Explorations: Introduction to Astronomy

Title
Contents
PREVIEW The Cosmic Landscape
	The Earth, Our Home
	The Moon
	The Planets
	The Sun
	The Solar System
	The Astronomical Unit
	The Milky Way Galaxy
	The Light-Year
	Galaxy Clusters and the Universe
	Gravity
	Atoms and Other Forces
	The Still-Unknown Universe
	The Scientific Method
		Projects
1 The Cycles of the Sky
	1.1 The Celestial Sphere
		Constellations
			Daily Motions of the Sun and Stars
			Annual Motion of the Sun
			The Ecliptic and the Zodiac
	1.2 The Seasons
		The Ecliptic’s Tilt
			Solstices and Equinoxes
	1.3 The Moon
		Extending Our Reach: Observing the Moon
	1.4 Eclipses
		Appearance of Eclipses
			Rarity of Eclipses
			Precession of the Moon’s Orbit
			Projects
2 The Rise of Astronomy
	2.1 Early Ideas of the Heavens: Classical Astronomy
		The Shape of the Earth
			The Size of the Earth
			Distance and Size of the Sun and Moon
		Extending Our Reach: Measuring the Diameter of Astronomical Objects
		Extending Our Reach: The Moon Illusion
	2.2 The Planets
		Explaining the Motion of the Planets
			Ptolemy
			Islamic Contributions
			Asian Contributions
	2.3 Astronomy in the Renaissance
		Nicolaus Copernicus
			Tycho Brahe
			Johannes Kepler
	2.4 The Birth of Astrophysics
		Galileo Galilei
			Isaac Newton
			Astronomy and Astrology
			New Discoveries
			New Technologies
			Project
ESSAY 1
	Backyard Astronomy
		Learning the Constellations
		Star Lore
		Amateur Astronomy
		Small Telescopes
		Star Charts
		Celestial Coordinates
		Planetary Configurations
		Your Eyes at Night
			Project
3 Gravity and Motion
	3.1 Inertia
	3.2 Orbital Motion and Gravity
	3.3 Newton’s Second Law of Motion
		Acceleration
			Mass
	3.4 The Law of Gravity
	3.5 Newton’s Third Law of Motion
	3.6 Measuring an Object’s Mass Using Orbital Motion
	3.7 Surface Gravity
		Extending Our Reach: Weighing the Sun
	3.8 Escape Velocity
		Project
4 Light and Atoms
	4.1 Properties of Light
		The Nature of Light—Waves or Particles?
			Light and Color
			Characterizing Electromagnetic Waves by Their Frequency
			White Light
	4.2 The Electromagnetic Spectrum: Beyond Visible Light
		Infrared Radiation
			Ultraviolet Light
			Radio Waves
			Other Wavelength Regions
			Energy Carried by Electromagnetic Radiation
	4.3 The Nature of Matter and Heat
		The Kelvin Temperature Scale
			Temperature and Radiation
		Extending Our Reach: Taking the Temperature of the Sun
	4.4 Radiation from Individual Atoms
		The Chemical Elements
			Electron Orbitals
			The Generation of Light by Atoms
	4.5 Formation of a Spectrum
		How a Spectrum Is Formed
			Identifying Atoms by Their Light
			Types of Spectra
			Astronomical Spectra
	4.6 The Doppler Shift: Detecting Motion
	4.7 Absorption in the Atmosphere
		Extending Our Reach: Observing the Crab Nebula at Many Wavelengths
			Projects
ESSAY 2
	Special and General Relativity
		Rest Frames
		The Speed of Light from Moving Objects
		The Michelson-Morley Experiment
		Einstein’s Theory of Special Relativity
		Special Relativity and Space Travel
		The Twin Paradox
		Rethinking Gravity
		General Relativity
5 Telescopes
	5.1 Telescopes
		Light-Gathering Power
			Focusing the Light
		Extending Our Reach: Refraction
	5.2 Resolving Power
		Interferometers
	5.3 Detecting Light
		Visible Light
			Observing at Nonvisible Wavelengths
	5.4 Telescopes on the Ground and in Space
		Atmospheric Blurring
		Extending Our Reach: Exploring New Wavelengths: Gamma Rays
			Space Telescopes Versus Ground-Based Telescopes
	5.5 Observatories
		Going Observing
			Computers
			Projects
6 The Earth
	6.1 The Earth as a Planet
		Shape and Size of the Earth
			Composition of the Earth
			Density of the Earth
		Extending Our Reach: Measuring the Earth’s Mass
	6.2 The Earth’s Interior
		Probing the Interior with Earthquake Waves
			Heating of the Earth’s Core
	6.3 The Age of the Earth
	6.4 Motions in the Earth’s Interior
		Convection in the Earth’s Interior
			Plate Tectonics
	6.5 The Earth’s Magnetic Field
		Origin of the Earth’s Magnetic Field
			Magnetic Effects on Cosmic Particles
		Extending Our Reach: Measuring Reversals of the Earth’s Magnetic Field
	6.6 The Earth’s Atmosphere
		Structure of the Atmosphere
			Composition of the Atmosphere
			The Greenhouse Effect
			The Ozone Layer
			Origin of the Atmosphere
	6.7 Motions of the Earth
		Air and Ocean Circulation: The Coriolis Effect
			Precession
			Projects
ESSAY 3
	Keeping Time
		Hours of Daylight
		The Day
		Time Zones
		Universal Time
		Daylight Saving Time
		The Week
		The Month
		The Calendar
		Leap Year
		Religious Calendars
		Other Calendars
		Moon Lore
		The Abbreviations A.M., P.M., B.C., A.D., B.C.E., and C.E.
