Preface xi |
Preview |
The Cosmic Landscape 1 |
P.1 The Earth, Our Home 2 |
P.2 The Moon 3 |
P.3 The Planets 3 |
P.4 The Sun 4 |
P.5 The Solar System 5 |
P.6 A Sense of Scale 6 |
P.7 The Astronomical Unit 6 |
P.8 The Milky Way Galaxy 6 |
P.9 The Light-Year 8 |
P.10 Galaxy Clusters and the Universe 8 |
P.11 Gravity 9 |
P.12 Atoms and Other Forces 10 |
P.13 The Still Unknown Universe 10 |
P.14 The Scientific Method 11 |
Overview 1 The Night Sky 15 |
Chapter 1 |
History of Astronomy 23 |
1.1 Prehistoric Astronomy 24
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The Celestial Sphere 25
Constellations 25
Motions of the Sun and Stars 27
Daily or Diurnal Motion 27
Annual Motion 28
The Ecliptic 28
The Seasons 30
The Ecliptic's Tilt 31
Solstices and Equinoxes 32
The Planets and the Zodiac 34
The Moon 36
Eclipses 38
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1.2 Early Ideas of the Heavens:Classical Astronomy 39
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The Shape of the Earth 39
The Size of the Earth 40
Distance and Size of the Sun and Moon 41
Extending Our Reach: Measuring the Diameter of Astronomical Objects 42
The Motion of the Planets 45
Ptolemy 45
Islamic Contributions 46
Asian Contributions 46
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1.3 Astronomy in the Renaissance 46
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Copernicus 46
Tycho and Kepler 48
Galileo 51
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1.4 Isaac Newton and the Birth of Astrophysics 53 |
1.5 The Growth of Astrophysics 54
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New Discoveries 54
New Technologies 54
The Nature of Matter and Heat 54
The Kelvin Temperature Scale 55
Projects 58
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Essay 1 |
Backyard Astronomy 61
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Learning the Constellations 61
Star Lore 62
Amateur Astronomy 63
Small Telescopes 64
Star Charts 65
Celestial Coordinates 65
Planetary Configurations 67
Your Eyes at Night 69
Overview 2 Atoms, Forces, Light, and How We Learn about the Universe 71
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Chapter 2 |
Gravity and Motion 79 |
2.1 Solving the Problem of Astronomical Motion 80 |
2.2 Inertia 80 |
2.3 Orbital Motion and Gravity 82 |
2.4 Newton's Second Law of Motion 83
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2.5 The Law of Gravity 85 |
2.6 Newton's Third Law of Motion 85 |
2.7 Measuring a Body's Mass Using Orbital Motion 86 |
2.8 Surface Gravity 88 |
2.9 Escape Velocity 90 |
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Chapter 3 |
Light and Atoms 95 |
3.1 Properties of Light 96
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The Nature of Light--Waves or Particles? 96
Light and Color 97
Characterizing Electromagnetic Waves by Their Frequency 99
White Light 99
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3.2 The Electromagnetic Spectrum: Beyond Visible Light 100
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Infrared Radiation 101
Ultraviolet Light 101
Radio Waves 101
Other Wavelength Regions 101
Energy Carried by Electromagnetic Radiation 102
Wien's Law: A Wavelength-Temperature Relation 102
Extending Our Reach: Taking the Temperature of the Sun 103
Blackbodies and Wien's Law 104
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3.3 Atoms 104
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Structure of Atoms 105
The Chemical Elements 105
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3.4 The Origin of Light 106 |
3.5 Formation of a Spectrum 108
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How a Spectrum Is Formed 108
Identifying Atoms by Their Light 110
Types of Spectra 111
Depicting Spectra 112
Analyzing the Spectrum 112
Astronomical Spectra 113
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3.6 The Doppler Shift 114 |
3.7 Absorption in the Atmosphere 115 |
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Chapter 4 |
Telescopes 119 |
4.1 Telescopes 120
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Collecting Power 120
Focusing the Light 120
Extending Our Reach: Refraction 121
Resolving Power 127
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4.2 Interferometers 128 |
4.3 Observatories 130 |
4.4 Detecting the Light 131 |
4.5 Observing at Nonvisible Wavelengths 131
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Extending Our Reach: Exploring New Wavelengths: Gamma Rays 134
Extending Our Reach: Observing the Crab Nebula at Many Wavelengths 134
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4.6 Observatories in Space 136
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Atmospheric Blurring 137
Space Observatories versus Ground-Based Observatories 138
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4.7 Going Observing 140 |
4.8 Computers 141 |
4.9 Astronomers 142
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Projects 144
