Astronomy For Dummies

371 Pages·2012·31.7 MB·English

by  Stephen P. Maran

Astronomy

FOR

DUMmIES

‰

3RD EDITION

by Stephen P. Maran, PhD

Astronomy

FOR

DUMmIES

‰

3RD EDITION

Astronomy For Dummies®, 3rd Edition
Published by
John Wiley & Sons, Inc.
111 River St.
Hoboken, NJ 07030-5774
www.wiley.com

Copyright © 2013 by John Wiley & Sons, Inc., Hoboken, New Jersey

Published simultaneously in Canada

No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or
by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except as permit-
ted under Sections 107 or 108 of the 1976 United States Copyright Act, without the prior written permis-
sion of the Publisher. Requests to the Publisher for permission should be addressed to the Permissions
Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, [phone], fax (201) 748-
6008, or online at www.wiley.com/go/permissions.

Trademarks: Wiley, the Wiley logo, For Dummies, the Dummies Man logo, A Reference for the Rest of Us!,
The Dummies Way, Dummies Daily, The Fun and Easy Way, Dummies.com, Making Everything Easier, and
related trade dress are trademarks or registered trademarks of John Wiley & Sons, Inc., and/or its affili-
ates in the United States and other countries, and may not be used without written permission. All other
trademarks are the property of their respective owners. John Wiley & Sons, Inc., is not associated with
any product or vendor mentioned in this book.

LIMIT OF LIABILITY/DISCLAIMER OF WARRANTY: THE PUBLISHER AND THE AUTHOR MAKE NO
REPRESENTATIONS OR WARRANTIES WITH RESPECT TO THE ACCURACY OR COMPLETENESS OF
THE CONTENTS OF THIS WORK AND SPECIFICALLY DISCLAIM ALL WARRANTIES, INCLUDING WITH-
OUT LIMITATION WARRANTIES OF FITNESS FOR A PARTICULAR PURPOSE. NO WARRANTY MAY BE
CREATED OR EXTENDED BY SALES OR PROMOTIONAL MATERIALS. THE ADVICE AND STRATEGIES
CONTAINED HEREIN MAY NOT BE SUITABLE FOR EVERY SITUATION. THIS WORK IS SOLD WITH THE
UNDERSTANDING THAT THE PUBLISHER IS NOT ENGAGED IN RENDERING LEGAL, ACCOUNTING, OR
OTHER PROFESSIONAL SERVICES. IF PROFESSIONAL ASSISTANCE IS REQUIRED, THE SERVICES OF
A COMPETENT PROFESSIONAL PERSON SHOULD BE SOUGHT. NEITHER THE PUBLISHER NOR THE
AUTHOR SHALL BE LIABLE FOR DAMAGES ARISING HEREFROM. THE FACT THAT AN ORGANIZA-
TION OR WEBSITE IS REFERRED TO IN THIS WORK AS A CITATION AND/OR A POTENTIAL SOURCE
OF FURTHER INFORMATION DOES NOT MEAN THAT THE AUTHOR OR THE PUBLISHER ENDORSES
THE INFORMATION THE ORGANIZATION OR WEBSITE MAY PROVIDE OR RECOMMENDATIONS IT
MAY MAKE. FURTHER, READERS SHOULD BE AWARE THAT INTERNET WEBSITES LISTED IN THIS
WORK MAY HAVE CHANGED OR DISAPPEARED BETWEEN WHEN THIS WORK WAS WRITTEN AND
WHEN IT IS READ.

For general information on our other products and services, please contact our Customer Care
Department within the U.S. at 877-762-2974, outside the U.S. at 317-572-3993, or fax [phone].

For technical support, please visit www.wiley.com/techsupport.

Wiley publishes in a variety of print and electronic formats and by print-on-demand. Some material
included with standard print versions of this book may not be included in e-books or in print-on-demand.
If this book refers to media such as a CD or DVD that is not included in the version you purchased, you
may download this material at http://booksupport.wiley.com. For more information about Wiley
products, visit www.wiley.com.

Library of Congress Control Number: 2012948997

ISBN 978-1-118-37697-3 (pbk); ISBN 978-1-118-37694-2 (ebk); ISBN 978-1-118-37695-9 (ebk);
ISBN 978-1-118-37696-6 (ebk)

Manufactured in the United States of America

10 9 8 7 6 5 4 3 2 1

About the Author

Stephen P. Maran, PhD, a 36-year veteran of the space program, has been
honored with the NASA Medal for Exceptional Achievement. He received
the Klumpke-Roberts Award of the Astronomical Society of the Pacific for
“outstanding contributions to the public understanding and appreciation of
astronomy,” the George Van Biesbroeck Prize of the American Astronomical
Society, for “long-term extraordinary or unselfish service to astronomy,”
and the Andrew W. Gemant Award of the American Institute of Physics for
“significant contributions to the cultural, artistic, or humanistic dimension of
physics.”