7 The Moon
	7.1 The Surface of the Moon
		Surface Features
			Origin of Lunar Surface Features
	7.2 Structure of the Moon
		Crust and Interior
			The Absence of a Lunar Atmosphere
	7.3 Orbit and Motions of the Moon
		The Moon’s Rotation
			Oddities of the Moon’s Orbit
	7.4 Origin and History of the Moon
	7.5 Tides
		Cause of Tides
			Solar Tides
			Tidal Braking
			Projects
8 Survey of Solar Systems
	8.1 Components of the Solar System
		The Sun
			The Orbits and Spins of the Planets
			Two Types of Planets
			Satellites
			Asteroids and Comets
			Composition Differences Between the Inner and Outer Planets
			Density as a Measure of a Planet’s Composition
			Age of the Solar System
		Extending Our Reach: Bode’s Rule: The Search for Order
	8.2 Formation of Planetary Systems
		Interstellar Clouds
			Formation of the Solar Nebula
			Condensation in the Solar Nebula
			Accretion and Planetesimals
			Formation of the Planets
			Final Stages of Planet Formation
			Formation of Satellite Systems
			Formation of Atmospheres
		Science at Work: Direct Formation of Giant Planets
			Cleaning Up the Solar System
	8.3 Other Planetary Systems
		Science at Work: Migrating Planets
			Project
9 The Terrestrial Planets
	9.1 Mercury
		Mercury’s Temperature and Atmosphere
		Mercury’s Interior
		Mercury’s Rotation
	9.2 Venus
		The Venusian Atmosphere
		The Greenhouse Effect
		The Surface of Venus
		The Interior of Venus
		Rotation of Venus
	9.3 Mars
		The Surface of Mars
		Water on Mars
		The Martian Atmosphere
		The Martian Interior
		The Martian Moons
		Life on Mars?
	9.4 Why Are the Terrestrial Planets So Different?
		Role of Mass and Radius
		Role of Internal Activity
		Role of Sunlight
		Role of Water Content
		Role of Biological Processes
10 The Outer Planets
	10.1 Jupiter
		Jupiter’s Appearance and Physical Properties
		Jupiter’s Interior
		Jupiter’s Atmosphere
		Jupiter’s Rings
		Jupiter’s Moons
	10.2 Saturn
		Saturn’s Appearance and Physical Properties
		Saturn’s Rings
		Origin of Planetary Rings
		The Roche Limit
		Saturn’s Moons
	10.3 Uranus
		Uranus’s Structure
			Uranus’s Odd Tilt
			Uranus’s Rings and Moons
	10.4 Neptune
		Neptune’s Structure
			Neptune’s Atmosphere
			Neptune’s Rings and Moons
	10.5 Pluto and Beyond
11 Meteors, Asteroids, and Comets
	11.1 Meteors, Meteoroids, and Meteorites
		Heating of Meteoroids
			Types of Meteorites
	11.2 Asteroids
		Size and Shape
			Composition
			Origin of Asteroids
			Unusual Asteroids
	11.3 Comets
		Structure of Comets
			Composition of Comets
			Origin of Comets
			Formation of the Comet’s Tail
			Short-Period Comets and the Kuiper Belt
			Fate of Short-Period Comets
			Meteor Showers
	11.4 Giant Impacts
		Giant Meteor Craters
		Science at Work: Meteorites Can Be Deadly
