With permission from Chris Laurel, its primary author, the official Celestia Web site has been transferred to http://celestiaproject.net/

The new site is being run by a Celestia enthusiast in Russia and includes a Web Forum at
http://celestiaproject.net/forum/

Celestia is a free 3D astronomical visualization program which runs under Windows, MacOS and Linux. It's relatively easy to extend. Many Addons have been created to illustrate astronomy and spaceflight. See http://celestiamotherlode.net/ for some examples.

Does this mean development on Celestia will continue?

That is currently unknown. If it does, it probably won't involve many of the original programmers.