1. A real-time visual space simulation Celestia is a real-time visual simulation of space. Choose a point within the Local Group of galaxies, and Celestia will show you an approximation of how it would appear to your eyes were you actually there. Some of what Celestia shows is necessarily hypothetical--the farther away from Earth you get, the less real data there is and the more guesswork is involved. Thus Celestia supplements observational data with good guesses based on models of stellar and planetary processes. Celestia is unique in its ability to allow you to navigate at an immense range of scales. Orbit a couple kilometers above the surface of a tiny, irregular asteroid, then head off toward Jupiter, watching it grow from a bright point of light into a looming sphere filling your field of vision. Leave our solar system entirely and observe the sun as it fades from a brilliant disk to a bright star, disappearing almost entirely as you head off toward the Upsilon Andromeda system to orbit around its innermost giant planet. From Debian 3.0r0 APT