The latest version of Google Earth now includes maps of the stars. Thanks to help from NASA and the Space Telescope Institute Google 'sky' covers around a hundred million stars and over two hundred million galaxies. Just as you can use Google Earth to randomly browse a map you can use Sky to explore space like never before; additionally Google Sky can be used as an aid to would-be star gazers. By default a user will be shown the sky as seen above their current location in Google Earth. This can be great for identifying constellations visible in the night sky around you. Layers can be added or removed--these include constellations and images from the Hubble telescope with accompanying data-sheets.
One particularly nice feature of the planets layer is that the planet's orbits can be animated using a time slider. Pre built tours are available which include some of the most stunning pictures of space I have ever come across, I particularly enjoyed STScl's best of Hubble tour.
This new addition to Google's growing arsenal of killer apps is definitely great fun. If you haven't already then take a look for yourself but be careful, you may find yourself lost in space for hours!