Overview 3 Stars 145
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Chapter 5 |
The Sun, Our Star 151 |
5.1 Size and Structure 152
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Measuring the Sun's Properties 153
The Solar Interior 154
Energy Transport 154
Convection in the Sun 155
The Solar Atmosphere 155
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5.2 How the Sun Works 157
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Internal Balance (Hydrostatic Equilibrium) 157
Pressure in the Sun 157
Powering the Sun 158
Nuclear Fusion 159
The Structure of Hydrogen and Helium 159
The Proton-Proton Chain 160
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5.3 Probing the Sun's Core 161
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Solar Neutrinos 161
Solar Seismology 162
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5.4 Solar Magnetic Activity 163
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Sunspots 164
Solar Magnetic Fields 164
Prominences and Flares 164
Heating of the Chromosphere and Corona 167
Extending Our Reach: Detecting Magnetic Fields: The Zeeman Effect 168
The Solar Wind 169
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5.5 Solar Cycle 169
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Cause of the Solar Cycle 169
Changes in the Solar Cycle 171
Links between the Solar Cycle and Terrestrial Climate 172
Projects 176
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Chapter 6 |
Measuring the Properties of Stars 177 |
6.1 Measuring a Star's Distance 178
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Measuring Distance by Triangulation and Parallax 178
Measuring Distance by the Standard-Candles Method 180
Extending Our Reach: Measuring the Distance to Sirius 181
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6.2 Measuring the Properties of Stars from Their Light 182
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Temperature 182
Luminosity 183
The Inverse-Square Law and Measuring a Star's Luminosity 183
Radius 184
The Stefan-Boltzmann Law 185
Extending Our Reach: Measuring the Radius of the Star Sirius 187
The Magnitude System 187
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6.3 Spectra of Stars 188
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Measuring a Star's Composition 189
How Temperature Affects a Star's Spectrum 190
Classification of Stellar Spectra 190
Re-Modeling: New Spectrum Classes 192
Definition of the Spectral Classes 192
Measuring a Star's Motion 193
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6.4 Binary Stars 195
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Visual and Spectroscopic Binaries 196
Measuring Stellar Masses with Binary Stars 197
Eclipsing Binary Stars 198
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6.5 Summary of Stellar Properties 199 |
6.6 The H-R Diagram 199
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Constructing the H-R Diagram 200
Analyzing the H-R Diagram 201
Giants and Dwarfs 202
The Mass-Luminosity Relation 202
Luminosity Classes 203
Summary of the H-R Diagram 204
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6.7 Variable Stars 204 |
6.8 Finding a Star's Distance by the Method of Standard Candles 206
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Chapter 7 |
Stellar Evolution 211 |
7.1 The Evolution of a Star 212
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The Sun's Life Story 213
The Life Story of a High-Mass Star 214
The Importance of Gravity 215
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7.2 Star Formation 216
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Interstellar Gas Clouds 216
Protostars 217
Bipolar Flows from Young Stars 217
Stellar Mass Limits 219
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7.3 Main-Sequence Stars 220
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Why a Star's Mass Determines Its Core Temperature 220
Structure of High-Mass and Low-Mass Stars 220
Main-Sequence Lifetime of a Star 221
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7.4 Giant Stars 222
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Leaving the Main Sequence 222
Nuclear Fuels Heavier Than Hydrogen 222
Degeneracy in Low-Mass Stars 223
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7.5 Yellow Giants and Pulsating Stars 224
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Why Do Stars Pulsate? 224
The Period-Luminosity Law 226
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7.6 Death of Stars Like the Sun 226
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Ejection of a Low-Mass Star's Outer Layers 226
Re-Modeling: Planetary Nebulas 227
Planetary Nebulas 227
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7.7 Old Age of Massive Stars 229
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Formation of Heavy Elements: Nucleosynthesis 230
Core Collapse of Massive Stars 230
Supernova Explosions 231
Supernova Remnants 231
