This edition has been developed with the expert input of more than 150 introductory astronomy instructors nationwide. Discovering Astronomy addresses, in detail, the five concepts identified as most difficult for students to grasp:
- big bang cosmology
- stellar evolution
- gravity
- light and spectra
- mathematical concepts
The pedagogy strengthens critical reasoning and evaluation skills, leading to a clearer understanding of the process of science, and enhancing students' abilities to apply scientific concepts in new contexts.
The fifth edition includes recent results from the Mars orbiters and landers, and the Cassini mission to Saturn. Hubble Space Telescope results are discussed when appropriate. The discussion of extrasolar planets has been updated and expanded significantly.
This text engages students in active involvement in their own learning process. One way the book achieves active involvement is through the inclusion of numerous "Inquiries" within the reading. These "Inquiries" purposely break up the reading so the student stops and thinks about what's been read before continuing. Answers to these "Inquiries" at the end of each chapter allow students to gauge their understanding.
Also Available for Adopters
- Instructor's Manual
- Test Bank
- Animation Links
- Tabbing Guide
PART ONE: Discovering the Science of Astronomy
Chapter 1: Beyond the Blue Horizon: A Grand Tour of the Universe
1.1 What Is Astronomy?
1.2 Our View of the Cosmos
Astronomy Uses Large and Small Numbers
1.3 The Solar System
The Star of the Solar System
The Earth-like Planets
The Giant Planets
The Outer Reaches of the Solar System
Planets around Other Stars
1.4 Stars, Galaxies, and Beyond
Interstellar Material and Star Formation
Stellar Evolution
Clusters of Stars
Galaxies
Clusters of Galaxies
The Universe as a Whole
1.5 Where Does Astronomy Go from Here?
Chapter Summary
Summary Questions
Applying Your Knowledge
Answers to Inquiries
Chapter 2: Science and Pseudoscience
2.1 An Expedition to Earth
2.2 Astronomy as an Observational Science
The Process of Doing Astronomy
The Astronomer's Challenge
The Astronomical Time Machine
2.3 Science as a Process
The Explosion of Knowledge in the Twentieth Century
From Idea to Textbook - How Science Proceeds
Two Examples of Science as a Process
2.4 Is It Science or Pseudoscience?
The "Game" of Science
Is the Hypothesis at Risk?
Don't Confuse Me with the Facts
Simple Answers to Complex Problems
Playing the Underdog
Conspiracy Theories
Playing on Fear and Emotion
Do They Do Research?
For Whom Do They Write?
2.5 Do New Ideas Displace the Old Ones?
Concluding Thoughts
Chapter Summary
Summary Questions
Applying Your Knowledge
Answers to Inquiries
Further Readings
Chapter 3: Astronomical Observations: Angles and Uncertainties
3.1 Angles and Angular Measurement
3.2 Angles on the Celestial Sphere
3.3 The Relationship between True and Apparent Size
Solar Eclipses
3.4 Measurement Uncertainty in Science
Precision and Accuracy
Random Uncertainties
Systematic Uncertainty
3.5 Systematic Uncertainties in Astronomy: The Kapteyn Universe as an Example
Discovery 3-1: Measuring Your Room
Chapter Summary
Summary Questions
Applying Your Knowledge
Answers to Inquiries
Chapter 4: Basic Observations and Interpretations of the Sky
4.1 Early Observations of the Sky
4.2 Early Greek Observations: The Round Earth
4.3 The Observed Motions of the Sky
The Celestial Sphere: A Model of the Sky
4.4 The Motion of the Sun
The Daily Motion
