Online Astronomy Text Table of Contents
Recent Updates / Recent Pictures / Recent Questions and Replies
© Courtney Seligman, 1993-2013
(This eText and its Table of Contents are a work in progress)

Section Links
Background Physics: Motions and Forces / Light and Matter
Looking at The Sky / The Rotation of the Planets / Orbital Motions
Planets / Satellites (Moons) / Asteroids and Comets / Origin of the Solar System
The Sun / Stars and Stellar Systems / Stellar Evolution
Galaxies and the Universe / Appendices

Introduction to this eText
Preface (the purpose of this text, and its use in my classes)
The Use of Mathematics In My Lecture Classes (if you enjoy math, great; if not, don't worry about it)
False Colors in Astronomical Photographs (pictures may not lie, but they can still mislead)

Introduction to Astronomy
Our Place In Space (introduction to the Solar System)
The Realm of the Stars (introduction to extrasolar astronomy)

Looking at The Sky
The Starry Sky

Nightfall (a dark and starry night)
Stars and Constellations (dividing the sky into manageable pieces)
The (Northern) Milky Way / The Arc of the Milky Way
Star Names / Name That Star -- Not! (how stars are named, or not)
Atmospheric Effects
Why Stars Twinkle
Atmospheric Refraction (how the atmosphere bends starlight)
Atmospheric Dispersion (how the atmosphere acts like a prism)
Atmospheric Scattering (why the sky is blue, and the setting Sun is red)
The Dome of the Sky
The Celestial Sphere (the apparent globe of the sky)
The Moon Illusion (why the Moon looks bigger, when rising or setting)
Astronomical Coordinates (measuring positions on the celestial sphere)
The PZS Triangle (placeholder)
The Motion of the Sky (that is, of the "fixed" stars)
Parallax -- (background geometry, critical to many parts of astronomy)
The Motion of the Sky (a general introduction) / Polar Animation
The Motion of the Sky at Different Latitudes (at the Poles, the Equator, and mid-latitudes)
Stars Setting at the Equator (a larger image)
The Many Motions of the Stars (placeholder and link to other pages)
The Wanderers (introduction to non-stellar (or planetary motions)
The Wanderers (introduction) / Today's Positions of the Sun and Planets
The Motion of the Moon (around the sky in a moonth)
The Motion of the Sun (around the sky in a year)
The Changing Motion of the Sun (faster and slower)
The Motion of the Planets
Phases and Eclipses
The Phases of the Moon
Eclipses / Lunar Eclipses / Solar Eclipses
Timekeeping and the Calendar
Timekeeping (sidereal, solar, and ephemeris time)
The Calendar (why we count the days the way we do)

The Rotation of the Planets
The Rotation of the Earth
The Rotation of the Earth / Day and Night / Climatic Zones / Coriolis Effects
Rotation Period and Day Length
Rotation of the Other Planets
Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto
The Seasons
The Seasons
Seasons on the Other Planets (tilt diagram)
Planetary Temperature Factors

Background Physics: Motion and Forces
Notes on Motion / Newton's Laws of Motion  /  Inertial & Non-Inertial Reference Frames  /  Fictitious Forces
A Matter of Some Gravity  /  Lagrange Points
Gravitational Interactions of the Earth and Moon: Barycentric Motion / Tides / Precession
Orbital Perturbations and Gravitational Assists

Orbital Motions
Planetary Orbits (also see Orbital Regularities)
The Ptolemaic Cosmos / The Copernican Revolution
Planetary Aspects / Retrograde Motion  /  Transits of Mercury and Venus
Tycho Brahe's Astronomical Accomplishments / Biography of Tycho Brahe
Kepler / Galileo / The Phases of Venus  /  The Discovery of Planet Earth / Galilean Relativity
Ellipses and Other Conic Sections
Kepler's Laws of Planetary Motion / Kepler's First Law / Kepler's Second Law / Kepler's Third Law
Cassini Measures the Orbit of the Sun / Bradley's Discovery of Stellar Aberration
Orbital Effects on Planetary Weather

Planetary Data Table / Printable (PDF) Version of Table / Using the Planetary Data Table
Understanding Planetary Interiors
The Structure of the Terrestrial Planets / The Structure of the Jovian Planets
Internal Pressures of the Planets / Accurately Calculating Internal Pressures
The Internal Temperatures and Magnetic Fields of the Planets / Metallic Hydrogen (brief notes)

