And now, Google Sky™!
The latest version (4.2) of Google Earth™ now has a non-descript button on the tool bar that when clicked on, turns the view around from facing good old mother Earth to looking at the stars!
Google Sky™ uses images from the Hubble Telescope, the Sloan Digital Sky Survey (SDSS), NASA images, and the DSS Consortium to tell the story of the sky.
Just as Google Earth™ has incorporated stories from National Geographic, images from the Rumsey Historic Map Collection, and trails from Backpacker Magazine to name a few, Google Sky™ uses the same technique to incorporate a series of layers that currently includes Constellations, Backyard Astronomy, Hubble Showcase, The Moon, The Planets, a User's Guide to Galaxies, and the Life of a Star. Each of the Google Sky™ layers has an introduction that explains the contents of the layer, and how they can be used.
Science teachers will find these aspects quite supportive when teaching students about what's going on in the night sky. By clicking on a button, students can watch the movement of the planets in the night sky over a three month period, especially useful when teaching the concept of retrograde motion of the planets. The Constellations layer provides locations as well as outlines of both major and minor constellations. Just as in Google Earth™, teachers, as well as students, can create "tours" of the night sky by using a series of placemarks.
The User's Guide to the Galaxies is a true showcase of a collection of images from the Hubble telescope. It incorporates images and details about the different types of galaxies. Many of the image windows include links to Wikipedia providing additional information about the discovery and formation of specific galaxies. Many of the named objects include a link to the NASA/IPAC Extragalactic Database, which students can use for further study.
The latest version of Google Earth™ that includes the link to Google Sky™ is currently downloadable free of charge from the Google Earth website: http://earth.google.com/