Sky in Google Earth: click on the Sky button and the program transforms itself from an earth viewer to stargazing software, with multiple layers of astronomical information — planets, stars, constellations, Messier and NGC catalogues. I like the detail: I can click on a star and get all sorts of information about it (but the distance in light years in the Wikipedia entry excerpt doesn’t always agree with what’s listed elsewhere in the popup window), and the imagery is quite impressive once you zoom in. Just like the regular mode of Google Earth, you’re not just getting mapping data, you’re getting high-resolution imagery of deep-space objects. This is very neat.
Here’s a video from Google:
Frank has a video tutorial as well.
Bad Astronomy isn’t impressed: “Google Sky needs work. It’s more of a gee-whiz photo album than a real piece of interactive software.” In some ways it doesn’t compare favourably, in other words, to dedicated astronomy software like Celestia or Stellarium, which, among other things, have a horizon, and are as such much easier for you to to orient yourself within their frame of reference. Via Ogle Earth.