Introduction 7 Chapter1 The Milky Way 10 Globular Clusters 11 Open Clusters 14 Stellar Associations 17 Moving Groups 19 Emission nebulae 20 Planetary Nebulae 21 Dust Clouds 23 The Interstellar Medium 26 Companions of the Milky Way Galaxy 28 Size of the Milky Way Galaxy 30 The Milky Way Galaxy Nucleus 31 Understanding Black Holes 33 The Central Bulge 33 The Disk 36 The Spiral Arms 37 The Spherical Component 39 CONTENTS
The Milky Way Galaxy’s Massive Halo 40 Magnetic Field 40 Rotation of the Milky Way Galaxy 41 The Galaxy’s Mass 43 Chapter2 The Study of Galaxies 47 Galaxy Evolution 49 Andromeda Nebula Novae 55 Van Maanen Rotation 56 Shapley-Curtis Debate 59 Hubble and the Discovery Of Extragalactic Objects 61 The Distance to the Andromeda Nebula 65 Edwin Powell Hubble 66 Extragalactic Astronomy 70 Chapter3 Galaxies of Many Types 72 Elliptical Galaxies 73 Spiral Galaxies 75 S0 Galaxies 77
Sa Galaxies 79 Sb Galaxies 79 Andromeda Galaxy 80 Sc Galaxies 82 SB Galaxies 83 Irregular Galaxies 85 Other Types of Galaxies 87 Chapter4 Galaxies Other Than Our Own 89 Luminosity of External Galaxies 90 Age 91 Composition of External Galaxies 92 Galaxy Clusters 95 Distribution of Clusters 97 How Cluster Members Interact 99 Radio Galaxies 101 Virgo A 104 X-ray Galaxies 105 Radio and X-ray Sources 106 Quasars 107
