http://www.worldwidetelescope.org/Home.aspx
Microsoft's answer to Google Earth: WorldWide Telescope. I had this installed last year on my second laptop but I didn't keep up with it after my laptop woes (second got destroyed, third one was hardware-faulty, now I'm on my fourth), but now that I installed the latest WorldWide Telescope, I'm amazed by how updated it got.
If anyone is interested in learning more about outerspace, try this software (and it's free
).











But it's like Microsoft is saying, "Google, you do the Earth while we do the cosmos."