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Derived from the Greek term, meaning “star law”, astronomy is the scientific study of all celestial objects and the universe as a whole. There are two general branches of astronomy including optical astronomy and non-optical astronomy. Optical astronomy is the specific study of all celestial bodies in the visible band. Non-optical astronomy is the practice of studying celestial bodies through radio via gamma-ray wavelengths. This branch of science studies the various motions and chemical properties of the objects found outside of earth’s atmosphere, such as the planets, galaxies, and stars. Below you will learn more information about the categories included in the study of astronomy.

General Astronomy

• American Astronomical Society: Basic information about the Solar System, including stories about the planets, the Milky Way, including information on our galaxy and the names of stars, and the Universe as a whole, including details about the Big Bang theory.
• General Physics of Astronomy: Learn about the connection between physics and astronomy first founded in the 17^th Century by Isaac Newton when he reasoned that gravity was the reason for which objects were pulled to earth and planets orbited around the sun.
• Frequently Asked Questions: Find the answers to your general astronomy questions, such as “Do all objects in the universe exert force on all other objects?” and “Do the orbits of any of our planets change, or do the planets always follow the same paths?”
• Astronomy Magazine Experts: Tour the Solar System with a series of videos and articles, including the Sun, Earth, Mercury, and Comet 103P/Hartley which promises to be the brightest comet of 2010 when it comes forth in October.

History of Astronomy

• Center for Astrophysics & Space Sciences: Brief history of astronomy including information on the astronomical site Stonehenge, constructed between 3100-2000 BCE, as well as the guest star known as Comet Halley which can be traced back to 240 BCE.

Astronomy and the Scientific Revolution

• Timeline of the Scientific Revolution: Beginning in 1473 with the birth of Copernicus, this timeline of the scientific revolution guides you through nearly 300 years of important events in astronomy until Newton’s death in 1727.
• Beginning of the Scientific Revolution: Find information on the start of the scientific revolution when the only known planets were Mercury, Venus, Mars, Jupiter, and Saturn. The Sun and Moon were added shortly there after, as they were thought to revolve around the earth.

Astrometry and Celestial Mechanics

• Celestial Mechanics & Astronomy: Learn about the three main branches of astronomy, astrometry, celestial mechanics, and astrophysics. Astrometry is the oldest branches of astronomy, created to map the positions of “fixed” stars.
• Particle Physics: Find a description of celestial mechanics and how the positions of the Sun, Moon, and each of the planets and stars have their own space that is essential for celestial navigation.

Gamma-Ray Astronomy

• NASA Goddard Space Flight Center: Read through two levels of astronomy science topics, including information on the history of gamma-ray astronomy, observing platforms, and targets of gamma-ray observations.
• High Energy Astrophysics: General information on gamma-ray astrophysics, as well as photographs of Cassiopeia A, a 340 year old supernova and the EGRET instrument used to make a number of discoveries, including pulsars and high energy emission from blazers.
• Very High Energy Gamma-Ray Astronomy: Learn about the Imaging Atmospheric Cherenkov Technique and the construction of the Very Energetic Radiation Imaging Telescope Array, or VERITAS.
• Gamma-Ray Astronomy: Descriptions of the various aspects of gamma-ray astronomy, including gamma-ray lines, cosmic-rays produced gamma-rays, gamma-ray bursts, AGN, and microquasars.

Infrared Astronomy

• Infrared Astronomy Tutorial: View new images taken from the Spitzer Space Telescope, as well as information on the discovery of infrared, the infrared universe, infrared spectroscopy, and the IR astronomy timeline.
• IR Astronomy Overview: Description of infrared astronomy as well as images take from the central region of the Milky Way Galaxy and the Cygnus star-forming region. Learn how the use of infrared can help astronomers develop information about the universe.
• SOFIA Science Center: Created and operated by the Universities Space Research Association (USRA) and the Deusches SOFIA Institute (DSI) for NASA, find information on observatory preparations for science flights.

Observational Astronomy

• Amateur Observational Astronomy: Find information about the five major types of amateur observational astronomy. These include observing with your unaided eyes (without optical aids), binoculars, telescopes, cameras (that use electronic technologies), and astronomical spectroscopy.
• Methods of Observational Astronomy: Basic introduction to the use of telescopes and information on measuring the distance to stars. Other information on this website includes modern views of Mars and the Universe endgame.
• Department of Physics and Astronomy: Learn about the X-ray and Observational Astronomy Group (XROA) and what they do to earn the title of the world’s leaders in high energy and observational astrophysics.
• Observational Astronomy Experiments: Fulfill these experiments of examining and photographing the sky with the naked-eye to spot the path of the sun as it crosses the sky and how the stars form patterns.

Optical Astronomy

• National Optical Astronomy Observatory: Find news and reports from NOAO and an image gallery that includes photographs of astronomical objects, such as the galaxies (elliptical and spiral), nebulae (absorption, emission, planetary, and reflection), the Sun, the Solar System, and stars.
• Optical Astronomy and Radio Astronomy: Descriptions of optical astronomy and radio astronomy, as well as limitations and advantages of each of these forms of observational astronomy.

Radio Astronomy

• Frequently Asked Questions: Find answers to frequently asked questions about radio astronomy, such as “How is radio astronomy different from optical astronomy?” and “What is a radio-telescope?”
• National Radio Astronomy Observatory: Information on the study of radio astronomy, electromagnetic radiation, and electromagnetic spectrum. Explore and download quality images of the universe.
• Basics of Radio Astronomy: Download a fact sheet on radio astronomy or read through information on the Goldstone-Apple Valley radio telescope or basic information on the Earth, Solar System, galaxies, and stars.
• Radio Astronomy Learning Guide: Description of radio astronomy and how it’s a relatively new form of science compared to optical astronomy. Download a free pdf document of the Radio Astronomy Learning Guide.

Theoretical Astronomy

• Theoretical Astrophysics Group: Find a description of what operations the Theoretical Astrophysics Group performs and what research areas are concentrated on, including the dynamical evolution of accretion discs.
• Institute of Theoretical Astronomy: Learn about the Virginia Institute of Theoretical Astronomy founded in 1985. Click on one of several information boxes to learn more about the supernovae and other areas of VITA.
• Theoretical Astrophysics and Plasma Physics: Guides to a summary of cosmos in the solar systems, galaxies, stars and universe. Find information on asteroids, stars and their environment, galaxy classification, and dark matter.

Ultraviolet Astronomy

• Introduction to Ultraviolet Astronomy: Read through several categories included in ultraviolet astronomy, including UV bands, motivation for UV observations, missions, UV instrumentation, and UV detectors. 
• Far-Ultraviolet Astronomy: Learn about ultraviolet astronomy from the Astro-1 space shuttle mission, far-ultraviolet spectroscopy, and the Hopkins Ultraviolet Telescope and its scientific results.
• Astro Guide to Ultraviolet Astronomy: Find images of galaxies and stars, as well as information on radio programs. Some of these include Moon and Jupiter, Rigel, Moon and Spica, Big Eruption, and Double Giant.

X-Ray Astronomy

• Introduction to X-ray Astronomy: Find answers to your questions about X-ray astronomy, such as “What is X-ray astronomy and how do we do it?” as well as information on the history of X-ray astronomy.
• X-ray Vision: This website presents information on x-ray astronomy, the Chandra scope, black holes, dark matter, and neutron stars. Also find information on what astrophysicists’ do: scientists who analyze physics experiments in space that can not be performed on earth.
• The Chandra X-ray Observatory Center: Learn where Chandra is located at this very moment, as well as information on the Chandra mission. Look through the photo gallery of images of Chandra from 1999 to current date.