Celestia is a free, open-source space simulation that lets you explore the universe in three dimensions. Unlike planetarium software that shows the sky from Earth, Celestia lets you travel through the solar system and beyond, visiting planets, moons, asteroids, and stars.
The solar system model includes all major planets and their moons with accurate positions, orbits, and rotations. Surface textures show planetary features in detail. Ring systems display correctly around Saturn, Uranus, Neptune, and Jupiter. Spacecraft and probe models mark historic missions.
The star catalog includes over 100,000 real stars with accurate positions, distances, spectral types, and proper motions. Travel to any star instantly or at defined speeds. Star labels help identify objects. The Milky Way provides accurate structure for our galaxy.
Time controls enable viewing celestial events at any point in history or future. Watch planetary conjunctions, eclipses, and comet approaches. Accelerate time to see orbital motions unfold. Lock view to objects to follow their movement through space.
Scripting with Cel and Lua languages creates guided tours and educational presentations. Record flythrough videos for sharing. Educational add-ons provide additional content about astronomical objects. The observing location can be set anywhere for understanding different perspectives.
Add-on content extends Celestia with additional textures, spacecraft, stars, and even fictional objects. The active community has created extensive supplementary materials.