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...

This Topic in Depth presents the science and research of galaxies. First, the University of Cambridge offers clear, logical descriptions and images of the Milky Way, spiral and elliptical galaxies, clusters, and dark matter of the Universe (1). Users can also find educational tutorials on many other cosmology topics. Next, the Space Telescope Science Institute's "Galaxies Galore, Games and More is...

The Space Science Telescope Institute and National Aeronautics and Space Administration have made this resource available. NASA's Hubble Telescope has photographed the results of the collision of the Antennae galaxies: the eruption of over a thousand bright young star clusters. At this site users can view a number of striking images in a variety of resolutions. The official press release and fact...

This site is a companion to the travelling Space Telescope Science Institute (STScI) and Smithsonian exhibition. Offerings include numerous brief, illustrated fact sheets on the telescope and the universe, movies, related links, and information on the travelling exhibit. This modest but well-crafted site offers a nice educational diversion for anyone interested in astronomy.

The Hubble Telescope's "deepest-ever view of the universe" is available for viewing. "Several hundred never before seen galaxies are visible in this 'deepest-ever' view of the universe, called the Hubble Deep Field (HDF), made with NASA's Hubble Space Telescope. Besides the classical spiral and elliptical shaped galaxies, there is a bewildering variety of other galaxy shapes and colors that are...