The Motion of the Sun in Relation to the Stars
Solar and Sidereal Days
4.5 The Reasons for the Seasons
4.6 The Location of Stars on the Celestial Sphere
Precession
4.7 The Motion and Phases of the Moon
The Motion of the Moon
The Phases of the Moon
Eclipses
4.8 The Motions of the Planets
4.9 How Stars Get Their Names
4.10 The Brightness of Stars
Appendix: Observing Hints and the Use of Star Charts
Brightness of Stars
Observing Stars in the Northern Part of the Sky
The Northern Sky in September
The Northern Sky at Other Times of the Year
Observing the Rest of the Sky: Using the Star Maps
Observing Tips
Chapter Summary
Summary Questions
Applying Your Knowledge
Answers to Inquiries
Chapter 5: The Historical Quest to Model the Solar System
5.1 Greek Astronomy
What the Greeks Inherired
Aristotle
Aristarchus of Samos
Eratosthenes
Hipparchus
Other Deductions of the Greek Astronomers:
The Distances of the Planets
The Apparent Motions of the Planets in Relation to the Stars
The Geocentric Model of the Solar System
The Hypothesis of Circulai Motion
Ptolemy
5.2 Astronomy during the Middle Ages
5.3 The Heliocentric Hypothesis
Nicolaus Copernicus
Tycho Brahe
Johannes Kepler
5.4 Kepler's Laws of Planetary Motion
5.5 The Search for Underlying Laws
Galileo Galilei
Isaac Newton
Newton's Law of Gravity
Weight
Momentum
Newton's Generalization of Orbital Motion
Newton's Form of Kepler's Third Law
Successes of Newton's Laws
5.6 Evidence in Favor of the Heliocentric Hypothesis
5.7 Observational Evidence of the Earth's Rotation
Foucault Pendulum
Coriolis Effects: Additional Evidence for a Spinning Earth
Precession and the Rotating Earth
Discovery 5-1 : Weightlessness
Chapter Summary
Summary Questions
Applying Your Knowledge
Answers to Inquiries
PART TWO: Discovering the Nature and Evolution of Planetary Systems
Chapter 6: The Structure and Formation of Planetary Systems
6.1 An Overview of the Solar System
6.2 Observations: Orbital Patterns
6.3 The Distribution of Angular Momentum
6.4 Hypotheses of the Origin of the Solar System
A Simple Hypothesis That Does Not Work
Evolutionary Hypotheses
Catastrophic Hypotheses
Additional Hypotheses
6.5 Modern Ideas
Energy and Solar System Formation
The Role of Dust Grains in Planet
Formation
Chemical Composition
Bringing It All Together
Refinements of the Theory
Leftover Odds and Ends
The Angular Momentum Problem
Which Hypothesis of Solar System Formation is Preferred?
Model Solar Systems
6.6 Other Planetary Systems
Methods of Search and Discovery
Properties of Extrasolar Planets and Their Stars
Discovery 6-1: A Scale Model of the Solar System
Chapter Summary
Summary Questions
Applying Your Knowledge Answers to Inquiries
Chapter 7: The Smallest Bodies of the Solar System: Comets, Minor Planets, and Meteorites
7.1 Comets
The Structure of Comets
The Dirty Snowball Model
Orbits of Comets
The Oort and Kuiper Comet Clouds
Spacecraft Studies of Comets
Future Spacecraft Studies of Comets
7.2 Minor Planets
Characteristics of the Minor Planets
Orbits of the Minor Planets
The Trojans and the Kirkwood Gaps
Why Are the Minor Planets So Small?
Chemical Composition
Future Spacecraft Studies of Asteroids
7.3 Meteors, Meteor Showers, and Meteorites
Meteorite Craters
Did an Asteroid or Comet Impact Send the Dinosaurs into Extinction?
Meteor Showers
7.4 Interplanetary Dust
7.5 Meteorites and the Early Solar System
Chemical Composition
Internal Structure
The Origin of Meteorites
Meteorite Dating
Did a Supernova Explosion Trigger the Formation of Our Solar System?