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7.8 History of Stellar Evolution Theories 233 |
7.9 Testing Stellar Evolution Theory 234
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Extending Our Reach: Measuring the Age of a Star Cluster 235
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Chapter 8 |
Stellar Remnants: White Dwarfs, Neutron Stars, and Black Holes 241 |
8.1 White Dwarfs 242
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General Properties, Origin, and Fate 242
Structure of White Dwarfs 243
Degeneracy and the Chandrasekhar Limit 244
White Dwarfs in Binary Systems: Novas and Supernovas of Type I 245
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8.2 Neutron Stars 246
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General Properties and Origin 246
Pulsars and the Discovery of Neutron Stars 247
Emission from Neutron Stars 249
X-Ray Binary Stars 252
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8.3 Black Holes 253
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The Formation of Black Holes 255
Observing Black Holes 255
Gravitational Waves from Double Compact Stars 256
Hawking Radiation 257
Overview 4 The Milky Way and Other Galaxies 261
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Chapter 9 |
The Milky Way Galaxy 267 |
9.1 Discovering the Milky Way 269
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Shape of the Milky Way 269
Size of the Milky Way 270
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9.2 Overview of the Milky Way 272
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Structure and Contents 272
Mass of the Milky Way and the Number of Stars 273
Age of the Milky Way 274
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9.3 Stars of the Milky Way 274
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Stellar Censuses and the Mass Function 274
Two Stellar Populations: Population I and Population II 275
Star Clusters 277
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9.4 Gas and Dust in the Milky Way 279
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Interstellar Dust: Obscuration and Reddening 280
Interstellar Gas 282
Visible Emission from Interstellar Gas 282
Radio Waves from Cold Interstellar Gas 284
Extending Our Reach: Mapping the Milky Way with Radio Waves 284
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9.5 Motion of Stars and Gas in the Milky Way 285 |
9.6 Measuring the Milky Way 288
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Diameter of the Milky Way 288
Mass of the Milky Way 288
Extending Our Reach: Measuring the Mass of the Milky Way 289
Extending Our Reach: Measuring the Sun's Speed Around the Milky Way 291
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9.7 The Galactic Center 291 |
9.8 History of the Milky Way 293
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Formation of Our Galaxy 293
Collapse of the Proto-Milky Way and the Birth of Population I and II Stars 293
Population III 296
The Future of the Milky Way 296
Project 299
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Chapter 10 |
Galaxies 301 |
10.1 Discovering Galaxies 302
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Early Observations of Galaxies 302
Types of Galaxies 303
Differences in the Stellar and Gas Content of Galaxies 307
The Cause of Galaxy Types 309
Galaxy Collisions and Mergers 310
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10.2 Measuring Properties of Galaxies 312
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Galaxy Distances 312
Extending Our Reach: Measuring the Distance of a Galaxy Using Cepheid Variables 313
The Redshift and the Hubble Law 314
Measuring the Diameter of a Galaxy 315
Extending Our Reach: Other Ways to Measure a Galaxy's Distance 316
Measuring the Mass of a Galaxy 316
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10.3 Dark Matter 317 |
10.4 Active Galaxies 318
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Radio Galaxies 318
Seyfert Galaxies 320
Quasars 320
Cause of Activity in Galaxies 321
Extending Our Reach: Measuring the Diameter of Astronomical Objects by Using Their Light Variability 322
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10.5 Quasars As Probes of Intergalactic Space 324
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Gravitational Lenses 325
Extending Our Reach: Dark Matter and Gravitational Lenses 326
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10.6 Galaxy Clusters 326
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The Local Group 327
Rich and Poor Galaxy Clusters 328
Superclusters 329
Project 333
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Chapter 11 |
Cosmology 335 |
11.1 Observations of the Universe 336
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Distribution of Galaxies 336
Motion of Galaxies 337
Age of the Universe 338
Extending Our Reach: Estimating the Age of the Universe 338
Re-Modeling: Age Discrepancy 339
