Name: Celestia

Platform: Windows, Mac, Linux

Download Link: celestia.space

Description:
Celestia is a space simulation that lets users explore outer-space in 3D. The program is setup to make the user feel like they are piloting a real star ship. Students can a trip in our solar system or out to over 100,000 stars and other galaxies. Celestia has a 'point-and-goto' user interface that makes simple navigation through the heavens. Celestia includes stars, galaxies, planets, moons, asteroids, comets, and spacecraft. There are over 15 gigabytes of add-ons available at its website.