These websites take a scientific perspective to astrolomy and the planets. They provide valuable information about planetary cycles and movements, as well as just some cool information.
The secrets of ancient calendars. A very cool website that combines astronomy and Pagan holidays, providing extremely precise dates and times for each. Some excellent animation, graphics and videos that illustrate the mechanics of the Equinoxes, Solstices and other celestial phenomena. "Archaeoastronomy" is a relatively new field that studies the astronomy and calendars of the prehistoric ancients.
"Does anybody really know what time it is?" Now you can find out. Good reference site for astrologers.
The focus of this site is astronomy (the scientific facts) not astrology (the meaningful interpretation of those facts), but it's a great reference site to understand the mechanics behind eclipses.
NASA's Astronomy Pic of the Day website, which posts amazing and fascinating pictures of astronomical phenomena daily, from planets, stars, nebulae and galaxies to aurora borealis and weather spectacles.
This website gives a lot of information on the real story about "Blue Moons" -- not what you think! And be sure you read my own article on Blue Moon Lunacy.
Be part of the Search for Extraterrestrial Intelligence! (SETI) SETI@Home is now being run through the BOINC platform (Berkeley Open Infrastructure for Network Computing), which also connects to various other volunteer computer-grid projects for astronomy and medical research.
Shadow and Substance (added February 2008)
If you're looking for detailed animation and fabulous diagrams of things like eclipses, comets, planetary orbits and other astronomical events, check this site out! Some of the best illustrations I've ever seen.
Time and Date.com (added April 2007)
Another excellent site to tell you what time it is anywhere in the world! You can create a personalized page with the current times of specific places that you choose. This is a great resource if you have to arrange meetings with people in other time zones. (I found this out the hard way. LOL)
The World At Night (added February 2008)
Stunning photographs of night scenes around the world! The World At Night (TWAN) is a project coordinated by Astronomers Without Borders, an organisation created to promote world peace through our common reference of the sky. ("One People, One Sky.") The TWAN website is a showcase of some of the most beautiful pictures and videos of night-time scenes on our planet that you will ever hope to see. Modern astrology is so often reduced to numbers, symbols and charts, but on this site you can see pictures of the very things we record in our astrology charts. Makes you feel like one of the Ancients as they stood inspired and awed by the starry starry night.