The Cosmic Horizon 340
The Size of the Universe 340
Are We at the Center of the Universe? 341
Olbers' Paradox 341
The Cosmic Microwave Background 343
Composition of the Oldest Stars 344
Conclusions Deduced from the Basic Observations of the Universe 345
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11.2 Evolution of the Universe: Open or Closed? 346
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The Density of the Universe 347
A Cosmological Repulsion? 348
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11.3 The Shape of the Universe 349 |
11.4 The Origin of the Universe 350
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Radiation, Matter, and Antimatter in the Early Universe 351
History of Matter and Radiation in the Early Universe 352
The Formation of Galaxies 353
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11.5 The Inflationary Universe 354
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Extending Our Imagination: Grand Unified Theories 355
Overview 5 The Earth and Moon 361
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Chapter 12 |
The Earth 367 |
12.1 The Earth As a Planet 368
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Shape and Size of the Earth 368
Composition of the Earth 370
Density of the Earth 370
Extending Our Reach: Measuring the Earth's Mass 371
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12.2 The Earth's Interior 371
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Probing the Interior with Earthquake Waves 371
Heating of the Earth's Core 374
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12.3 The Age of the Earth 376 |
12.4 Motions in the Earth's Interior 377
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Plate Tectonics 377
Extending Our Reach: Measuring the Motion of Plates across Time 380
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12.5 The Earth's Atmosphere 380
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Composition of the Atmosphere 381
Origin of the Atmosphere 381
The Ozone Layer 383
The Greenhouse Effect 384
Structure of the Atmosphere 384
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12.6 The Earth's Magnetic Field 385
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Origin of the Earth's Magnetic Field 386
Magnetic Effects in the Upper Atmosphere 386
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12.7 Motions of the Earth 388
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Air and Ocean Circulation: The Coriolis Effect 388
Precession 390
Project 393
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Essay 2 |
Keeping Time 395
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Length of the Daylight Hours 395
The Day 395
Time Zones 398
Universal Time 398
Daylight Saving Time 398
The Month 398
The Calendar 399
Leap Year 400
Religious Calendars 400
Other Calendars 400
Names of the Months and Days 400
The Abbreviations a.m., p.m., b.c., and a.d. 401
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Chapter 13 |
The Moon 403 |
13.1 Description of the Moon 404
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General Features 404
Surface Features 404
Origin of Lunar Surface Features 406
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13.2 Structure of the Moon 409
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Crust and Interior 409
The Absence of a Lunar Atmosphere 410
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13.3 Orbit and Motions of the Moon 411
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The Moon's Rotation 411
Oddities of the Moon's Orbit 412
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13.4 Origin and History of the Moon 413 |
13.5 Eclipses 315
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Rarity of Eclipses 416
Appearance of Eclipses 418
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13.6 Tides 420
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Cause of Tides 420
Solar Tides 422
Tidal Braking 423
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13.7 Moon Lore 424
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Project 427
Overview 6 The Solar System 429
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Chapter 14 |
Survey of the Solar System 437 |
14.1 Components of the Solar System 438
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The Sun 438
The Planets 439
Two Types of Planets 440
Satellites 441
Asteroids and Comets 442
Composition Differences between the Inner and Outer Planets 443
Density as a Measure of a Planet's Composition 443
Extending Our Reach: Bode's Law: The Search for Order 444
Age of the Solar System 445
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14.2 Origin of the Solar System 446
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Interstellar Clouds 447
Formation of the Solar Nebula 447
Condensation in the Solar Nebula 448
Accretion and Planetesimals 450
Formation of the Planets 450
Re-Modeling: Direct Formation of Giant Planets 451
