CONTENTS CHAPTER ONE 4 Going the Distance CHAPTER SIX 54 Planets around Other Stars CHAPTER TWO CHAPTER SEVEN 16 Beginning a Cosmic Exploration 68 The Energetic Universe CHAPTER THREE CHAPTER EIGHT 80 The Dark Universe 26 The Tools of Astronomy CHAPTER FOUR 36 Simulating the Universe CHAPTER NINE 88 Exploring the Future CHAPTER FIVE 44 The Universe s Beginning 100 Essential Facts 102 Glossary 104 Additional Resources 106 Source Notes 110 Index 112 About the Author
ONE GOING THE DISTANCE le live on a planet that along with seven other planets and countless smaller V bodies orbits the sun Our sun is one of approximately 200 billion stars in the Milky Way galaxy and most of those stars appear likely to host planets of their own Our galaxy is just one island of lights in the universe s vast sea of hundreds of billions of galaxies Each galaxy is made up of billions of individual stars Astronomy is the study of all the objects that make up the universe outside Earth from the planets and comets in our solar system to the many types of stars in galaxies that are sprinkled across the universe To learn about these celestial objects astronomers study them using telescopes and other scientific instruments Because current technology makes it impossible to leave the Milky Way the only images showing the whole galaxy at once are artists impressions
