If you've always wanted to go to infinity and beyond, here's your chance. A free, real-time space simulation, Celestia lets you experience outer space in three dimensions. Unlike other planetarium software, the interactive program travels beyond our solar system, at any speed, at any moment in time and in any direction. If you like, use some of the Celestia add-ons (also available for free download) to watch Apollo 11 land on the moon in 1969, to visit the sweltering surface of Venus, to count the pulses of Crab Nebula, or to enjoy hundreds of other far-out adventures. Just follow the guidelines and go!