Formation of Moons 452
Final Stages of Planet Formation 452
Formation of Atmospheres 452
Cleaning up the Solar System 452
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14.3 Other Planetary Systems 454
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Re-Modeling: Migrating Planets 455
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Chapter 15 |
The Terrestrial Planets 459 |
15.1 Portraits of the Terrestrial Planets 460 |
15.2 Mercury 462
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Mercury's Temperature and Atmosphere 463
Mercury's Interior 465
Mercury's Rotation 466
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15.3 Venus 467
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The Venusian Atmosphere 467
The Greenhouse Effect 468
The Surface of Venus 468
The Interior of Venus 472
Rotation of Venus 472
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15.4 Mars 473
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The Martian Atmosphere 476
The Martian Interior 479
The Martian Moons 480
Life on Mars? 480
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15.5 Why Are the Terrestrial Planets So Different? 481
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Role of Mass and Radius 481
Role of Internal Activity 482
Role of Sunlight 482
Role of Water Content 482
Role of Biological Processes 482
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15.6 Update: Exploring Mars 483 |
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Chapter 16 |
The Outer Planets 489 |
16.1 Jupiter 490
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Jupiter's Appearance and Physical Properties 490
Jupiter's Interior 491
Jupiter's Atmosphere 492
Jupiter's Ring 494
Jupiter's Moons 495
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16.2 Saturn 498
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Saturn's Appearance and Physical Properties 498
Saturn's Rings 499
Origin of Planetary Rings 501
The Roche Limit 501
Saturn's Moons 502
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16.3 Uranus 504
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Uranus's Atmosphere 504
Uranus's Interior 505
Uranus's Rings and Moons 506
Uranus's Odd Tilt 506
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16.4 Neptune 507
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Neptune's Structure 508
Neptune's Atmosphere 509
Neptune's Rings and Moons 510
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16.5 Pluto 511 |
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Chapter 17 |
Meteors, Asteroids, and Comets 517 |
17.1 Meteors and Meteorites 518
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Heating of Meteors 518
Meteorites 518
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17.2 Asteroids 520
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Size and Shape 520
Composition 522
Origin of Asteroids 522
Unusual Asteroids 523
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17.3 Comets 525
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Structure of Comets 525
Composition of Comets 527
Origin of Comets 527
Formation of the Comet's Tail 528
Light from the Comet's Tail 529
Short-Period Comets 530
Re-Modeling: The Kuiper Belt 531
Fate of Short-Period Comets 531
Meteor Showers 531
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17.4 Giant Impacts 533
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Giant Meteor Craters 533
Mass Extinction and Asteroid/Comet Impacts 534
Re-Modeling: Ghost Craters or No Tell-Tale Fragments 535
Re-Modeling: Meteorites Can Be Deadly 536
Projects 538
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Essay 3 |
Life in the Universe 539
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Life on Earth 539
History of Life on Earth 539
Unity of Living Beings 540
Deductions from the Unity of Life and the Time Line 542
Origin of Life on Earth 542
Origin of Complex Organisms 543
Panspermia 543
Life Elsewhere in the Universe 543
Are We Alone? 543
Arguments for Many Worlds 544
Loners 545
Searching for Life Elsewhere 545
Radio Searches 545
The Gaia Hypothesis 546
The Anthropic Principle 546
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Answers to Test Yourself 551 |
Appendix 553 |
Powers-of-Ten Notation 553
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Some Useful Formulas 553
Solving Distance, Velocity, Time (D, v, t) Problems 554
Table 1 -Physical and Astronomical Constants 554
Table 2 -Conversion between American and Metric Units 555
Table 3 -Physical Properties of the Planets 555
Table 4 -Orbital Properties of the Planets 555
Table 5 -Satellites of the Solar System 556
Table 6 Meteor Showers 557
Table 7 The Constellations 558
Table 8 The Brightest Stars 560
Table 9 The Nearest Stars 561
Table 10 -Properties of Main-Sequence Stars 561
Table 11 Periodic Table of Elements 563
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Glossary 565 |
Index 579 |