Watch and Explore Outer Space with Stellarium, Celestia, and Xplanet

“Ubuntu founder Mark Shuttleworth spent about $20 million to go
into space, and he never got farther away from Earth than a few
hundred miles. Using three free software programs, you can look at
and virtually travel to places millions of miles away without
leaving your GNU/Linux desktop or paying a dime.

“The GNU GPL covers all three programs, and most major
distributions include all of them as packages…”