• The Dark Age when the big bang had Imagine the history of the universe cooled and before as a time line down the middle of a stars began to shine football field. The story begins on one goal line as the big bang fills Formation of the the universe with energy and a first galaxies fantastically hot gas of hydrogen well under way and helium. Follow the history The Age of Quasars: Galaxies, from the first inch of the time including our home galaxy, actively line as the expansion of the forming, colliding, and merging universe cools the gas and it begins to form galaxies and stars. The expansion of the universe stops slowing and begins accelerating. Recombination: A few hundred thousand years after the big bang, the gas becomes transparent to light. i r A typical galaxy contains 100 billion stars. Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. 59733_00a_IFC.indd 2 11/21/08 5:17:45 PM e F T h Goal line One-inch line c h I n s t s The sun is just a star. a Nuclear reactions First hominids make energy. • • Earth Moon (not to scale) Ten thousand years ago, on the 0.0026 inch line, humans begin building cities and modern civilization begins. Formation of the sun and planets from a cloud of interstellar gas and dust Life begins in Earth’s oceans. Cambrian explosion 540 million years ago: Life in Earth’s oceans becomes complex. Life first emerges onto the land. Over billions of years, generation Age of Dinosaurs after generation of stars have lived and died, cooking the hydrogen and helium of the big bang into the atoms of which you are made. Study the last inch of the time line to see the rise of human ancestors and the origin of civilization. Only in the last flicker of a moment on the time line have astronomers begun to understand the story. I t h c n One-inch line Goal line h T e L A bout the Authors Mike Seeds has been a Professor of Physics and Astronomy at Franklin and Mar- shall College in Lancaster, Pennsylvania, since 1970. In 1989 he received F&M Col- lege’s Lindback Award for Distinguished Teaching. Mike’s love for the history of as- tronomy led him to create upper-level courses on “Archaeoastronomy” and “Changing Concepts of the Universe.” His research interests focus on variable stars and the automation of astronomical telescopes. Mike is the author of Horizons: Exploring the Universe, Eleventh Edition (2010); Astronomy: The Solar System and Beyond, Sixth Edition (2010); Foundations of Astronomy, Tenth Edition (2008); and Perspectives on Astronomy (2008), all published by Brooks/Cole. He was Senior Consultant for creation of the 20-episode telecourse accompanying his book Horizons: Exploring the Universe. Dana Backman taught in the physics and astronomy department at Franklin and Marshall College in Lancaster,0 Pennsylvania, from 1991 until 2003. He invented and taught a course titled “Life in the Universe” in F&M’s interdisciplinary Founda- tions program. Dana now teaches introductory astronomy, astrobiology, and cos- mology courses in Stanford University’s Continuing Studies Program. His research interests focus on infrared observations of planet formation, models of debris disks around nearby stars, and evolution of the solar system’s Kuiper Belt. Dana is the author of the fi rst edition of Perspectives on Astronomy (2008); Horizons: Exploring the Universe, Eleventh Edition (2010); and Astronomy: The Solar System and Be- yond, Sixth Edition (2010), all published by Brooks/Cole. He is with the SETI Insti- tute in Mountain View, California, in charge of the education and public outreach program for SOFIA (Stratospheric Observatory for Infrared Astronomy) at NASA’s Ames Research Center. S I X T H E D I T I O N 6 Michael A. Seeds Joseph R. Grundy Observatory Franklin and Marshall College Dana E. Backman Stratospheric Observatory for Infrared Astronomy (SOFIA) SETI Institute Australia • Brazil • Japan • Korea • Mexico • Singapore • Spain • United Kingdom • United States Astronomy: The Solar System and Beyond, © 2010, 2008 Brooks/Cole, Cengage Learning Sixth Edition ALL RIGHTS RESERVED. No part of this work covered by the copyright Michael A. Seeds, Dana E. Backman herein may be reproduced, transmitted, stored, or used in any form Astronomy Editor: Kilian Kennedy or by any means, graphic, electronic, or mechanical, including but not limited to photocopying, recording, scanning, digitizing, taping, Web Publisher: Mary Finch distribution, information networks, or information storage and retrieval Development Editor: Teri Hyde systems, except as permitted under Section 107 or 108 of the 1976 Editorial Assistant: Joshua Duncan United States Copyright Act, without the prior written permission of the publisher. Media Editor: Rebecca Berardy Schwartz Marketing Manager: Nicole Mollica For product information and technology assistance, contact us at Marketing Assistant: Elizabeth Wong Cengage Learning Customer & Sales Support, 1-800-354-9706. Marketing Communications Manager: For permission to use material from this text or product, Belinda Krohmer submit all requests online at cengage.com/permissions. Further permissions questions can be e-mailed to Project Manager, Editorial Production: For Janet and Jamie This page intentionally left blank Part 1: The Sky CHAPTER 1 HERE AND NOW 1 CHAPTER 2 THE SKY 10 CHAPTER 3 CYCLES OF THE SKY 21 CHAPTER 4 THE ORIGIN OF MODERN ASTRONOMY 42 CHAPTER 5 LIGHT AND TELESCOPES 69 CHAPTER 6 ATOMS AND STARLIGHT 94 Part 2: The Solar System CHAPTER 7 THE SOLAR SYSTEM: AN OVERVIEW 108 CHAPTER 8 THE TERRESTRIAL PLANETS 131 CHAPTER 9 THE JOVIAN PLANETS, PLUTO, AND THE KUIPER BELT 166 CHAPTER 10 METEORITES, ASTEROIDS, AND COMETS 195 Part 3: The Stars CHAPTER 11 THE SUN 214 CHAPTER 12 THE FAMILY OF STARS 236 CHAPTER 13 THE FORMATION AND STRUCTURE OF STARS 266 CHAPTER 14 THE DEATHS OF STARS 292 CHAPTER 15 NEUTRON STARS AND BLACK HOLES 318 Part 4: The Universe of Galaxies CHAPTER 16 THE MILKY WAY GALAXY 341 CHAPTER 17 GALAXIES 367 CHAPTER 18 ACTIVE GALAXIES AND SUPERMASSIVE BLACK HOLES 390 CHAPTER 19 MODERN COSMOLOGY 403 Part 5: Life CHAPTER 20 LIFE ON OTHER WORLDS 428 Part 1: The Sky Chapter 1 | Here and Now 1 1-1 WHERE ARE WE? 2 1-2 WHEN IS NOW? 6 Reasoning with Numbers 1-3 WHY STUDY ASTRONOMY? 7 2-1 Magnitudes 15 Chapter 2 | The Sky 10 3-1 The Small-Angle Formula 34 2-1 THE STARS 11 4-1 Circular Velocity 61 2-2 THE SKY AND ITS MOTION 14 5-1 The Powers of a Telescope 77 6-1 Blackbody Radiation 100 Chapter 3 | Cycles of the Sky 21 6-2 The Doppler Formula 105 3-1 CYCLES OF THE SUN 22 3-2 ASTRONOMICAL INFLUENCES ON EARTH’S CLIMATE 26 3-3 THE CYCLES OF THE MOON 29 How Do We Know? Chapter 4 | The Origin of Modern Astronomy 42 4-1 CLASSICAL ASTRONOMY 43 1-1 The So-Called Scientifi c Method 7 4-2 COPERNICUS 46 2-1 Scientifi c Models 18 4-3 PLANETARY MOTION 49 3-1 Pseudoscience 26 4-4 GALILEO GALILEI 55 3-2 Evidence as the Foundation of Science 28 4-5 ISAAC NEWTON AND ORBITAL MOTION 58 3-3 Scientifi c Arguments 29 Chapter 5 | Light and Telescopes 69 4-1 Scientifi c Revolutions 49 5-1 RADIATION: INFORMATION FROM SPACE 70 4-2 Hypothesis, Theory, and Law 53 5-2 OPTICAL TELESCOPES 72 4-3 Cause and Effect 60 5-3 SPECIAL INSTRUMENTS 84 4-4 Testing a Theory by Prediction 65 5-4 RADIO TELESCOPES 86 5-1 Resolution and Precision 76 5-5 ASTRONOMY FROM SPACE 89 6-1 Quantum Mechanics 97 Chapter 6 | Atoms and Starlight 94 6-1 ATOMS 95 6-2 THE INTERACTION OF LIGHT AND MATTER 97 Concept Art Portfolios 6-3 INFORMATION FROM SPECTRA 101 The Sky Around You 16–17 The Cycle of the Seasons 24–25 The Phases of the Moon 32–33 The Ancient Universe 44–45 Orbiting Earth 62–63 Modern Astronomical Telescopes 80–81 Atomic Spectra 102–103