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.
Stellarium lets you watch the night sky, learn about the stars, and find constellations without going outside or even waiting for dark. Stellarium won the SourceForge.net Project of the Month Award in May 2006, and Digitalis Education Solutions, Inc, uses Stellarium in portable planetarium projectors that sell for as much as $41,100.
Stellarium comes with data to display more than 300,000 planets, stars, and other astronomical light sources, and from Stellarium's download page you get data to display even more stars.