In 2000, the International Astronomical Union named an asteroid (Minor
Planet 9768) “Stephenmaran” for Dr. Maran.

Dr. Maran began practicing astronomy from rooftops in Brooklyn and at a
deserted golf course in the far reaches of the Bronx. He graduated to conduct
professional research with telescopes at the Kitt Peak National Observatory
in Arizona, the National Radio Astronomy Observatory in West Virginia,
the Palomar Observatory in California, and the Cerro Tololo Inter-American
Observatory in Chile. He also conducted research with instruments in space,
including the Hubble Space Telescope and the International Ultraviolet
Explorer. He helped design and develop two instruments that flew in space
aboard Hubble.

He’s also taught astronomy at the University of California, Los Angeles, and
the University of Maryland, College Park. As press officer of the American
Astronomical Society for many years, he presided over media briefings that
brought news of astronomical discoveries to people worldwide.

Dr. Maran observed total eclipses of the sun from the Gaspé Peninsula and
elsewhere in Quebec; Baja California in Mexico; the Sahara desert in Libya;
at sea off New Caledonia and Singapore in the eastern Pacific; and the shores
of the U.S.

In the course of spreading the good word about astronomy, Maran has
lectured on black holes in a bar in Tahiti and explained an eclipse of the
sun on NBC’s show. He’s also spoken on eclipse and comet cruises aboard
Cunard’s and Sitmar Line’s , and MSC Cruises’ Sinfonia. He’s addressed
audiences ranging from inner-city Seattle school children and Atherton,
California, Girl Scouts to the National Academy of Engineering in Washington,
D.C. and subcommittees of both the U.S. House of Representatives and the
U.N. Committee on the Peaceful Uses of Outer Space.

Dr. Maran is editor of and has co-authored or edited ten other books on
those subjects, including two recent works written jointly with Laurence A.
Marschall, and He has written many articles for and magazines and served
as a writer and consultant for the National Geographic Society and Time-Life
Books.

Dr. Maran is a graduate of Stuyvesant High School in New York City (where
he served a full season on the Math Team without incurring serious injury)
and of Brooklyn College. He received both his MA and PhD in astronomy
from the University of Michigan. Maran is married to Sally Scott Maran, a
journalist. They have three children.

Dedication

To Sally, Michael, Enid, and Elissa with all my love.

Author’s Acknowledgments

Thanks first to my family and friends who put up with me in the writing of
this book. Thanks also to my agent, Skip Barker, who goaded and guided me
in this project, and to Stacy Collins for her faith in the original project and
Lindsay Lefevre for championing this substantially revised edition.

I’m grateful to Ron Cowen and Dr. Seth Shostak for their past contributions
to this book; to Kathy Cox, Georgette Beatty, Josh Dials, and Jennifer Moore,
who organized and edited it; and to their skilled colleagues on the editorial
and production teams at Wiley Publishing who made the book better and
brighter. A special thanks to Laurence Marschall for suggestions that
improved the accuracy and thoroughness of the book.

Thanks as well to the organizations that provided the photographs in this
book and to the producer of the star maps, Robert Miller.

I’m grateful for helpful advice from several experts for this new edition,
particularly to Prof. Richard Mushotzky on black holes, Drs. Marc Kuchner
and Rory Barnes on exoplanets, and Dr. Shostak on the search for
extraterrestrial intelligence.

Some drawings in this book have been inspired by Dr. Dinah L. Moche and
her excellent book, also published by Wiley. Dr. Moche deserves many
thanks for her support of this book and for her dedication to making the
science of astronomy accessible to anyone.

Publisher’s Acknowledgments

We’re proud of this book; please send us your comments at http://dummies.custhelp.com.
For other comments, please contact our Customer Care Department within the U.S. at 877-762-2974,
outside the U.S. at 317-572-3993, or fax [phone].

