Astronomy For Dummies

Stephen P. Maran, PhD, is former Assistant Director of Space Sciences for Information and Outreach at NASA’s Goddard Space Flight Center. Richard Tresch Fienberg, PhD, is former Editor in Chief of Sky & Telescope magazine. Both Steve and Rick have received NASA medals for exceptional achievement.

Introduction 1

About This Book 2

Foolish Assumptions 2

Icons Used in This Book 3

Beyond the Book 3

Where to Go from Here 4

Part 1: Getting Started with Astronomy 5

Chapter 1: Seeing the Light: The Art and Science of Astronomy 7

Astronomy: The Science of Observation 8

What You See: The Language of Light 10

They wondered as they wandered: Understanding planets versus stars 10

If you see a Great Bear, start worrying: Naming stars and constellations 12

The smaller, the brighter: Getting to the root of magnitudes 19

What do I spy? Spotting the Messier Catalog and other sky objects 20

Looking back on light-years 22

Keep on moving: Figuring the positions of the stars 23

Gravity: A Force to Be Reckoned With 26

Space: A Commotion of Motion 27

Chapter 2: Join the Crowd: Skywatching Activities and Resources 29

You’re Not Alone: Astronomy Clubs, Websites, Smartphone Apps, and More 30

Joining an astronomy club for star-studded company 30

Checking websites, magazines, software, and apps 31

Visiting Observatories and Planetariums 35

Ogling the observatories 35

Popping in on planetariums 39

Vacationing with the Stars: Star Parties, Eclipse Trips, Dark Sky Parks, and More 39

