Google Earth is a downloadable satellite imagery-based view of the earth from space to street level, that can be used by teachers and students in their studies of geography, the earth, economics, demographics and transportation. It can be added to your iGoogle page. The newest feature of Google Earth, Sky, lets student view galaxies, stars and planets. Teachers, see examples of how to use it in the classroom.
A web-based version of Google Earth for Chrome browsers is now available. The app is also available for iPad/iPhone and Android devices. Note that it runs best on most recent smartphones with memory upgrades.