The WorldWide Telescope (WWT) is a Web 2.0 visualization software environment that enables your computer to function as a virtual telescope—bringing together imagery from the best ground and space-based telescopes in the world for a seamless exploration of the universe.

This is a really neat program. It lets you choose different types of imagery too, for example, to view infrared or ultraviolet wavelengths, and also the cosmic background radiation.

Download:
http://www.worldwidetelescope.org/experien...perienceIt.aspx