In August 2007 Google added an interactive Google Sky element to Google Earth. This update to the program allows you to switch from Earth mode to Sky mode by selecting View>View Sky. In Google Sky mode you to get up-close and personal with over 100 million galaxies and 200 million stars. As Google did with Google Earth, Google Sky is made up of stitched photographs of the heavens pieced together to make a one giant navigable database of the universe.
Note: If you already have Google Earth installed, you can go here for the update to add Google Sky. Otherwise click Download now on this page for the complete, and latest, version of Google Earth, which includes Google Sky.