The latest version of Google Earth now also has Google Sky. Which allows you to zoom around the stars. There is also blue dots, which when clicked on open up a photo taken by the Hubble telescope.
http://earth.google.com/download-earth.html
The grandson loves it, he has books upon books about astronomy.
It also has an Easter Egg (that's a program withing a program)
http://googlesystem.blogspot.com/2007/0 ... light.html
It's supposed to be accessed with Ctrl+Alt+A but this didn't work for me but Ctrl+A did.
It's a flight simulator allowing you to fly round the world, or in my case till I crash it!! Took off from Heathrow and crashed in the Thames

Thanks Polter - we have a friend who will love that.
He has several of those programs where you are flying the planes.

I'll check it out later Polter