The earth's diameter is 12,756.3 km and its revolution period is 1 year. You probably knew the last fact, but most likely not the first. The Web site Absolutely Astronomy can provide this and a large amount of other facts about planets, moons, stars, constellations, messier objects, nebulas, and galaxies. Visitors can browse via the pull-down menus or search by a particular question. The basic...

Both beginning and seasoned amateur astronomers, as well as casual stargazers, may find this Astronomy Reference Guide from Sea and Sky to be a helpful resource. Here, visitors will find a plethora of information to help budding astronomers get started, such as an extensive FAQ page covering the basics of various celestial bodies and astronomy in general, as well as a glossary of astronomical...

With the advent and proliferation of the Internet and Web access, a multitude of information has become immediately accessible to anyone with a computer and a phone line. Providing home-spun wisdom and advice has been a hallmark of The Old Farmers Almanac since 1792, and their site features quite a bit of free information that will be useful to new visitors and familiar to long-time fans of the...

One of many educational pages devised by entrepreneur and programmer John Walker, YourSky is a virtual planetarium. Visitors to the site can use the Sky Map to produce astronomical maps by entering time and date, viewpoint, and observing location (latitude/longitude and ascension/declination). The Virtual Telescope helps you to track comets and asteroids, and Horizon Views returns views of the...