00 1981 FM 6/11/01 9:55 AM Page i Astronomy Second Edition by Christopher De Pree and Alan Axelrod A Pearson Education Company 00 1981 FM 6/11/01 9:55 AM Page ii To my girls, Julia, Claire, and Madeleine (CGD) For my stars, Anita and Ian (AA) Copyright © 2001 by The Ian Samuel Group, Inc. All rights reserved. No part of this book shall be reproduced, stored in a retrieval sys- tem, or transmitted by any means, electronic, mechanical, photocopying, recording, or otherwise, without written permission from the publisher. No patent liability is as- sumed with respect to the use of the information contained herein. Although every precaution has been taken in the preparation of this book, the publisher and authors assume no responsibility for errors or omissions. Neither is any liability assumed for damages resulting from the use of information contained herein. For information, ad- dress Alpha Books, 201 West 103rd Street, Indianapolis, IN 46290. THE COMPLETE IDIOT’S GUIDE TO and Design are registered trademarks of Pearson Education, Inc. International Standard Book Number:1-5925-7003-8 Library of Congress Catalog Card Number: 2001091092 03020187654321 Interpretation of the printing code: The rightmost number of the first series of num- bers is the year of the book’s printing; the rightmost number of the second series of numbers is the number of the book’s printing. For example, a printing code of 01-1 shows that the first printing occurred in 2001. Printed in the United States of America Note:This publication contains the opinions and ideas of its authors. It is intended to provide helpful and informative material on the subject matter covered. It is sold with the understanding that the authors and publisher are not engaged in rendering profes- sional services in the book. If the reader requires personal assistance or advice, a com- petent professional should be consulted. The authors and publisher specifically disclaim any responsibility for any liability, loss, or risk, personal or otherwise, which is incurred as a consequence, directly or in- directly, of the use and application of any of the contents of this book. Making or distributing electronic copies of this book constitutes copyright infringement and could subject the infringer to criminal and civil liability 00 1981 FM 6/11/01 9:55 AM Page iii Publisher Marie Butler-Knight Product Manager Phil Kitchel Managing Editor Jennifer Chisholm Acquisitions Editor Mike Sanders Development Editor Amy Gordon Production Editor Billy Fields Copy Editor Amy Lepore Illustrator Brian Moyer Cover Designers Mike Freeland Kevin Spear Book Designers Scott Cook and Amy Adams of DesignLab Indexer Lisa Wilson Layout/Proofreading Angela Calvert Svetlana Dominguez Mary Hunt Gloria Schurick 00 1981 FM 6/11/01 9:55 AM Page iv Contents at a Glance Part 1: Finding Our Place in Space 1 1 Naked Sky, Naked Eye: Finding Your Way in the Dark 3 Finding your way around the night sky. No telescope necessary. 2 Ancient Evenings: The First Watchers 17 What the ancient astronomers saw, thought, and said. 3 The Unexplained Motions of the Heavens 31 Puzzles of planetary motion: early thoughts on the subject. 4 Astronomy Reborn: 1543–1687 47 Everything (well, not really) you need to know about Copernicus, Tycho Brahe, Kepler, Galileo, and Newton. Part 2: Now You See It (Now You Don’t) 63 5 The Art of Collecting Light (with a Telescope) 65 Telescopes: what they see and how they work. 6You and Your Telescope 81 A guide to choosing and using binoculars and telescopes. 7 Over the Rainbow 101 Electromagnetic radiation: what it is, how it travels, and what it does. 8 Seeing in the Dark 117 Alternatives to visible-light astronomy: radio, infrared, ultraviolet, and high energy. 9 Space Race: From Sputnik to the International Space Station 131 A brief history of space exploration. Part 3: A Walk Around the Block 147 10 The Moon: Our Closest Neighbor 149 All about Earth’s moon. 11 Solar System Home Movie 161 How our solar system was born and developed. 12 Solar System Family Snapshot 173 A tour through our solar system. 13 So Close and Yet So Far: The Inner Planets 189 The lowdown on Mercury, Venus, and Mars. 00 1981 FM 6/11/01 9:55 AM Page v 14 Great Balls of Gas! The Outer Planets 205 All about Uranus, Neptune, Jupiter, and Saturn. 15 The Far End of the Block 221 The moons and rings of the jovian planets, and the story of Pluto. Part 4: To the Stars 235 16 Our Star 237 We explore the sun. 17 Of Giants and Dwarfs: Stepping Out into the Stars 251 Observing, measuring, and classifying stars. 18 Stellar Careers 267 How stars evolve—and how they end their lives. 19 Black Holes: One-Way Tickets to Eternity 279 Stellar endgames: neutron stars, black holes, and the strange effects they produce. 