Discovery 7-1: Asteroid Brightness Variations
Chapter Summary
Summary Questions
Applying Your Knowledge
Answers to Inquiries
Chapter 8: The Earth and Moon: Processes and Facts
8.1 Earth as an Astronomical Body
Determination of Basic Properties
8.2 Earth's Interior
Seismic Studies
Plate Tectonics
The Source of Heat in the Interior
8.3 Earth's Surface
Rock Types, Processes, and Ages
Chemical Composition
Volcanism
Mountains
Impact Craters
Ocean Tides
Water
8.4 Earth's Atmosphere
The Greenhouse Effect
Atmospheric Circulation
Origin and Maintenance of the Atmosphere
8.5 Earth's Magsnetism
8.6 The Moon: Large-Scale Characteristics
8.7 The Moon's Atmosphere
8.8 The Lunar Surface
General Surface Characteristics
Craters
Maria and Highlands
Surface Movement
Lava Channels and Tubes
The Composition and Structure of the Lunar Surface Material
The Age of the Lunar Surface
8.9 The Moon's Interior
8.10 The Origin of the Moon
8.11 Tides and the Future of the Earth--Moon System
8.12 Understanding the Universe Using the Moon
Discovery 8-1: Lunar Surface Features as Seen from Earth
Chapter Summary
Summary Questions
Applying Your Knowledge
Answers to Inquiries
Chapter 9: The Earth-like Planets
9.1 Introduction to the Terrestrial Planets
Early Ground-Based Studies
Planetary Space Exploration
9.2 Large-Scale Characteristics
Orbits
Rotation
Basic Properties: Size, Mass, Density
Seasons
9.3 Atmospheres
Atmospheric Chemical Composition
Atmospheric Temperature
Atmospheric Pressure
Lightning
Clouds
Atmospheric Circulation
Why Do the Atmospheric Compositions Differ So Much?
9.4 Surfaces
The View from Orbit
The View from the Surface
Surface Temperatures
Surface Compositions
Water
Craters
Impact Basins
Continents, Mountains, and Volcanoes
Faults, Tectonics, Cliffs, and Valleys
Wind Erosion
Polar Regions
9.5 Interiors
Magnetic Fields
Interior Structures
9.6 Moons
9.7 Evolutionary Comparison
9.8 Future Studies
Chapter Summary
Summary Questions
Applying Your Knowledge
Answers to Inquiries
The Planets One-by-One
Chapter 10: The Jovian Planets and Pluto
10.1 Introduction
An Overview of Ground-Based Studies
Space Exploration of Jovian Planets
10.2 Large-Scale Characteristics
Orbits and Rotation
Size, Mass, Density
Seasons
Excess Energy
10.3 Atmospheres
Appearance and Circulation
Chemical Composition
10.4 Planetary Interiors
Magnetic Fields
Interior Structure
10.5 Moons
The Moons of Jupiter
The Moons of Saturn
The Moons of Uranus
The Moons of Neptune
10.6 Planetary Rings
10.7 Pluto
10.8 Future Studies of the Outer Solar System
Future Space Probes
Are There Planets beyond Pluto?
Chapter Summary
Summary Questions
Applying Your Knowledge
Answers to Inquiries
The Planets One-by One
PART THREE: Discovering the Techniques of Astronomy
Chapter 11: The Nature of Light
11.1 Light as a Ray
Reflection
Refraction
11.2 Light as a Wave Diffraction
Interference
Electromagnetic Radiation
The Speed of Light
Speed, Frequency, and Wavelength
Polarization
11.3 Light as a Stream of Particles
The Photoelectric Effect
Models of Light
Discovery 11-1: Images in a Mirror
Discovery 11-2: Refraction of Light
Chapter Summary
Summary Questions
Applying Your Knowledge
Answers to Inquiries
Chapter 12: Telescopes: Our Eyes of Discovery
12.1 The Formation of Images
12.2 Telescopes
The Light-Gathering Power of a Telescope
Resolving Power
Magnification
The Mounting of a Telescope
12.3 Comparing Reflecting and Refracting Telescopes
12.4 Reflecting Telescopes of Various Types
12.5 The Telescopes of the Future
Efforts to Overcome the Unsteady Atmosphere
12.6 Detectors and Instruments
Cameras and Film
Photoelectric Photometers
Modern Electronic Detectors
12.7 Radio Astronomy
Interferometers
12.8 Optical and Radio Observatory Sites
12.9 Beyond Optical and Radio Astronomy
12.10 NASA's Great Observatories
The Hubble Space Telescope
The Compton Gamma-Ray Observatory
The Chandra X-Ray Observatory
The Spitzer Space Telescope
The Future
Chapter Summary
Summary Questions
Applying Your Knowledge
Answers to Inquiries
Chapter 13: Spectra: The Key to Understanding the Universe
13.1 Observations of Spectra
The Principle of the Spectrometer
The Continuous Spectrum: Kirchhoff's First Law
The Dependence of the Continuous Spectrum on Temperature
The Laws of Blackbody Radiation
Objects Can Be Seen by Their Emitted Light or Their Reflected Light
Emission Spectra: Kirchhoff's Second Law
The Spectral Fingerprints of the Chemical Elements
The Sun's Absorption Spectrum: Kirchhoffs Third Law
13.2 Understanding Spectra
Energy-Level Diagram of the Hydrogen Atom
Why Different Elements Have Different Spectra
Atomic Explanation of Kirchhoff's Laws
13.3 Applications of Spectroscopy
A Model of the Sun Based on Its Spectrum
The Sun's Flash Spectrum
lonized Gas between the Stars
The Nature of Nebulae
Forbidden-Line Emission
Neutral Gas between the Stars: Interstellar Absorption Lines
Chapter Summary
Summary Questions
Applying Your Knowledge
Answers to Inquiries
PART FOUR
Discovering the Nature and Evolution of Stars
Chapter 14: Understanding Stellar Spectra
14.1 Classification of Stellar Spectra
Modern Classification
Why Should Spectra Vary in Appearance?