Party on! Attending star parties 40

Getting festive at an astro fest 42

Tapping into Astronomy on Tap 42

To the path of totality: Taking eclipse cruises and tours 42

Motoring to telescope motels 44

Chapter 3: Terrific Tools for Observing the Skies 47

Seeing Stars: A Sky Geography Primer 48

As Earth turns 48

keep an eye on the North Star 51

Beginning with Naked-Eye Observations 53

Using Binoculars or a Telescope for a Better View 56

Binoculars: Sweeping the night sky 56

Telescopes: When closeness counts 60

Planning Your First Steps into Astronomy 70

Chapter 4: Just Passing Through: Meteors, Comets, and Artificial Satellites 73

Meteors: Wishing on a Shooting Star 74

Spotting sporadic meteors, fireballs, and bolides 75

Watching meteor showers: No umbrella needed 77

Comets: Dirty Ice Balls or Icy Dirt Balls? 81

Making heads and tails of a comet’s structure 82

Waiting for the “comets of the century” 86

Hunting for the next great comet 87

Artificial Satellites: Enduring a Love–Hate Relationship 90

Skywatching for artificial satellites 91

Finding satellite viewing predictions 92

UFOs: Could some be aliens? 94

Part 2: Going Once Around the Solar System 95

Chapter 5: A Matched Pair: Earth and Its Moon 97

Putting Earth under the Astronomical Microscope 98

One of a kind: Earth’s unique characteristics 98

Spheres of influence: Earth’s distinct regions 100

Examining Earth’s Time, Seasons, and Age 102

Orbiting for all time 102

Tilting toward the seasons 104

Estimating Earth’s age 106

Making Sense of the Moon 107

Get ready to howl: Identifying phases of the Moon 108

In the shadows: Watching lunar eclipses 110

Cultivating an interest in the occult(ations) 112

Hard rock: Surveying lunar geology 113

Quite an impact: Considering a theory about the Moon’s origin 119

Chapter 6: Earth’s Near Neighbors: Mercury, Venus, and Mars 121

Mercury: Weird, Hot, and Mostly Metal 122

Dry, Acidic, and Hilly: Piercing the Veil of Venus 123

Dropping the ball: Probing Venus with DAVINCI+ and EnVision 125

Something in the air: Life in Venus’s clouds? 125

Red, Cold, and Barren: Uncovering the Mysteries of Mars 125

Where have almost all the air and water gone? (Long time passing) 126

Does Mars support life? 128

Differentiating Earth through Comparative Planetology 131

Observing the Terrestrial Planets with Ease 132

Understanding elongation, opposition, and conjunction 133

Viewing Venus and its phases 135

Watching Mars as it loops around 137

Outdoing Copernicus by observing Mercury 139

Chapter 7: Rock On: The Asteroid Belt and Near-Earth Objects 141

Taking a Brief Tour of the Asteroid Belt 141

Getting the Dirt on (and off) Asteroids 145

Understanding the Threat That Near-Earth Objects Pose 146

When push comes to shove: Nudging an asteroid 148

Forewarned is forearmed: Surveying NEAs to protect Earth 149

Searching for Small Points of Light 150

Helping to track an occultation 151

Timing an asteroidal occultation 152

Chapter 8: Great Balls of Gas: Jupiter and Saturn 153

The Pressure’s On: Journeying Inside Jupiter and Saturn 153

Almost a Star: Gazing at Jupiter 154

Scanning for the Great Red Spot 156

Shooting for Galileo’s moons 157

Our Main Planetary Attraction: Setting Your Sights on Saturn 161

Ringing around the planet 162

Storm chasing across Saturn 164

Monitoring a moon of major proportions 164

Venting about geysers on Enceladus 166

Chapter 9: Far Out! Uranus, Neptune, Pluto, and Beyond 169

Breaking the Ice with Uranus and Neptune 169

Bull’s-eye! Tilted Uranus and its features 170

Against the grain: Neptune and its biggest moon 171

Meeting Pluto, the Amazing Dwarf Planet 173

Defining Pluto the geophysical way 174

Getting to the heart of Pluto 174

Looking at Pluto’s makeup 177

The moon chip doesn’t float far from the planet 177

Buckling Down to the Kuiper Belt 178

Viewing the Outer Planets 180

Sighting Uranus 180

Distinguishing Neptune from a star 180

Straining to see Pluto 181

Hunting New Planet Number Nine 182

Part 3: Starting with Old Sol: Meeting Stars And Galaxies 185

Chapter 10: The Sun: Star of Earth 187

Surveying the Sunscape 188

The Sun’s size and shape: A great bundle of gas 189

The Sun’s regions: Caught between the core and the corona 189

Solar activity: What’s going on out there? 192

Solar wind: Playing with magnets 196

Solar CSI: The mystery of the missing solar neutrinos 197

Four billion and counting: The life expectancy of the Sun 198

Don’t Make a Blinding Mistake: Safe Techniques for Solar Viewing 199

Viewing the Sun by projection 199

Viewing the Sun through front-end filters 204

Fun with the Sun: Solar Observation 206

Tracking sunspots 206

Experiencing solar eclipses 208

Surfing solar observatories 212

Chapter 11: Taking a Trip to the Stars 215

Life Cycles of the Hot and Massive 216

Young stellar objects: Taking baby steps 217

Main sequence stars: Enjoying a long adulthood 218

Red giants and supergiants: Big and bigger 219

Closing time: Coming up on the tail end of stellar evolution 220

Star Color, Brightness, and Mass 226

Spectral types: What color is my star? 227

Star light, star bright: Luminosity classifications 228

