Astronomy For Dummies

Stephen P. Maran, PhD, is the retired assistant director of space sciences for information and outreach at the NASA-Goddard Space Flight Center. An investigator of stars, nebulae, and comets, he worked on the Hubble Space Telescope, Space Shuttle missions, Skylab, and other NASA projects.

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 9

They wondered as they wandered: Understanding planets versus stars 10

If you see a Great Bear, start worrying: Naming stars and constellations 10

What do I spy? Spotting the Messier Catalog and other sky objects 18

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

Looking back on light-years 19

Keep on moving: Figuring the positions of the stars 22

Gravity: A Force to Be Reckoned With 25

Space: A Commotion of Motion 26

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 34

Ogling the observatories 35

Popping in on planetariums 38

Vacationing with the Stars: Star Parties, Eclipse Trips, Dark Sky Parks, and More 38

Party on! Attending star parties 39

Getting festive at an AstroFest 40

Tapping into Astronomy on Tap 40

To the path of totality: Taking eclipse cruises and tours 40

Motoring to telescope motels 42

Setting up camp at dark sky parks 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 50

Beginning with Naked-Eye Observation 52

Using Binoculars or a Telescope for a Better View 55

Binoculars: Sweeping the night sky 56

Telescopes: When closeness counts 60

Planning Your First Steps into Astronomy 66

Chapter 4: Just Passing Through: Meteors, Comets, and Artificial Satellites 69

Meteors: Wishing on a Shooting Star 70

Spotting sporadic meteors, fireballs, and bolides 72

Watching a radiant sight: Meteor showers 74

Comets: The Lowdown on Dirty Ice Balls 79

Making heads and tails of a comet’s structure 80

Waiting for the “comets of the century” 84

Hunting for the great comet 86

Artificial Satellites: Enduring a Love–Hate Relationship 88

Skywatching for artificial satellites 89

Finding satellite viewing predictions 91

Part 2: Going Once Around the Solar System 93

Chapter 5: A Matched Pair: Earth and Its Moon 95

Putting Earth under the Astronomical Microscope 96

One of a kind: Earth’s unique characteristics 96

Spheres of influence: Earth’s distinct regions 99

Examining Earth’s Time, Seasons, and Age 101

Orbiting for all time 102

Tilting toward the seasons 103

Estimating Earth’s age 105

Making Sense of the Moon 106

Get ready to howl: Identifying phases of the Moon 107

In the shadows: Watching lunar eclipses 110

Cultivating an interest in the occult(ations) 111

Hard rock: Surveying lunar geology 112

Quite an impact: Considering a theory about the Moon’s origin 117

Chapter 6: Earth’s Near Neighbors: Mercury, Venus, and Mars 119

Mercury: Weird, Hot, and Mostly Metal 120

Dry, Acidic, and Hilly: Steering Clear of Venus 121

Red, Cold, and Barren: Uncovering the Mysteries of Mars 123

Where has all the water gone? 124

Does Mars support life? 126

Differentiating Earth through Comparative Planetology 128

Observing the Terrestrial Planets with Ease 129

Understanding elongation, opposition, and conjunction 130

Viewing Venus and its phases 132

Watching Mars as it loops around 134

Outdoing Copernicus by observing Mercury 138

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

Taking a Brief Tour of the Asteroid Belt 141

Understanding the Threat That Near-Earth Objects Pose 145

When push comes to shove: Nudging an asteroid 147

Forewarned is forearmed: Surveying NEOs to protect Earth 148

Searching for Small Points of Light 149

Helping to track an occultation 150

Timing an asteroidal occultation 151

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 161

Storm chasing across Saturn 162

Monitoring a moon of major proportions 163

Venting about geysers on Enceladus 165

Chapter 9: Far Out! Uranus, Neptune, Pluto, and Beyond 167

Breaking the Ice with Uranus and Neptune 167

Bull’s-eye! Tilted Uranus and its features 168

Against the grain: Neptune and its biggest moon 169

Meeting Pluto, the Amazing Dwarf Planet 170

Getting to the heart of Pluto 171

Looking at Pluto’s makeup 173

The moon chip doesn’t float far from the planet 174

Buckling Down to the Kuiper Belt 175

Viewing the Outer Planets 176

Sighting Uranus 176

Distinguishing Neptune from a star 177

Straining to see Pluto 178

Hunting New Planet Number Nine 178

Part 3: Meeting Old Sol and Other Stars 181

Chapter 10: The Sun: Star of Earth 183

Surveying the Sunscape 184

The Sun’s size and shape: A great bundle of gas 185

The Sun’s regions: Caught between the core and the corona 185

Solar activity: What’s going on out there? 187

Solar wind: Playing with magnets 191

Solar CSI: The mystery of the missing solar neutrinos 192

Four billion and counting: The life expectancy of the Sun 193

Don’t Make a Blinding Mistake: Safe Techniques for Solar Viewing 194

Viewing the Sun by projection 194

Viewing the Sun through front-end filters 198

Fun with the Sun: Solar Observation 200

Tracking sunspots 200

Experiencing solar eclipses 202

Looking at solar pictures on the Net 206

Chapter 11: Taking a Trip to the Stars 209

Life Cycles of the Hot and Massive 210

Young stellar objects: Taking baby steps 211

Main sequence stars: Enjoying a long adulthood 212

Red giants: Burning out the golden years 213

Closing time: Coming up on the tail end of stellar evolution 213

