Astronomy Picture of the Day
NASA provides this page, which posts a new image or photograph daily. An explanation of the scientific importance of the image, provided by a professional astronomer, is given as well.

Astro Web
This directory lists web pages relating to astronomy and astrophysics, including many research sites. To search, click on "Search," which is directly under the logo. The site is maintained by STScI (the Space Telescope Science Institute).

EducationIndex
The Education Index lists quality education-related sites on the Web. Sites are listed in two ways; the first is by subject, which is the link provided here (check out Physics and Astronomy), and the second is by life-stage. We recommend browsing through the subjects - partly, it's just loads of fun to check out the "Web Weasel" participating in the various disciplines. Education Index is authored and maintained by Hobsons, an international college and career publisher.

Expanding Universe
A directory of amateur astronomy sites based on the Dewey Decimal classification system, this site was designed by the Toronto Reference Library.

The Internet Public Library
Presented by the School of Information at the University of Michigan, the IPL provides access to various information resources by subject area. Select the Science & Tech Category - the Physics or Astronomy Subcategory, then select subject headings or search keywords based on your area of interest.

The Particle Adventure
Take an interactive tour of elementary particles, and learn about the fundamentals of matter and force, courtesy of the Particle Data Group at the Lawrence Berkeley Laboratory.

PSIgate
Physical Science Information Gateway is a directory of web resources for the physical sciences, including chemistry, physics, astronomy, earth sciences and history of science.

Virtual Library: Physics
A gateway to important sites in physics, the Virtual Library includes links to sites on acoustics, astronomy & astrophysics, nuclear physics, high energy physics, and horology (timekeeping & clocks).

American Association of Variable star Observers: AAVSO
AAVSO (founded in 1911 at Harvard College Observatory) is a non-profit worldwide scientific and educational organization of amateur and professional astronomers interested in variable stars and what those stars can teach us.

The Anglo-Australian Observatory
A collaborative effort between British and Australian governments, "[t]he AAO operates the Anglo-Australian and UK Schmidt telescopes on behalf of the astronomical communities of Australia and the UK."

Peoria Astronomical Society
Presented by an amateur astronomy group, this site is a great source of information on topics like how stars get named, alignment while viewing the sky, recording data, methods that measure time in astronomy, pronunciation of constellation and major star names, and astronomical data.

Royal Observatory Greenwich
The ROG is the observatory keeping official "Greenwich Mean Time."

Sky & Telescope Resources - Clubs & Organizations
Excellent directory of astronomy-related organizations and institutions. This site provides up-to-date information about nearly 3,000 museums, planetariums, observatories, astronomy clubs, and societies throughout the United States, Canada, Mexico, Europe, Australia, New Zealand, and other countries. Maintained by the publishers of Sky & Telescope magazine.

Catalog of U.S. Government Science and Technology Web Site Resources
Maintained by the U.S. Dept. of Commerce and the National Technical Information Service, this site lists science-related web sites of government agencies. It is incomplete and sites are always being added, but there are a substantial number of sites already available. See the Astronomy & Space and Math, Physics & Chemistry sections under "Browse by topic."

National Aeronautics and Space Administration (NASA)
Everything you ever wanted to know about NASA projects, history, research opportunities, and more can be found at the official NASA site.  Photos from current and past missions are also available.

National Science Foundation
The National Science Foundation, or NSF, is and independent U.S. government agency responsible for promoting science and engineering through programs supporting research and education projects. See the program area of Math, Physical Sciences for information on relevant NSF-funded projects.