		Science at Work: Ghost Craters, or No Tell-Tale Fragments
			Mass Extinction and Asteroid/Comet Impacts
			Projects
12 The Sun, Our Star
	12.1 Size and Structure
		Measuring the Sun’s Properties
			The Solar Interior
			Energy Flow in the Sun
			The Solar Atmosphere
	12.2 How the Sun Works
		Internal Balance (Hydrostatic Equilibrium)
			Pressure in the Sun
			Powering the Sun
				Nuclear Fusion
				The Structure of Hydrogen and Helium
				The Proton–Proton Chain
	12.3 Probing the Sun’s Core
		Solar Neutrinos
			Solar Seismology
		Science at Work: Solving the Neutrino Puzzle
	12.4 Solar Magnetic Activity
		Sunspots
			Solar Magnetic Fields
			Prominences and Flares
		Extending Our Reach: Detecting Magnetic Fields: The Zeeman Effect
			Heating of the Chromosphere and Corona
			The Solar Wind
	12.5 The Solar Cycle
		Cause of the Solar Cycle
			Changes in the Solar Cycle
			Links Between the Solar Cycle and Terrestrial Climate
			Projects
13 Measuring the Properties of Stars
	13.1 Measuring a Star’s Distance
		Measuring Distance by Triangulation and Parallax
		Extending Our Reach: Measuring the Distance to Sirius
			Measuring Distance by the Standard- Candles Method
	13.2 Measuring the Properties of Stars from Their Light
		Temperature
			Luminosity
			The Inverse-Square Law and Measuring a Star’s Luminosity
			Radius
			The Stefan-Boltzmann Law
		Extending Our Reach: Measuring the Radius of the Star Sirius
			The Magnitude System
	13.3 Spectra of Stars
		Measuring a Star’s Composition
			How Temperature Affects a Star’s Spectrum
			Classification of Stellar Spectra
		Science at Work: New Spectral Types
			Definition of the Spectral Types
			Measuring a Star’s Motion
	13.4 Binary Stars
		Visual and Spectroscopic Binaries
			Measuring Stellar Masses with Binary Stars
			Eclipsing Binary Stars
	13.5 Summary of Stellar Properties
	13.6 The H-R Diagram
		Constructing the H-R Diagram
			Analyzing the H-R Diagram
			Giants and Dwarfs
			The Mass–Luminosity Relation
			Luminosity Classes
			Summary of the H-R Diagram
	13.7 Variable Stars
	13.8 Finding a Star’s Distance by the Method of Standard Candles
		Project
14 Stellar Evolution
	14.1 Overview of Stellar Evolution
		The Importance of Gravity
			The Life Story of the Sun—A Low-Mass Star
			The Life Story of a High-Mass Star
			Stellar Recycling
	14.2 Star Formation
		Interstellar Gas Clouds
			Protostars
			Bipolar Flows from Young Stars
			Stellar Mass Limits
	14.3 Main-Sequence Stars
		Why a Star’s Mass Determines Its Core Temperature
			Structure of High-Mass and Low-Mass Stars
			Main-Sequence Lifetime of a Star
	14.4 Giant Stars
		Leaving the Main Sequence
			Nuclear Fuels Heavier Than Hydrogen
			Degeneracy in Low-Mass Stars
	14.5 Yellow Giants and Pulsating Stars
		Why Do Stars Pulsate?