Star Color, Brightness, and Mass 219

Spectral types: What color is my star? 220

Star light, star bright: Luminosity classifications 221

The brighter they burn, the bigger they swell: Mass determines class 222

The H-R diagram 223

Eternal Partners: Binary and Multiple Stars 225

Binary stars and the Doppler effect 225

Two stars are binary, but three’s a crowd: Multiple stars 228

Change Is Good: Variable Stars 230

Go the distance: Pulsating stars 231

Explosive neighbors: Flare stars 232

Nice to nova: Exploding stars 233

Stellar hide-and-seek: Eclipsing binary stars 235

Hog the starlight: Microlensing events 236

Your Stellar Neighbors 237

How to Help Scientists by Observing the Stars 239

Star Studies to Aid with Your Brain and Computer 240

Chapter 12: Galaxies: The Milky Way and Beyond 241

Unwrapping the Milky Way 241

How and when did the Milky Way form? 243

What shape is the Milky Way? 243

Where can you find the Milky Way? 245

Star Clusters: Meeting Galactic Associates 246

A loose fit: Open clusters 246

A tight squeeze: Globular clusters 248

Fun while it lasted: OB associations 250

Taking a Shine to Nebulae 250

Picking out planetary nebulae 252

Breezing through supernova remnants 253

Enjoying Earth’s best nebular views 254

Getting a Grip on Galaxies 256

Surveying spiral, barred spiral, and lenticular galaxies 257

Examining elliptical galaxies 258

Looking at irregular, dwarf, and low surface brightness galaxies 259

Gawking at great galaxies 260

Discovering the Local Group of Galaxies 263

Checking out clusters of galaxies 263

Sizing up superclusters, cosmic voids, and Great Walls 264

Joining Galaxy Zoo for Fun and Science 265

Chapter 13: Digging into Black Holes and Quasars 267

Black Holes: Keeping Your Distance 267

Looking over the black hole roster 268

Poking around the black hole interior 269

Surveying a black hole’s surroundings 271

Warping space and time 272

Detecting black hole collisions 274

Watching stars get swallowed by black holes 275

Quasars: Defying Definitions 276

Measuring the size of a quasar 277

Getting up to speed on jets 277

Exploring quasar spectra 278

Active Galactic Nuclei: Welcome to the Quasar Family 278

Sifting through different types of AGN 278

Examining the power behind AGN 280

Proposing the Unified Model of AGN 281

Part 4: Pondering the Remarkable Universe 283

Chapter 14: Is Anybody Out There? SETI and Planets of Other Suns 285

Using Drake’s Equation to Discuss SETI 286

SETI Projects: Listening for E T 289

The flight of Project Phoenix 290

Space scanning with other SETI projects 291

Hot targets for SETI 292

SETI wants you! 293

Discovering Alien Worlds 293

Changing ideas on exoplanets 294

Finding exoplanets 295

Meeting the (exo)planets 298

Catching Proxima fever: Focusing on red dwarfs 300

Finding Earth-class planets orbiting TRAPPIST-1 302

Checking out planets for fun and science 303

Astrobiology: How’s Life on Other Worlds? 304

Extremophiles: Living the hard way 304

Seeking life in the solar system 305

Chapter 15: Delving into Dark Matter and Antimatter 309

Dark Matter: Understanding the Universal Glue 309

Gathering the evidence for dark matter 310

Debating the makeup of dark matter 314

Taking a Shot in the Dark: Searching for Dark Matter 315

Looking for WIMPs and other microscopic dark matter 316

MACHOs: Making a brighter image 317

Mapping dark matter with gravitational lensing 318

Dueling Antimatter: Proving That Opposites Attract 319

Chapter 16: The Big Bang and the Evolution of the Universe 321

Evidence for the Big Bang 322

Inflation: A Swell Time in the Universe 324

Something from nothing: Inflation and the vacuum 325

Falling flat: Inflation and the shape of the universe 325

Dark Energy: The Universal Accelerator 326

Universal Info Pulled from the Cosmic Microwave Background 327

Finding the lumps in the cosmic microwave background 328

Mapping the universe with the cosmic microwave background 328

In a Galaxy Far Away: Standard Candles and the Hubble Constant 330

Standard candles: How do scientists measure galaxy distances? 330

The Hubble constant: How fast do galaxies really move? 331

The Fate of the Universe 332

Part 5: The Part of Tens 333

Chapter 17: Ten Strange Facts about Astronomy and Space 335

You Have Tiny Meteorites in Your Hair 335

A Comet’s Tail Often Leads the Way 336

Earth Is Made of Rare and Unusual Matter 336

High Tide Comes on Both Sides of Earth at the Same Time 336

On Venus, the Rain Never Falls on the Plain 336

Rocks from Mars Dot Earth 337

Pluto Was Discovered from the Predictions of a False Theory 337

Sunspots Aren’t Dark 337

A Star in Plain View May Have Exploded, but No One Knows 338

You May Have Seen the Big Bang on an Old Television 338

Chapter 18: Ten Common Errors about Astronomy and Space 339

“The Light from That Star Took 1,000 Light-Years to Reach Earth” 339

A Freshly Fallen Meteorite Is Still Hot 340

Summer Always Comes When Earth Is Closest to the Sun 340

The Back of the Moon Is Dark 340

The “Morning Star” Is a Star 340

If You Vacation in the Asteroid Belt, You’ll See Asteroids All Around You 341

Nuking a “Killer Asteroid” on a Collision Course for Earth Will Save Us 341

The Sun Is an Average Star 342

The Hubble Telescope Gets Up Close and Personal 342

The Big Bang Is Dead 342

Part 6: Appendixes 343

Appendix A: Star Maps 345

Appendix B: Glossary 353

Sky Measures 356

Index 357