The brighter they burn, the bigger they swell: Mass determines class 229

Making sense of the H-R diagram 230

Eternal Partners: Binary and Multiple Stars 232

Binary stars and the Doppler effect 232

Two stars are binary, but three’s a crowd: Multiple stars 234

Change Is Good: Variable Stars 235

Go the distance: Pulsating stars 236

Explosive neighbors: Flare stars 238

Nice to nova: Exploding stars 238

Stellar hide-and-seek: Eclipsing binary stars 241

Hog the starlight: Microlensing events 242

Your Stellar Neighbors 242

How to Help Scientists by Observing the Stars 245

Chapter 12: Galaxies: The Milky Way and Beyond 247

Unwrapping the Milky Way 248

How and when did the Milky Way form? 249

What shape is the Milky Way? 249

Where can you find the Milky Way? 251

Star Clusters: Meeting Galactic Associates 252

A loose fit: Open clusters 253

A tight squeeze: Globular clusters 255

Fun while it lasted: OB associations 256

Taking a Shine to Nebulas 257

Picking out planetary nebulas 259

Breezing through supernova remnants 261

Enjoying Earth’s best nebular views 261

Getting a Grip on Galaxies 264

Surveying spiral, barred spiral, and lenticular galaxies 265

Examining elliptical galaxies 266

Looking at irregular, dwarf, and low surface brightness galaxies 267

Gawking at great galaxies 268

Discovering the Local Group of galaxies 271

Checking out clusters of galaxies 272

Sizing up superclusters, cosmic voids, and great walls 272

Chapter 13: Falling for Black Holes and Quasars 275

Black Holes: Keeping Your Distance 275

Looking over the black hole roster 276

Poking around the black hole interior 277

Surveying a black hole’s surroundings 280

Warping space and time 281

Detecting black hole collisions 283

Watching stars get swallowed by black holes 284

Quasars: Defying Definitions 285

Measuring the size of a quasar 286

Getting up to speed on jets 287

Exploring quasar spectra 287

Active Galactic Nuclei: Welcome to the Quasar Family 288

Sifting through different types of AGN 288

Examining the power behind AGN 290

Questioning what ORCs are 291

Part 4: Pondering the Remarkable Universe 293

Chapter 14: Planets of Other Suns: Is Anybody Out There? 295

Discovering Alien Worlds 296

Changing ideas on exoplanets 296

Finding exoplanets 298

Meeting the (exo)planets 302

Catching Proxima fever: Focusing on red dwarfs 305

Finding Earth-class planets orbiting TRAPPIST-1 307

Checking out planets for fun and science 308

Astrobiology: How’s Life on Other Worlds? 309

Extremophiles: Living the hard way 309

Seeking life in the solar system 310

Using Drake’s Equation to Discuss SETI 313

SETI Projects: Listening for E.T. 316

The flight of Project Phoenix 317

Space scanning with other SETI projects 318

Hot targets for SETI 320

SETI@home 321

Chapter 15: Delving into Dark Matter and Antimatter 323

Dark Matter: Understanding the Universal Glue 323

Gathering the evidence for dark matter 324

Debating the makeup of dark matter 328

Taking a Shot in the Dark: Searching for Dark Matter 329

Looking for WIMPs and other microscopic dark matter 329

MACHOs: Making a brighter image 331

Mapping dark matter with gravitational lensing 331

Dueling Antimatter: Proving That Opposites Attract 333

Chapter 16: The Big Bang and the Evolution of the Universe 335

Evidence for the Big Bang 336

Inflation: A Swell Time in the Universe 337

Something from nothing: Inflation and the vacuum 339

Falling flat: Inflation and the shape of the universe 339

Dark Energy: The Universal Accelerator 340

Universal Info Pulled from the Cosmic Microwave Background 341

Finding the lumps in the cosmic microwave background 342

Mapping the universe with the cosmic microwave background 342

In a Galaxy Far Away: Standard Candles and the Hubble Constant 344

Standard candles: How do scientists measure galaxy distances? 344

The Hubble constant: How fast do galaxies really move? 345

The Fate of the Universe 346

Part 5: the Part of Tens 347

Chapter 17: Ten Strange Facts about Astronomy and Space 349

You Have Tiny Meteorites in Your Hair 349

A Comet’s Tail Often Leads the Way 350

Earth Is Made of Rare and Unusual Matter 350

High Tide Comes on Both Sides of Earth at the Same Time 350

On Venus, the Rain Never Falls on the Plain 350

Rocks from Mars Dot Earth 351

Pluto Was Discovered from the Predictions of a Wrong Theory 351

Sunspots Aren’t Dark 351

A Star in Plain View May Have Exploded, But No One Knows 352

The Same Supernova or Quasar May Be Seen in Different Places 352

Chapter 18: Ten Common Errors about Astronomy and Space 353

“The Light from That Star Took 1,000 Light-Years to Reach Earth” 353

There’s No Gravity in Space 354

Summer Comes When Earth Is Closest to the Sun 354

The Back of the Moon Is Dark 354

The “Morning Star” or “Evening Star” Is a Star 355

The Asteroid Belt Is Crowded 355

Nuking a “Killer Asteroid” on a Collision Course for Earth Will Save Us 355

The Sun Is an Average Star 356

The Hubble Space Telescope Gets Up Close and Personal 356

The Big Bang Is Dead 356

Part 6: Appendixes 357

Appendix A: Star Maps 359

Appendix B: Glossary 367

Index 373