. Date-specific or location-specific phenomena, such as solar or lunar eclipses, are not mentioned except in general terms as part of a wider discussion of the sky.

Any time of day or night is fair game for an observing session, though there is an emphasis on early evening viewing, often in the evening twilight, as that is more convenient for most people. However, one should not shy away from the predawn sky, and sometimes it is necessary to be up in the middle of the night to see something interesting or unusual.

Sleep deprivation is definitely a worry for an amateur astronomer. Some of the best astronomical events happen in the middle of the night on a work night or a school night. You either can lose sleep or miss the event. While amateur astronomy cannot be considered a hazardous hobby, it is not without risks. If one is tired and sleep deprived, it is easy to fall off a ladder while looking through a telescope or to walk into sharp objects in the dark.

Driving home in the morning after being up all night observing can be very dangerous not only to the astronomer but also to his or her passengers and other motorists. You must use your common sense and make sure you do not attempt to work, operate dangerous machinery, or drive while sleep deprived. In addition, alcohol and smoking are not good for observing.

Observing Aids

How does one learn the constellations, planets, and important bright stars? With patience and practice. Observing aids are helpful. The best observing aid by far is a knowledgeable friend or family member who shows you the sky.

Planisphere

Beyond a helpful family member or friend, by far the most useful aid for learning the night sky is a planisphere (figure 1.1).

This is a cardboard or plastic chart showing the constellations. The chart rotates inside of a square or rectangular border that is labeled with the time and date. To use a planisphere, you take it outside and hold it up overhead and orient it north–south and east–west according to its directions. Dial in the present time and date. The planisphere chart shows you the constellations currently visible. By looking back and forth between the planisphere and the sky, you can rapidly recognize constellations and prominent stars. Planispheres cost $10–$30 and may be purchased from many bookstores and online vendors. They are invaluable. I use one all of the time.

Figure 1.1. Planisphere.

Mobile Apps

What about mobile apps that show the sky? They are great, and I have several of them on my phone. However, I don’t find them as useful as a planisphere. Even the biggest cell phone or tablet is nowhere near as large as a typical planisphere and does not give the overview and field of view of a planisphere. However, mobile apps are great for identifying a specific bright object, such as a planet, as planispheres are not useful for finding them. Carefully point the cell phone at the object in question, and a good app will identify what it is. You must be most careful with your aim. Mobile apps are up-to-date for time and location and are superb for identifying the planets as well as bright stars.

Use whatever works best for you, a planisphere or a mobile app. Or better yet, both.

Binoculars

Binoculars are wonderful for sky viewing. What is even better is to have a tripod to steady the binoculars if they are above 8–10 power or are heavy. I won’t recommend a specific brand other than to say you should choose a pair that is easy to hold and works well during the day for watching a football game or for bird-watching. The binocular tripod is most convenient when you want to study an object, such as the moons of Jupiter or the large Beehive star cluster, beyond just glancing at it.

I would not exceed 7 or 8 power binoculars for most observing. Higher-power binoculars or very large binoculars with objective lenses larger than 50 mm in diameter are quite fine for observing fainter celestial objects. They cannot be held for long by hand due to their weight, and their higher power magnifies any vibration or unsteadiness in holding them, thereby ruining most observing sessions. They require a good heavy-duty tripod for steadiness and ease of use and are more expensive.

Telescopes

The Sky Spy columns and this book are predicated on the notion that you do not own a telescope or have access to one. There is an occasional reference to viewing something with a small, low-power telescope, but one can spend a lifetime enjoying the sky with only naked-eye observing.

A common mistake is to buy a cheap