Observations of Stellar Spectra
14.2 The Cosmic Abundance of the Chemical Elements
14.3 The Doppler Effect
14.4 What We Can Learn from Spectral Lines
Thermal Broadening
Rotation of Stars
Density in a Stellar Atmosphere
Atmospheric Turbulence
Magnetic Fields in Stars
Binary Stars
A Final Example of Stellar Spectra
Discovery 14-1: Classification of Stellar Spectra
Chapter Summary
Summary Questions
Applying Your Knowledge
Answers to Inquiries
Chapter 15: The Observed Properties of Normal Stars
15.1 Distance Measurements
Variation of Stellar Brightness with Distance
15.2 Binary Stars
Visual Binaries
Spectroscopic Binaries
Eclipsing Binaries
15.3 Other Studies of Stellar Radii
Lunar Occultations
Optical Interferometry
Densities of Stars
15.4 The Hertzsprung-Russell Diagram
A Graphing Experiment
Introduction to the Hertzsprung-Russell Diagram
The Nearest Stars
The Brightest Stars
Interpreting the Hertzsprung-Russell Diagram
15.5 Main-Sequence, Giant, Supergiant, and White Dwarf Stars
15.6 Explanation of the Main Sequence
The Mass-Luminosity Relation
Densities of Stars: A Reprise
15.7 Stellar Distances and the H-R Diagram
Discovery 15-1: Visual Binary Stars
Discovery 15-2: Spectroscopic Binary Stars
Chapter Summary
Summary Questions
Applying Your Knowledge
Answers to Inquiries
Chapter 16: The Sun and Stars: Their Energy Sources and Structure
16.1 The Power Produced by the Sun
16.2 Energy Sources
Chemical Reactions
Gravitational Collapse
Nuclear Reactions: Fission versus Fusion
The Proton-Proton Chain
The Carbon-Nitrogen-Oxygen Cycle
16.3 The Conditions Required for Fusion
Temperatures and Densities
16.4 Antimatter and Neutrinos
16.5 Stellar Structure
Pressure and Energy Equilibrium
Energy Transport
Stellar Models
16.6 The Lifetimes of Stars
16.7 The Sun - A Typical Star
The Photosphere
The Convective Zone
Sunspots
The Sun's Magnetic Field
The Chromosphere
The Corona
The Solar Wind
Flares and Other Surface Activity on the Sun
Solar-Terrestrial Connections
Solar Oscillations
Discovery 16-1: Solar Granulation
Chapter Summary
Summary Questions
Applying Your Knowledge
Answers to Inquiries
Chapter 17: Star Formation and Evolution to the Main Sequence
17.1 Matter for Star Formation
Molecules in the Interstellar Medium
Dust in the Interstellar Medium
The Mixture of Dust and Molecules
The Formation of Molecules in Dust Clouds
The Hydrogen Molecule
Cloud and Cloud Complexes
17.2 Star-Formation: Theory
Initiation of Star Formation
Disk Formation and Accretion
Theoretical Models of Early Stellar Evolution
The Approach to the Main Sequence
17.3 Star-Formation: Observations
Bipolar Nebulae and Accretion Disks
Bok Globules
Infrared Sources
T Tauri Stars
Herbig-Haro Objects
OB Associations
Star Clusters
Brown Dwarfs
17.4 A Prominent Region of Star Formation: The Orion Molecular Cloud Complex and Nebula
Chapter Summary
Summary Questions
Applying Your Knowledge
Answers to Inquiries
Chapter 18: Stellar Evolution After the Main Sequence
18.1 The Mid-Life Evolution of Sunlike Stars
Why Stars Leave the Main Sequence
Becoming a Red Giant
Evolution during the Red Giant Phase
18.2 The Mid-Life Evolution of Stars Less Massive Than the Sun
18.3 The Mid-Life Evolution of Stars More Massive Than Eight Solar Masses
18.4 Pulsating Stars
18.5 Mass Loss, Binary Stars, and Stellar Evolution
18.6 The Death of Stars Less Than Eight Solar Masses
Planetary Nebulae
Observational Properties of White Dwarfs
The Structure of White Dwarfs
18.7 The Observational Evidence for Stellar Evolution
The Hertzsprung-Russell Diagrams of Star Clusters
Evidence from Spectra Pertaining to Stellar Evolution
A Direct Detection of Stellar Evolution
Chapter Summary
Summary Questions
Applying Your Knowledge
Answers to Inquiries
Chapter 19: Stellar Death and Catastrophes
19.1 Novae
Observations
The Place of Novae in Stellar Evolution
Do Novae Involve Large or Small Stars?
