Google Earth now include the Milky Way.
Willard Staff: The YouTube video below will be blocked at school. It is worth the time to watch it elsewhere.
[kml_flashembed movie="http://www.youtube.com/v/eMhGpzyFdhE" width="425" height="350" wmode="transparent" /]
Google Earth is a bandwidth hog and must be used conservatively. It should not be run on multiple lab stations at one time. One suggestion from Google is to access the pages prior to the lesson and your computer will store some of the information in its cache. Then when you use Google Earth in your lesson, some of the data comes from your hard drive, as opposed to the Internet.