Some of the people who helped bring this book to market include the following:

Acquisitions, Editorial, and Vertical
Websites

Project Editor: Jennifer Moore

Acquisitions Editor: Lindsay Lefevre

Copy Editor: Krista Hansing

Assistant Editor: David Lutton

Editorial Program Coordinator: Joe Niesen

Technical Editor: Laurence A. Marschall

Editorial Manager: Carmen Krikorian

Senior Editorial Manager: Jennifer Ehrlich

Editorial Assistants: Alexa Koschier and

Rachelle Amick

Art Coordinator: Alicia B. South

Cover Photos:

Cartoons: Rich Tennant

(www.the5thwave.com)

Composition Services

Project Coordinator: Sheree Montgomery

Layout and Graphics: Corrie Niehaus

Proofreader: Toni Settle

Indexer: Joan Griffitts

Publishing and Editorial for Consumer Dummies

Kathleen Nebenhaus, Vice President and Executive Publisher

David Palmer, Associate Publisher

Kristin Ferguson-Wagstaffe, Product Development Director

Publishing for Technology Dummies

Andy Cummings, Vice President and Publisher

Composition Services

Debbie Stailey, Director of Composition Services

Contents at a Glance

Introduction ................................................................ 1

Part I: Stalking the Cosmos .......................................... 5

Chapter 1: Seeing the Light: The Art and Science of Astronomy .................................7
Chapter 2: Join the Crowd: Skywatching Activities and Resources ..........................27
Chapter 3: The Way You Watch Tonight: Terrific Tools for Observing the Skies ......45
Chapter 4: Just Passing Through: Meteors, Comets, and Artificial Satellites ..........65
Part II: Going Once Around the Solar System ............... 85

Chapter 5: A Matched Pair: Earth and Its Moon ..........................................................87
Chapter 6: Earth’s Near Neighbors: Mercury, Venus, and Mars ..............................109
Chapter 7: Rock On: The Asteroid Belt and Near-Earth Objects .............................129
Chapter 8: Great Balls of Gas: Jupiter and Saturn ......................................................139
Chapter 9: Far Out! Uranus, Neptune, Pluto, and Beyond ........................................151
Part III: Meeting Old Sol and Other Stars .................. 161

Chapter 10: The Sun: Star of Earth ..............................................................................163
Chapter 11: Taking a Trip to the Stars ........................................................................187
Chapter 12: Galaxies: The Milky Way and Beyond ....................................................217
Chapter 13: Digging into Black Holes and Quasars ...................................................241
Part IV: Pondering the Remarkable Universe ............. 255

Chapter 14: Is Anybody Out There? SETI and Planets of Other Suns .....................257
Chapter 15: Delving into Dark Matter and Antimatter ..............................................277
Chapter 16: The Big Bang and the Evolution of the Universe ..................................289
Part V: The Part of Tens ........................................... 301

Chapter 17: Ten Strange Facts about Astronomy and Space ...................................303
Chapter 18: Ten Common Errors about Astronomy and Space ..............................307

Part VI: Appendixes ................................................. 311

Appendix A: Star Maps ..................................................................................................313
Appendix B: Glossary ....................................................................................................321
Index ...................................................................... 325

Table of Contents

Introduction ................................................................. 1

About This Book ..............................................................................................2
Conventions Used in This Book .....................................................................2
What You’re Not to Read ................................................................................2
Foolish Assumptions .......................................................................................3
Icons Used in This Book .................................................................................3
Where to Go from Here ...................................................................................4

Part I: Stalking the Cosmos ........................................... 5

Chapter 1: Seeing the Light: The Art and Science of Astronomy . . . . . .7

Astronomy: The Science of Observation ......................................................8
What You See: The Language of Light ..........................................................9

They wondered as they wandered: Understanding

planets versus stars .................................................................................10

If you see a Great Bear, start worrying: Naming stars

and constellations ............................................................................10

What do I spy? Spotting the Messier Catalog and

other sky objects ..............................................................................18

The smaller, the brighter: Getting to the root of magnitudes ........19
Looking back on light-years ................................................................20
Keep on moving: Figuring the positions of the stars.......................21

Gravity: A Force to Be Reckoned With ........................................................25
Space: A Commotion of Motion ...................................................................26

Chapter 2: Join the Crowd: Skywatching Activities
and Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27

You’re Not Alone: Astronomy Clubs, Websites, Smartphone

Apps, and More ..........................................................................................28

Joining an astronomy club for star-studded company ...................28
Checking websites, magazines, software, and apps ........................30

Visiting Observatories and Planetariums ...................................................33

Ogling the observatories.....................................................................34
Popping in on planetariums ...............................................................36

Vacationing with the Stars: Star Parties, Eclipse Trips,

Dark Sky Parks, and More .........................................................................37

Party on! Attending star parties .........................................................37
Getting festive at an AstroFest ...........................................................38

Astronomy For Dummies, 3rd Edition
xii

To the path of totality: Taking eclipse cruises and tours ...............39
Motoring to telescope motels ............................................................41
Setting up camp at dark sky parks ....................................................42