How a Nova Explodes
19.2 Supernova
Observations
Type I Supernova
Type II Supernova and the Late Stages of Massive Stars' Evolution
Synthesis of Heavy Elements in Massive Stars
Confirmation of the Type II Model: Supernova 1987A
19.3 Neutron Stars and Pulsars
Pulsars
Why Pulsars "Pulse"
A Model of a Neutron Star
Binary and Millisecond Pulsars
Magnetars
Planets around Pulsars
19.4 Black Holes
The Theoretical Prediction of Black Holes
Observations of Stellar Black Holes
19.5 Mystery Solved: Beasts in the Cosmic Zoo
Microquasars
Gamma Ray Bursters
A General Model
Chapter Summary
Summary Questions
Applying Your Knowledge
Answers to Inquiries
PART FIVE: Discovering the Nature and Evolution of Galaxies and the Universe
Chapter 20: The Milky Way: Our Galaxy
20.1 Our Place in the Milky Way
The Distribution of Globular Clusters
The Motion of the Sun around the Galaxy
The Mass of Our Galaxy
The Motion of Other Stars
Dark Matter
High-Velocity Stars
20.2 Interstellar Gas and Dust
Interstellar Dust: Extinction of Starlight
Interstellar Dust: Reddening
Interstellar Dust: Reflection Nebulae
Interstellar Dust: Polarization of Sunlight
Interstellar Dust: Thermal Radiation
Interstellar Dust: Chemical Composition and Formation
Interstellar Gas
21-cm Hydrogen Emission
The Structure of the Interstellar Medium
20.3 The Structure of the Milky Way System
Optical Evidence for the Spiral Structure of the Galaxy
Radio Evidence for the Spiral Structure of the Galaxy
The Cause of Spiral Structure
The Density-Wave Theory
The Galactic Halo and the Nuclear Bulge
The Center of the Galaxy
Stellar Populations
20.4 The Formation and Evolution of the Galaxy
The Chemical Evolution of the Galaxy
The Formation of the Milky Way
20.5 The Galactic Magnetic Field
20.6 Cosmic Rays
Observation of Cosmic Rays
Origin of Cosmic Rays
Discovery 20-1: Galactic Rotation
Discovery 20-2: The Distribution of Different Objects around the Galaxy
Chapter Summary
Summary Questions
Applying Your Knowledge
Answers to Inquiries
Chapter 21: Galaxies
21.1 The Historical Problem of the Nebulae
21.2 The Morphology of Galaxies
Spiral Galaxies
Elliptical Galaxies
Irregular Galaxies
50 Galaxies
Dwarf Galaxies
Hubble's Tuning Fork Diagram
21.3 Distances of the Galaxies
Cepheid Variables
Other Distance Indicators for Galaxies
The Velocity-Distance Relationship
21.4 General Galaxy Attributes
Luminosity
Dimensions
Mass
Magnetic Field
21.5 The Stellar Content of Galaxies
Spiral Galaxies
Elliptical Galaxies
Irregular Galaxies
21.6 The Formation and Evolution of Galaxies
Observational Input
The Density-Angular Momentum Problem
Galaxy Interactions and Mergers
Differences between Spirals: Supernova- Applying Your Knowledge
21.7 Clusters of Galaxies
Our Neighborhood: The Local Group
Larger Clusters: The Cluster Environment and Galaxy Evolution
Masses of Galaxy Clusters
Intergalactic Matter
21.8 Clusters of Clusters: Superclusters
21.9 Cluster and Superciuster Formation
21.10 The Hubble Deep Field and Ultra Deep Field
Discovery 21-1: Distances throughout the Universe
Chapter Summary
Summary Questions
Applying Your Knowledge
Answers to Inquiries
