# General Astronomy

Astronomy is the scientific study of celestial bodies in the visible universe, from the scale of a few meters to the macro scale, including: the underlying physics governing those bodies, what they are made of, their properties, distribution, relation, distance, movement, creation, age and demise.
Our understanding of the universe has dramatically improved due to the progress of technology. Astronomy has been one of the most modernized areas of scientific study, but it is also one of the oldest sciences — practiced by all ancient civilizations to some degree. Sadly, people have increasingly started to lose connection with the observable universe, something that was previously even required for measuring time, and defining seasons. Astronomy is among our species' first technological steps, but today only passingly remarked about when it verifies something thought about in theoretical physics. Even in a highly industrialized global civilization, defined by consumerism only a few of us had the chance to go beyond simple images and concepts and have a practical experience in considering what is around our blue dot and its implications for us.
This Wikibook introduces the reader to that tapestry and the process that revealed it to humanity. It presents astronomy not only as a field of knowledge, but also as a human endeavor in science.

## Table of Contents

* The Modern View of the Cosmos
** The Big Picture
** Short History of the Universe
** Scientific Notation
** The Scientific Method
** What People do in Astronomy
** Current Unsolved Mysteries
* Observational Astronomy
** The Celestial Sphere
** Coordinate Systems
** Phases of the Moon
** Eclipses
** Daily Motions
** Yearly Motions
* Motion and Gravity
** The Early Origins of Astronomy
** The First Physics (Aristotle)
** Difficulties in the Geocentric Model
** The Heliocentric Model (Copernicus)
** New Ideas About Motion (Galileo)
** Order in Planetary Orbits
* Principles of Light
** What is Light?
** The Spectrum
** Basic Astrophysics
** Atomic Emission and Absorption
** Molecular Emission and Absorption
** Thermal Radiation
** The Doppler Effect
* Telescopes
** Basic Optics
** Optical Telescopes
** Telescopes of Other Wavelengths
** Neutrino Telescopes
** Gravitational Wave Telescopes
** Other Observations
* Planetary science
** The Terrestrial Planets
** The Jovian Planets
** Planetary Moons
** Comets
** Asteroids
** Meteors and Meteorites
** The Kuiper Belt
** Extrasolar Planets
** Formation of the Solar System
* Earth as a Planet
** Earth's Early Years
** Formation of the Moon
** The Biosphere
** The Atmosphere
** The Water Cycle
** Earth
** Earth's Moon
* Space Exploration
** First Steps into Space
** The Apollo Missions
** Pioneers and Voyagers
** The Great Observatories
** Major Future Missions
* Astrobiology and Extraterrestrial Life
** The Drake Equation
** Organic Chemistry for Astronomy
** Life in the Solar System
** The Search for Extraterrestrial Intelligence
* The Sun
** Fusion in the Sun
** Convective and Radiative Zones
** The Photosphere
** Solar Activity
** Space Weather
** Helioseismology
** The Solar Cycle
* Stars
** Mass
** Luminosity
** Temperature
** The H-R Diagram
** Star Clusters as Cosmic Laboratories
* The Stellar Life Cycle
** Protostars and Stellar Nurseries
** The Life of Low Mass Stars
** The Death of Low Mass Stars
** The Life of High Mass Stars
** The Death of High Mass Stars
* Black Holes
** Life of the Black Hole
** Black Holes in Hiding
** History of the Black Hole
** The Theory of the Naked Singularity
** Spaghettification
** Black Holes/Hawking Radiation
* Galaxies
** The Milky Way
** Types of Galaxies
** Galactic Formation
** Galactic Evolution
** Supermassive Black Holes
** Active Galactic Nuclei and Quasars
* Gamma-Ray Bursts and Cosmic Rays
** Introduction and Brief History of Gamma-Ray Bursts
** Long-Soft and Short-Hard Classifications
** Fluence and Extragalactic Nature
** Sources of Gamma-Ray Bursts
** Lingering Mysteries
* Cosmology
** The Distance Ladder
** The Big Bang and Cosmic Expansion
** The First Three Minutes
** Higgs Boson
** An Accelerating Universe
    References
    Exercises

## Also on Wikimedia

Wikibooks is a Web site where this and other free textbooks are developed. In addition to this book, Wikibooks is the host of related textbook projects.
* General Relativity, an advanced undergraduate treatment of the principles of general relativity
* Astrophysics, a textbook for beginning students in physics and astronomy
* Astrodynamics, a look at the principles behind orbiting satellites
* Wikijunior:Solar System, a children's nonfiction book about the Solar System
* Messier Index, a list of all the deep-sky objects in the Messier Index.