Chapter 3: The Way You Watch Tonight: Terrific Tools
for Observing the Skies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45

Seeing Stars: A Sky Geography Primer ........................................................46

As Earth turns . . . ................................................................................46
. . . keep an eye on the North Star ......................................................48

Beginning with Naked-Eye Observation .....................................................50
Using Binoculars or a Telescope for a Better View ...................................53

Binoculars: Sweeping the night sky ...................................................53
Telescopes: When closeness counts .................................................57

Planning Your First Steps into Astronomy .................................................63

Chapter 4: Just Passing Through: Meteors, Comets,
and Artificial Satellites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65

Meteors: Wishing on a Shooting Star ..........................................................65

Spotting sporadic meteors, fireballs, and bolides ...........................67
Watching a radiant sight: Meteor showers .......................................69

Comets: The Lowdown on Dirty Ice Balls ...................................................74

Making heads and tails of a comet’s structure ................................75
Waiting for the “comets of the century” ...........................................78
Hunting for the great comet ...............................................................80

Artificial Satellites: Enduring a Love–Hate Relationship ..........................82

Skywatching for artificial satellites ....................................................83
Finding satellite viewing predictions ................................................84

Part II: Going Once Around the Solar System ................ 85

Chapter 5: A Matched Pair: Earth and Its Moon . . . . . . . . . . . . . . . . . . .87

Putting Earth under the Astronomical Microscope .......................................88

One of a kind: Earth’s unique characteristics .......................................88
Spheres of influence: Earth’s distinct regions ..................................89

Examining Earth’s Time, Seasons, and Age ................................................93

Orbiting for all time .............................................................................93
Tilting toward the seasons .................................................................95
Estimating Earth’s age .........................................................................97

Making Sense of the Moon ............................................................................98

Get ready to howl: Identifying phases of the Moon.........................99
In the shadows: Watching lunar eclipses .......................................100
Hard rock: Surveying lunar geology ................................................102
Quite an impact: Considering a theory about

the Moon’s origin ...........................................................................106

xiii
Table of Contents

Chapter 6: Earth’s Near Neighbors: Mercury, Venus, and Mars . . . .109

Mercury: Weird, Hot, and Mostly Metal ...................................................109
Dry, Acidic, and Hilly: Steering Clear of Venus ........................................111
Red, Cold, and Barren: Uncovering the Mysteries of Mars ....................113

Where has all the water gone? .........................................................113
Does Mars support life? ....................................................................115

Differentiating Earth through Comparative Planetology ........................117
Observing the Terrestrial Planets with Ease ...........................................118

Understanding elongation, opposition, and conjunction .............119
Viewing Venus and its phases ..........................................................122
Watching Mars as it loops around ...................................................124
Outdoing Copernicus by observing Mercury .................................127

Chapter 7: Rock On: The Asteroid Belt and Near-Earth Objects . . . .129

Taking a Brief Tour of the Asteroid Belt ...................................................129
Understanding the Threat That Near-Earth Objects Pose .....................132

When push comes to shove: Nudging an asteroid ........................134
Forewarned is forearmed: Surveying NEOs to protect Earth .......135

Searching for Small Points of Light ...........................................................136

Helping to track an occultation ........................................................137
Timing an asteroidal occultation .....................................................138

Chapter 8: Great Balls of Gas: Jupiter and Saturn . . . . . . . . . . . . . . . .139

The Pressure’s On: Journeying Inside Jupiter and Saturn .....................139
Almost a Star: Gazing at Jupiter .................................................................140

Scanning for the Great Red Spot ......................................................142
Shooting for Galileo’s moons ...........................................................143

Our Main Planetary Attraction: Setting Your Sights on Saturn .............146

Ringing around the planet ................................................................147
Storm chasing across Saturn ............................................................148
Monitoring a moon of major proportions .......................................148
Making sense of a cryptic moon ......................................................149

Chapter 9: Far Out! Uranus, Neptune, Pluto, and Beyond . . . . . . . . . .151

Breaking the Ice with Uranus and Neptune ..............................................151

Bull’s-eye! Tilted Uranus and its features .......................................152
Against the grain: Neptune and its biggest moon ..........................153

Meeting Pluto, Planet or Not ......................................................................154

The moon chip doesn’t float far from the planet ...........................155
Little Pluto compared to some big moons .....................................156

Buckling Down to the Kuiper Belt .............................................................156
Viewing the Outer Planets ..........................................................................157

Sighting Uranus ..................................................................................158
Distinguishing Neptune from a star .................................................158
Straining to see Pluto ........................................................................159