TABLE OF CONTENT S What is Astronomy 4 Key Events in the Early History of Astronomy 6 Views of the Universe 8 How People Used the Skies 9 The Solar System 12 The Origins of Our Solar System 15 The Sun 16 Mercury 18 Venus 20 Earth 22 Earth’s Moon 24 Mars 25 Jupiter 28 Saturn 31 Uranus 34 Neptune 36 The Dwarf Planets Pluto Ceres and Eris 38 Asteroids Meteoroids and Comets 40 Stars 42 What is a Star 42 Types of Stars 44 The Life Cycle of a Star 46 Galaxies 48 Types of Galaxies 48 The Milky Way 49 Other Galaxies 50 The Universe 52 Origins of the Universe 53 Possible Ends of the Universe 55 Space Exploration 57 Telescopes 57 Space Probes 58 Humans in Space 60 A History of Manned Spaceflight 61 A History of the United States Space Shuttle Program 61 People Who Study Space 62
4 W H A T I S A S T R O N O M Y ASTRONOMY SPACE What Is Astronomy Have you ever wondered what exists beyond our planet Or looked up in the night sky and wondered what it would be like to live on another planet in our solar system Do people or other beings live there already Astronomy is the study of the universe or outer space and can help you find the answers to all these questions and more Sun
5 W H A T I S A S T R O N O M Y ASTRONOMY SPACE Astronomers study all of the objects in the sky outside Earth’s atmosphere Some of the things they study are the sun moons stars planets galaxies asteroids and comets New technologies such as the Hubble Space Telescope help astronomers make new discoveries about outer space The science of astronomy is very old Throughout Earth’s history people have been curious about what they saw in the sky Different ideas developed about how the universe worked A star photographed by the Hubble Space Telescope Dust particles can be seen swirling around the star This drawing shows an 1848 telescope
ASTRONOMY SPACE Key Events in the Early History of Astronomy letters to stars still in use today work Mathematike Syntaxis Nasir al-Din al-Tusi first estimation of Earth-sun distance over 850 of the brightest stars The Julian calendar a purely solar calendar is introduced to the Roman Empire 280 B C Aristarchus thinks the Earth revolves around the sun He provides the 130 B C Hipparchus develops the first accurate star map and star catalogue with 45 B C 140 A D Ptolemy suggests the geocentric theory of the universe in his famous 1259 A D An observatory was built for the famous Persian astronomer 1543 A D Copernicus publishes his heliocentric theory of the universe 1582 A D Pope Gregory XIII introduces the Gregorian calendar 1603 A D Johann Bayer introduces his Bayer designation of stars assigning Greek 1608 A D Hans Lippershey a Dutch spectacles maker invents the telescope 1656 A D Christian Huygens discovers Saturn’s rings and Titan the fourth satellite 1659 A D Huygens notes markings on Mars 1666 A D Martian polar ice caps are noted by Cassini 1668 A D The first reflecting telescope was built by Newton 1675 A D While in Paris Danish astronomer Ole Romer measures the speed 1675 A D Cassini discovers that Saturn’s rings are split into two parts the gap is 1687 A D Newton publishes his theory of gravity This is viewed as the start of 1705 A D England Halley correctly predicts the return of a comet Halley’s comet 1758 A D Johann Palitzsch observes Halley’s comet as predicted by Halley in 1705 1781 A D Herschel discovers the planet Uranus 1781 A D Messier discovers galaxies nebula and star clusters while looking 1801 A D Piazzi discovers the first asteroid Ceres 1840 A D J W Draper takes first pictures of the moon 1846 A D Johann Galle observes and discovers Neptune 1877 A D Asaph Hall discovers Phobos and Deimos the moons of Mars 1877 A D Schiaparelli observes the canals on Mars 1878 A D The Great Red Spot on Jupiter becomes prominent 1905 A D Albert Einstein introduces his special Theory of Relativity 1916 A D Albert Einstein introduces his general Theory of Relativity 1923 A D Hubble shows that galaxies exist outside the Milky Way galaxy 1930 A D Clyde Tombaugh discovers Pluto 1931 A D Karl Jansky discovers cosmic radio waves 1937 A D The first radio telescope is built by Grote Reber Modern Astronomy in 1758 called the Cassini Division of Saturn of light for comets Y M O N O R T S A S I T A H W 6
