CONTENTS INTRODUCTION CHAPTER 1 THE SUN THE CENTER OF THE SOLAR SYSTEM 10 CHAPTER 2 STRUCTURE AND ENERGY PRODUCTION OF THE SUN 22 CHAPTER 3 THE SUN s MAGNETIC FIELDS AND SOLAR ACTIVITY 35 CHAPTER 4 THE STARS THEIR PLACE IN THE SKY 43 CHAPTER 5 THE PROPERTIES OF STARS 59 CHAPTER 6 THE LIVES OF STARS 68 CHAPTER 1 GALAXIES 76 88 ConCLUSION GoSSARY FOR MORE INFORMATION BIBLIOGRAPHY 90 93 INDEX 94
MN winkle twinkle little star How I wonder what you are Readers of this book will wonder no more In these pages lies information on the prop erties and characteristics of stars including one star that is vital to life on Earth the Sun Topics include star composition brightness and configuration into constellations the layers of the Sun and its role as the center of the solar system and the shape of and energy emitted by large groups of stars known as galaxies The scientific exploration of these illuminated celestial bodies through the years is also covered Up above the world so high Like a diamond in the sky The common image of stars as tiny points of light softly twinkling in the night sky belies their truly awesome power Even their births are intense Stars are formed when gravity forces a cloud of dust and debris to contract causing a violent collision of hydrogen atoms This high level of intensity carries through the life of a star as its core or nucleus burns courtesy of continuous explosions that are
INTRODutrios like nuclear bombs detonating Eventually all the fuel in the core gets used up and many stars simply collapse in upon themselves This process leaves a small core that will eventually burn itself out as it cools Some stars however go out in spectacular fashion as supernovas exploding into vast fields of debris that even tually contribute to the creation of new stars In the vast scheme of the universe the Sun is a pretty average star It is estimated to be nearly 5 billion years old which means it still has billions of years to shine before it reaches the end of its life cycle Size wise the Sun falls somewhere in the middle between massive giants and tiny dwarfs Within the solar system however the Sun is anything but average Here it is the center of all the action A full 99 percent of the solar system s mass is taken up by the Sun Eight planets and their satellites the dwarf planets and an assortment of meteors asteroids and other celestial bodies account for the remaining 1 percent Although it is roughly the same size as billions of other stars the Sun appears larger because it is relatively close 93 million miles 150 million kilometers to Earth At the center of the Sun is the core an extremely dense pressure filled collection
