Understanding Our Universe

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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