Understanding Planetary Atmospheres
The Structure of Planetary Atmospheres / The "Surfaces" of the Jovian Planets
Atmospheric Effects on Planetary Temperatures
The Retention/Loss of Planetary Atmospheres (Incomplete)

Satellites (Moons)
Asteroids, Comets, and Interplanetary Debris
Pictures of Asteroids / Asteroid Size and Mass Distribution / Asteroids and Meteorites
Asteroids & Comets Visited So Far / Ceres and Vesta / The Trojan Asteroids / Earth's Trojan Asteroid(s)
The Rediscovery of Hermes / Hermes Close Approaches
Comets / The Breakup of Comet P73/Schwassmann-Wachmann 3 / Comet P17/Holmes
Meteors, Meteoroids and Meteorites / Animation of the 2005 Perseid Meteor Shower / Meteor Craters / Meteorites

The Origin and Evolution of The Solar System
The Origin of the Solar System / The Episode of Planetary Bombardment / Orbital Regularities
The Origin of the Comets
The Origin of the Moon
The Melting and Differentiation of the Planets
The Formation and Evolution of Planetary Atmospheres

Background Physics: Light and Matter
Classical Descriptions of Light /
Electromagnetism / Absorption, Emission, and Continuous Spectra / Black Body Radiation
Planck, Bohr and Einstein -- Quantum Physics and Relativity
Radioactivity / Thermonuclear Fusion / Main and Side Chains / Neutrinos

The Sun
Summary of Solar Properties
Pictures of the Solar Atmosphere / The Sunspot Cycle / Coronal Mass Ejections / The Heliosphere
The Rotation of the Sun / Extreme Ultraviolet Images of the Sun
The Solar Atmosphere and Surface

The Solar Interior
Heat Flow in the Solar Interior: Changes in Brightness, Temperature, Pressure and Density
Energy Production in the Core / The Proton-Proton Cycle (brief notes) / The Carbon Cycle (brief notes)
Heat Flow in the Solar Interior: The Flow of Radiation / The Radiative Zone
Black Body Radiation
Heat Flow In Stars: General Principles / The Radiative Core (Zone) / The Convective Envelope (Zone)

Stars and Stellar Systems
Stellar Properties (includes The Hertzsprung-Russell Diagram)
Stellar Motions
The Changeable Constellations
Proper Motion
Radial Velocities
Variable Stars -- Cepheid Variables / Variable Stars -- Epsilon Aurigae
Open ("Galactic") Star Clusters / Globular Clusters
Emission Nebulae / Absorption Nebulae
Stellar Birthplaces ("smaller" links below are mostly works in progress)
The Rosette Nebula / The Eagle Nebula (IC 4703) / Protoplanetary Disks in the Orion Nebula
The Tarantula Nebula and R136 / The Carina Nebula
Supernovae and Supernova Remnants

Stellar Evolution

Galaxies and The Universe
Our Galaxy and Its Satellites / The Milky Way
The Local Group / The Andromeda Galaxy / Detail of M31 by the Subaru Telescope
M81 and M82: A Cosmic Near Miss
Pictures of Other Galaxies / M104, The Sombrero Galaxy / NGC 55 / NGC 7252
Clusters of Galaxies / Abell 1689, A Massive Gravitational Lens
The Universe of Galaxies / The M31 Deep Field / GOODS Fornax Deep Image / Whole-Sky Maps of the Universe
Dark Matter in Galaxies / Dark Matter in the Universe
The Expansion of the Universe / The Observable Universe / In The Beginning
Light-Travel Times and Cosmic Distances

Glossary (A - M)  /  Glossary (N - Z)
Astronomical and Physical "Constants" / Picky, Picky
Sky Atlas
List of Constellations
Charles Messier's Catalog: Nebulae / Open Clusters / Globular Clusters / Galaxies / Messier Catalog Index
Arp Atlas of Peculiar Galaxies
Introduction to the NGC / IC / PGC Objects Pages / NGC Objects / IC Objects / PGC Objects
The Discoverers of the NGC / IC Objects