Celestia is a free real-time space simulation that lets you experience our universe in three dimensions. Unlike most planetarium software, Celestia doesn’t confine you to the surface of the Earth. You can travel throughout the solar system, to any of over 100,000 stars, or even beyond the galaxy. All travel in Celestia is seamless; the exponential zoom feature lets you explore space across a huge range of scales, from galaxy clusters down to spacecraft only a few meters across. A ‘point-and-goto’ interface makes it simple to navigate through the universe to the object you want to visit. Celestia comes with a large catalog of stars, planets, moons, asteroids, comets, and spacecraft. If that’s not enough, you can download dozens of easy to install add-ons with more objects.
Pros: Celestia has excellent graphics, it’s faster and more responsive than most real-time space simulations, and the free-form navigation is a unique and welcome addition. Full documentation for Celestia is available at its website. Celestia is a cross-platform application for Mac, Windows, and Linux.
Cons: None significant.