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.
The public beta of Worldwide telescope is now available at http://www.worldwidetelescope.org and get empowered to explore and understand the universe with its simple and powerful user interface.
Note that the WWT requires DirectX 9.0c even when you already have DirectX 10 installed on my Vista box. The reason is that DirectX has a subcomponent (D3DX) that gets revved more often than DX itself. So, when people ask for DX 9.0c, they really mean DX 9.0c and D3DX rev 35 (for example). That's why you keep seeing the DX installer over and over again when you install a new DX app.
Now that the revving of D3DX has slowed down, these installers should be further and fewer apart (you roughly get one install per rev of D3DX).