			The Period–Luminosity Law
	14.6 Death of Stars Like the Sun
		Ejection of a Low-Mass Star’s Outer Layers
			Planetary Nebulas
		Science at Work: Planetary Nebulas
			The Fates of Other Low-Mass Stars
	14.7 Old Age of Massive Stars
		Formation of Heavy Elements: Nucleosynthesis
			Core Collapse of Massive Stars
			Supernova Explosions
			Supernova Remnants
	14.8 History of Stellar Evolution Theories
		Early Stellar Models
		Extending Our Reach: Measuring the Age of a Star Cluster
			Testing Stellar Evolution Theory
			Project
15 Stellar Remnants: White Dwarfs, Neutron Stars, and Black Holes
	15.1 White Dwarfs
		General Properties, Origin, and Fate
			Structure of White Dwarfs
			Degeneracy and the Chandrasekhar Limit
			White Dwarfs in Binary Systems: Novas and Supernovas of Type Ia
	15.2 Neutron Stars
		General Properties and Origin
			Pulsars and the Discovery of Neutron Stars
			Emission from Neutron Stars
			Structure of Neutron Stars
			Neutron Stars in Binary Systems
			X-Ray Binary Stars
			Gravitational Waves from Binary Neutron Stars
	15.3 Black Holes
		The Nature of Space Around Black Holes
			The Formation and Observation of Black Holes
			Hawking Radiation
			Projects
16 The Milky Way Galaxy
	16.1 Discovering the Milky Way
		Shape of the Milky Way
			Size of the Milky Way
	16.2 Overview of the Milky Way
		Content and Structure
			Mass of the Milky Way and the Number of Stars
			Age of the Milky Way
	16.3 Stars of the Milky Way
		Stellar Censuses
			Two Stellar Populations: Population I and Population II
			Star Clusters
	16.4 Gas and Dust in the Milky Way
		Distribution and Composition of Interstellar Matter
			Interstellar Dust: Dimming and Reddening
			Interstellar Gas
	16.5 Motion of Stars and Gas in the Milky Way
		Extending Our Reach: Mapping the Milky Way with Radio Waves
	16.6 Measuring the Milky Way
		Diameter of the Milky Way
			Mass of the Milky Way
		Extending Our Reach: Measuring the Mass of the Milky Way
	16.7 The Galactic Center
	16.8 Evolution of the Milky Way
		Birth of Population I and II Stars
			Evolution by Mergers
			Population III
			The Future of the Milky Way
			Projects
17 Galaxies
	17.1 Discovering Galaxies
		Early Observations of Galaxies
			Types of Galaxies
			Differences in the Stellar and Gas Content of Galaxies
			The Evolution of Galaxies: Collisions and Mergers
	17.2 Measuring the Properties of Galaxies
		Galaxy Distances
		Extending Our Reach: Measuring the Distance of a Galaxy Using Cepheid Variables
			The Redshift and the Hubble Law
			Measuring the Diameter of a Galaxy
		Extending Our Reach: Other Ways to Measure a Galaxy’s Distance
			Measuring the Mass of a Galaxy
	17.3 Dark Matter
		Science at Work: Dark Matter or Maybe Not
	17.4 Active Galaxies
		The Discovery of Nuclear Activity
			Quasars
			A Unified Model of Active Galaxies
		Extending Our Reach: Estimating the Diameter of Astronomical Objects by Using Their Light Variability
		Science at Work: Superluminal Jets
	17.5 Probing Intergalactic Space
		Quasar Absorption Lines
			Gravitational Lenses
	17.6 Galaxy Clusters
		The Local Group
			The Relationship of Cluster Size and Galaxy Type
			Superclusters
			Projects
18 Cosmology
	18.1 Observations of the Universe
		Distribution of Galaxies
			Motion of Galaxies
			Age of the Universe
		Extending Our Reach: Estimating the Age of the Universe
			Are We at the Center of the Universe?
	18.2 Looking Back Toward the Beginning of Time
		Olbers’ Paradox
			The Cosmic Horizon
			The Cosmic Microwave Background
			Composition of the Oldest Stars
			Deductions from Basic Observations of the Universe
	18.3 Evolution of the Universe: Expansion Forever or Recollapse?
		The Density of the Universe
			Dark Energy
	18.4 The Curvature of the Universe
		Science at Work: The Universe’s Fate
	18.5 The Origin of the Universe
		The Early Universe: Radiation, Matter, and Antimatter
			History of Matter and Radiation in the Early Universe
			The Formation of Galaxies
	18.6 The Inflationary Universe
		Extending Our Imagination: Other Universes?
			The Flatness Problem
			The Horizon Problem
			Project
ESSAY 4
	Life in the Universe
		Life on Earth
		The Unity of Living Beings
		Deductions from the Unity of Life and the Time Line
		The Origin of Life
		Origin of Complex Organisms
		Life Elsewhere in the Universe
		Searching for Life Elsewhere
		Panspermia
		Are We Alone?
		Arguments for Many Worlds
		Arguments That We Are Alone
		Radio Searches
		Life and the Transformation of Planets
		The Anthropic Principle
Answers to Test Yourself
Appendix
	Scientific Notation
	Some Useful Formulas
	Solving Distance, Velocity, Time (d, V, t ) Problems
	Table A.1 Physical and Astronomical Constants
	Table A.2 Conversion Between American and Metric Units
	Table A.3 Physical Properties of the Planets
	Table A.4 Orbital Properties of the Planets
	Table A.5 Satellites of the Solar System
	Table A.6 Properties of Some of the Solar System’s Dwarf Planets
	Table A.7 Meteor Showers
	Table A.8 The Brightest Stars
	Table A.9 The Nearest Stars
	Table A.10 Properties of Main-Sequence Stars
	Table A.11 Known and Suspected Members of the Local Group of Galaxies
	Table A.12 The Brightest Galaxies Beyond the Local Group
Glossary
Credits
Index