Chapter 22: Peculiar and Unusual Extragalactic Objects
22.1 Peculiar-Looking Galaxies
22.2 Radio Galaxies
Three Bright Radio Galaxies: Cygnus A, Centaurus A, and M87
High-Resolution Observations of Radio Emission from Galaxies
22.3 Seylert Galaxies and Other Active Galaxies
22.4 Quasars
The Spectra, Distances, and Luminosities of Quasars
The Variability of Quasars
The Central Monster
22.5 A Unified Model of AGN
Discovery 22-1: Measuring a Quasar's Redshift
Discovery 22-2: A Scale Model of Distances in the Universe
Chapter Summary
Summary Questions
Applying Your Knowledge
Answers to Inquiries
Chapter 23: The Origin and Evolution of the Universe
23.1 Expansion of the Universe
The Velocity-Distance Relationship
Consequences of the Hubble Law
23.2 The Big Bang
The Three Cornerstones of the Big Bang
The Four Forces of Nature
The Early Moments of the Universe
The Early Universe Leaves Relics
The Epoch of Galaxy Formation
23.3 The Geometry of Space and the Shape of the Universe
What Is Meant by Curved Space?
23.4 The Future of the Universe
The Traditional View
A Cosmic Revolution
23.5 The Early Universe Revisited: Inflation
The Flatness Problem
The Horizon Problem
Inflation
23.6 The Halley-Olbers Paradox
23.7 The Multiverse
Discovery 23-1: The Age of the Universe
Discovery 23-2: The Expansion of the Universe
Discovery 23-3: Observing the Cosmic Background Radiation
Chapter Summary
Summary Questions
Applying Your Knowledge
Answers to Inquiries
PART SIX: Discovering If There Is Life Elsewhere in the Universe
Chapter 24: The Search for Extraterrestrial Life
24.1 What Is Life?
Life on Earth
24.2 The Ingredients for Life
The Extreme Range of Life on Earth
A Source of Energy
Liquid Water
Carbon
24.3 The Search for Extraterrestrial Life Inside Our Solar System
The Moon and Mercury
Venus
Mars
The Jovian Moons
24.4 The Search for Life Outside Our Solar System
Stellar Habitable Zones
Galactic Habitable Zones
The Search for Life on Worlds Outside Our Solar System
24.5 The Search For Extraterrestrial Intelligence
The Historical Search for Extraterrestrial Intelligence
Is Anybody Out There?
Modern Searches for Extraterrestrial Intelligence
Should We Go There?
What Do We Do When We Get There?
Announcing Our Existence to the Universe
Discovery 24-1: Exploring the Conditions For Life
Chapter Summary
Summary Questions
Applying Your Knowledge
Answers to Inquiries
Appendix A: Useful Mathematical Information
1. The Powers of Ten Shorthand for Numbers
2. Some Useful Numbers
3. Relations between Units
4. Conversion between Units
5. Derivation of Angular Size Formula
6. Computing Random Uncertainties
7. Why Bodies of Different Masses Fall at the Same Rate
8. Weight as the Force of Gravity
9. A Further Example of the Doppler Effect
10. Spectroscopic Parallaxes
11. The Relation between Sidereal and Synodic Periods
Appendix B: Constellations
Appendix C: Properties of Planets and Satellites
Appendix D: The 40 Brightest Stars
Appendix E: Stars Nearer Than Al Four Parsecs
Appendix F: Some Local Group Galaxies
Appendix G: Periodic Table of the Elements
Appendix H: Star Maps For the Northern Hemisphere
Glossary
Credits
Index