Has anyone used this free application?
Celestia is a Planetarium like software on a universe sized scale. You can explore planets, solar systems and whole constilations and nebela seemlessly.
http://www.shatters.net/celestia/
The official download links for the latest version 1.6 appear to be down from sourceforge.net at the moment, but luckily some others are hosting temporary mirror download sites to file the gap.
http://full2down.com/softwares/2612-celestia-160.html