Understanding Our Universe

Understanding Our Universe, 3e......Page 1
Title Page......Page 4
Copyright Information......Page 5
Dedication......Page 6
Brief Table of Contents......Page 8
Contents......Page 10
Astronomy in Action Videos......Page 17
Preface......Page 18
About the Authors......Page 29
1. Our Place in the Universe......Page 31
1.1 Astronomy Gives Us a Universal Context......Page 33
1.2 Science Is a Way of Viewing the World......Page 37
1.3 Astronomers Use Mathematics to Find Patterns......Page 40
Working It Out 1.1: Units and Scientific Notation......Page 43
Reading Astronomy News: “Breakthrough: Scientists Detect Einstein’s Gravity Ripples"......Page 45
Questions and Problems......Page 47
Exploration: Logical Fallacies......Page 50
2. Patterns in the Sky—Motions of Earth and the Moon......Page 51
2.1 Earth Spins on Its Axis......Page 53
2.2 Revolution Around the Sun Leads to Changes during the Year......Page 59
Working It Out 2.1: Manipulating Equations......Page 60
2.3 The Moon’s Appearance Changes as It Orbits Earth......Page 66
2.4 Shadows Cause Eclipses......Page 68
Reading Astronomy News: “Eclipse 2017: ‘I Need Like Two More Hours of That'"......Page 71
Questions and Problems......Page 73
Exploration: Phases of the Moon......Page 76
3. Laws of Motion......Page 77
3.1 Astronomers Have Studied the Motions of the Planets Since Ancient Times......Page 79
Working It Out 3.1: Kepler’s Third Law......Page 83
3.2 Galileo Was the First Modern Scientist......Page 84
3.3 Newton’s Laws Govern Motion......Page 85
Working It Out 3.2: Finding the Acceleration......Page 87
3.4 Gravity Is a Force between Any Two Massive Objects......Page 89
Working It Out 3.3: Newton’s Law of Gravity: Playing with Proportionality......Page 91
3.5 Orbits Are One Body “Falling Around” Another......Page 93
Reading Astronomy News: “Curiosity, Interrupted: Sun Makes Mars Go Dark"......Page 97
Questions and Problems......Page 99
Exploration: Newtonian Features......Page 102
4. Light and Telescopes......Page 103
4.1 What Is Light?......Page 105
Working It Out 4.1: Wavelength and Frequency......Page 108
4.2 Cameras and Spectrographs Record Astronomical Data......Page 112
4.3 Telescopes Collect Light......Page 115
Working It Out 4.2: Diffraction Limit......Page 120
Reading Astronomy News: “NASA’s James Webb Space Telescope Could Study Planet 9"......Page 122
Summary......Page 123
Questions and Problems......Page 124
Exploration: Light as a Wave......Page 126
5. The Formation of Stars and Planets......Page 127
5.1 Molecular Clouds Are the Cradles of Star Formation......Page 129
5.2 The Protostar Becomes a Star......Page 131
Working It Out 5.1: The Stefan-Boltzmann Law and Wien’s Law......Page 132
5.3 Planets Form in a Disk around the Protostar......Page 136
5.4 The Inner and Outer Disk Have Different Compositions......Page 142
5.5 A Case Study: The Solar System......Page 143
5.6 Planetary Systems Are Common......Page 146
Working It Out 5.2: Making Use of the Doppler Shift......Page 148
Reading Astronomy News: “Kepler Provides More Information About Trappist-1"......Page 152
Questions and Problems......Page 153
Exploration: Exploring Extrasolar Planets......Page 156
6. Terrestrial Worlds in the Inner Solar System......Page 157
6.1 Impacts Help Shape the Terrestrial Planets......Page 159
Working It Out 6.1: How to Read Cosmic Clocks......Page 164
6.2 The Surfaces of Terrestrial Planets Are Affected by Processes in the Interior......Page 165
Working It Out 6.2: The Density of Earth......Page 166
6.3 Planetary Surfaces Evolve through Tectonism......Page 171
6.4 Volcanism Reveals a Geologically Active Planet......Page 176
6.5 Wind and Water Modify Surfaces......Page 179
Reading Astronomy News: “Mars Canyon Study Adds Clues About Possible Water"......Page 183
Questions and Problems......Page 185
Exploration: Earth’s Tides......Page 188
7. Atmospheres of Venus, Earth, and Mars......Page 189