20 Stellar Nurseries 289 How stars are created. Part 5: Way Out of This World 301 21 The Milky Way: Much More Than a Candy Bar 303 A tour of our home Galaxy. 22 A Galaxy of Galaxies 317 Observing, measuring, and classifying galaxies. 23 Moving Out of Town 331 Active versus normal galaxies: Seyfert and radio galaxies, plus quasars. Part 6: The Big Questions 341 24 Table for One? 343 The odds on life beyond Earth and on other civilizations in the Milky Way. 25 What About the Big Bang? 359 How it all began (we think). 26 (How) Will It End? 369 Is the universe infinite or finite? Eternal or mortal? Will it end—and if so, how? 00 1981 FM 6/11/01 9:55 AM Page vi Appendixes A Star Words Glossary 379 A glossary of astronomy. B Upcoming Eclipses 395 A list of lunar and solar eclipses to watch for. C The Constellations 397 A complete list of the constellations with their approxi- mate positions. D The Messier Catalog 401 The classic list of deep-sky objects—available to amateur astronomers. E Sources for Astronomers 407 Key sources of information, including books, guides, charts, astronomical event calendars, and Internet resources. Index 413 00 1981 FM 6/11/01 9:55 AM Page vii Contents Part 1: Finding Our Place in Space 1 1 Naked Sky, Naked Eye: Finding Your Way in the Dark 3 Sun Days ........................................................................................3 Flat Earth, Big Bowl ........................................................................4 Man in the Moon............................................................................5 Lights and Wanderers ....................................................................7 Celestial Coordinates ......................................................................7 Measuring the Sky ..........................................................................9 The Size of Things, or “I Am Crushing Your Head!”........................9 Celestial Portraits..........................................................................11 The Dippers First ..........................................................................12 The Stars of Spring ......................................................................13 Summer Nights ............................................................................13 Fall Constellations........................................................................14 Winter Skies ................................................................................15 Who Cares? ..................................................................................16 2 Ancient Evenings: The First Watchers 17 A Dragon Eats the Sun: Ancient Chinese Astronomy ................18 Why the Emperor Executed Hsi and Ho ........................................18 Time, Space, Harmony..................................................................19 Babylon Revisited ........................................................................20 The Venus Tablet..........................................................................20 Draftsmen of the Constellations? ..................................................21 Egypt Looks ..................................................................................22 Celestial Pyramids ........................................................................22 The Universe-in-a-Box ..................................................................23 Stonehenge and the New World..................................................23 Grecian Formula ..........................................................................24 Anaximander Puts Earth in Space ................................................24 Anaximenes Says Stars Burn ........................................................25 Pythagoras Calls Earth a Globe ....................................................25 Anaxagoras Explains Eclipses ......................................................26 Aristarchus Sets the Sun in the Middle and Us in Motion ..............26 Eratosthenes Sizes Up the Earth ....................................................26 00 1981 FM 6/11/01 9:55 AM Page viii The Complete Idiot’s Guide to Astronomy, Second Edition 3 The Unexplained Motions of the Heavens 31 Time on Our Hands......................................................................32 What Really Happens in a Day? ..................................................32 A Month of Moons ......................................................................34 Another Wrinkle in Time ..............................................................37 To Everything a Season ................................................................38 The Sun Goes Dark, the Moon Becomes Blood ..........................41 Aristotle Lays Down the Law ......................................................41