celestia: celestia - a real-time space simulation
celestia: 
celestia: Unlike most planetarium software, Celestia doesn't confine you to the
celestia: surface of the Earth. You can travel throughout the solar system, to
celestia: any of over 100,000 stars, or even beyond the galaxy.
celestia: All movement in Celestia is seamless; the exponential zoom feature
celestia: lets you explore space across a huge range of scales, from galaxy
celestia: clusters down to spacecraft only a few meters across.
celestia: Celestia is expandable. Celestia comes with a large catalog of stars,
celestia: galaxies, planets, moons, asteroids, comets, and spacecraft. If that's
celestia: not enough, you can download easy to install addons with more objects.