7.1 Atmospheres Change over Time......Page 191
7.2 Secondary Atmospheres Evolve......Page 193
Working It Out 7.1: How Can We Find the Temperature of a Planet?......Page 195
7.3 Earth’s Atmosphere Has Detailed Structure......Page 198
7.4 The Atmospheres of Venus and Mars Differ from Earth’s......Page 205
7.5 Earth’s Climate Is Changing......Page 208
Reading Astronomy News: “Curiosity Rover Sees Signs of Vanishing Martian Atmosphere"......Page 212
Questions and Problems......Page 213
Exploration: Climate Change......Page 216
8. The Giant Planets......Page 217
8.1 Giant Planets Are Large, Cold, and Massive......Page 219
Working It Out 8.1: Finding the Diameter of a Giant Planet......Page 222
8.2 The Giant Planets Have Clouds and Weather......Page 224
Working It Out 8.2: Measuring Wind Speeds On Distant Planets......Page 229
8.3 The Interiors of the Giant Planets Are Hot and Dense......Page 231
Working It Out 8.3: Internal Thermal Energy Heats the Giant Planets......Page 233
8.4 The Giant Planets Are Magnetic Powerhouses......Page 234
8.5 Rings Surround the Giant Planets......Page 237
Reading Astronomy News: “Giant Propeller Structures Seen In Saturn’s Rings"......Page 241
Questions and Problems......Page 243
Exploration: Estimating Rotation Periods of Giant Planets......Page 246
9. Small Bodies of the Solar System......Page 247
9.1 Dwarf Planets May Outnumber Planets......Page 249
9.2 Moons as Small Worlds......Page 251
9.3 Asteroids Are Pieces of the Past......Page 258
9.4 Comets Are Clumps of Ice......Page 261
9.5 Comet and Asteroid Collisions Still Happen Today......Page 267
Working It Out 9.1: Finding the Radius of a Meteoroid......Page 269
9.6 Meteorites Are Remnants of the Early Solar System......Page 270
Reading Astronomy News: “The Rosetta Probe Has Officially Stopped Listening for Philae, Its Little Lost Comet Lander"......Page 274
Questions and Problems......Page 275
Exploration: Comparative Dwarf Planetology......Page 278
10. Measuring the Stars......Page 279
10.1 The Luminosity of a Star Can Be Found from the Brightness and the Distance......Page 281
Working It Out 10.1: Parallax and Distance......Page 285
10.2 Radiation Tells Us the Temperature, Size, and Composition of Stars......Page 287
10.3 The Mass of a Star Can Be Determined in Some Binary Systems......Page 297
10.4 The H-R Diagram Is the Key to Understanding Stars......Page 300
Reading Astronomy News: “Mystery of Nearby SS Cygni Star System Finally Resolved"......Page 304
Questions And Problems......Page 305
Exploration: The H-R Diagram......Page 308
11. Our Star: The Sun......Page 309
11.1 The Structure of the Sun Is a Matter of Balance......Page 311
Working It Out 11.1: How Much Longer Will the Sun “Live"?......Page 313
11.2 Energy in the Sun’s Core Moves through Radiation and Convection......Page 316
11.3 The Atmosphere of the Sun......Page 320
11.4 The Atmosphere of the Sun Is Very Active......Page 323
Working It Out 11.2: Sunspots and Temperature......Page 325
Reading Astronomy News: “Weather Forecast in Space: Not Sunny, with Solar Flares"......Page 331
Summary......Page 332
Questions and Problems......Page 333
Exploration: The Proton-Proton Chain......Page 336
12. Evolution of Low-Mass Stars......Page 337
12.1 The Life of a Main-Sequence Star Follows a Predictable Path......Page 339
Working It Out 12.1: Estimating Main-Sequence Lifetimes......Page 341
12.2 A Star Runs Out of Hydrogen and Leaves the Main Sequence......Page 342
12.3 Helium Begins to Burn in the Degenerate Core......Page 345
12.4 The Low-Mass Star Enters the Last Stages of Its Evolution......Page 348
12.5 Binary Stars Sometimes Share Mass, Resulting in Novae and Supernovae......Page 354
12.6 Star Clusters Are Snapshots of Stellar Evolution......Page 357
Reading Astronomy News: “Scientists May Be Missing Many Star Explosions"......Page 360
Questions and Problems......Page 361
Exploration: Evolution of Low-Mass Stars......Page 364
13. Evolution of High-Mass Stars......Page 365
13.1 High-Mass Stars Follow Their Own Path......Page 367
13.2 High-Mass Stars Go Out with a Bang......Page 371
13.3 Supernovae Change the Galaxy......Page 374
13.4 Einstein Moved Beyond Newtonian Physics......Page 379
Working It Out 13.1: The Boxcar Experiment......Page 382
13.5 Gravity Is a Distortion of Spacetime......Page 384
13.6 Black Holes Are a Natural Limit......Page 390
Working It Out 13.2: Finding the Schwarzschild Radius......Page 391
Reading Astronomy News: “LIGO Is Back and It’s on the Hunt for Gravitational Waves Again"......Page 394
Questions and Problems......Page 395
Exploration: The CNO Cycle......Page 398
14. Measuring Galaxies......Page 399
14.1 Galaxies Come in Many Sizes and Shapes......Page 401
14.2 There Are Many Ways to Measure Distance......Page 406
14.3 We Live in an Expanding Universe......Page 410
Working It Out 14.1: Redshift: Calculating the Recession Velocities and Distances of Galaxies......Page 412
14.4 A Supermassive Black Hole Exists at the Heart of Most Galaxies......Page 413
Reading Astronomy News: “Colliding Galaxies Swirl in Dazzling New Photo"......Page 420
Summary......Page 421
Questions and Problems......Page 422
Exploration: Galaxy Classification......Page 424
15. Our Galaxy: The Milky Way......Page 425
15.1 Galaxies Are Mostly Dark Matter......Page 427
Working It Out 15.1: Finding the Mass of a Galaxy......Page 431
15.2 Stars Form in the Spiral Arms of a Galaxy’s Disk......Page 433
15.3 Components of the Milky Way Reveal Its Evolution......Page 437
15.4 The Milky Way Offers Clues about How Galaxies Form......Page 443
Reading Astronomy News: “Hyperfast Star Kicked Out of Milky Way"......Page 445
Questions and Problems......Page 447
Exploration: Dark Matter in a Galaxy......Page 450
16. The Evolution of the Universe......Page 451
16.1 Hubble’s Law Implies a Hot, Dense Beginning......Page 453
Working It Out 16.1: Expansion and the Age of the Universe......Page 454
16.2 The Cosmic Microwave Background Confirms the Big Bang......Page 457
16.3 The Expansion of the Universe Is Speeding Up......Page 461
16.4 The Earliest Moments of the Universe Connect the Very Largest Size Scales to the Very Smallest......Page 464
16.5 Inflation Solves Several Problems in Cosmology......Page 469
16.6 Other Universes?......Page 471
Reading Astronomy News: “Gravity May Have Chased Light in the Early Universe"......Page 473
Questions and Problems......Page 474
Exploration: Hubble’s Law for Balloons......Page 477
17. Formation of Structure......Page 479
17.1 Galaxies Form Groups, Clusters, and Larger Structures......Page 481
17.2 Gravity Forms Large-Scale Structure......Page 484
17.3 The First Stars and Galaxies Form......Page 489
17.4 Galaxies Evolve......Page 492
17.5 Astronomers Think about the Far Future......Page 496
Reading Astronomy News: “Massive Black Holes Sidle Up to Other Galaxies"......Page 498
Questions and Problems......Page 499
Exploration: The Story of a Proton......Page 502
18. Life in the Universe......Page 503
18.1 Life on Earth Began Early and Evolved over Time......Page 505
Working It Out 18.1: Exponential Growth......Page 511
18.2 Life beyond Earth Is Possible......Page 512
18.3 Scientists Search for Signs of Intelligent Life......Page 519
18.4 The Fate of Life on Earth......Page 523
Reading Astronomy News: “Scientists Find Signs That Saturn’s Moon Enceladus Might Be Hospitable to Life"......Page 525
Questions and Problems......Page 527
Exploration: Fermi Problems and the Drake Equation......Page 530
Appendix 1. Periodic Table of the Elements......Page 532
Appendix 2. Properties of Planets, Dwarf Planets, and Moons......Page 533
Appendix 3. Nearest and Brightest Stars......Page 536
Appendix 4. Star Maps......Page 538
Glossary......Page 544
Selected Answers......Page 560
Credits......Page 564
Index......Page 566