Today, Google released a Sky mode in Google Earth, which allows navigation of the celestial orb similar to the navigation of the Earth that Earth mode gives. This is likely related to the deal that Google signed with NASA last year. I downloaded the newest version of Google Earth (4.2) to give it a try.
To switch between Earth mode and Sky mode, you can click on the circular space icon on the right side of the toolbar or use the View menu and select “Switch to Earth” or “Switch to Sky”, depending upon what mode you are in at the time. The program always loads in Earth mode.
The tool bar in Google Earth 4.2
The first thing I noticed about it was that it was completely separate from the Earth imagery. When I clicked on the Sky/Earth toggle button, it the server login window that comes up when Google Earth first opens came up and it did again when going back to the Earth. For those unacquainted with Google Earth, this is not a personal login, but rather the program itself connecting to the Google server that hosts the information needed. This takes a little time, so it’s not a quick switch between Earth and Sky mode.
Like Google Earth, the imagery is a patchwork of different images from different sources, so the coloration differs in very geometric ways. For instance, this is the view seen when first switching to Sky mode from my hometown of Neenah, WI if all layers are turned off:
The patching together of images is especially obvious when looking at features in the sky that have Hubble imagery. For instance, take the Orion Nebula:
My overall impression of Sky mode was that it wasn’t very polished While moving over the sky by clicking and dragging is rather smooth, movement during the equivalent of the “fly to” feature on Earth mode is is sometimes jagged, especially over longer distances. I suspect this may have to do with trying to navigate on the inside of a sphere rather than the outside, which is what is done in Earth mode.
When you first access the sky portion, it moves to the portion of the sky that would be visible from the location you were looking at in the Earth section, but doesn’t have an option to move back to that area without switching and forth from Sky to Earth, which is rather annoying since this takes quite a bit longer than simply moving back to the view at the beginning would staying within sky mode.
Another problem is that the planets and moon features were pretty basic. You can only track their movement over a limited timeframe (about two months centered around the current day). Furthermore, they do not appear according to their normal size or brightness in the sky but rather as images moving over the background with the moon changing phases as time passes. This means that not only do they not look as they would to a stargazer but also reach a point where they do not zoom as the rest of the stars do, making for a strange effect.
And on that track, there doesn’t seem to be a way to add the horizon to sky mode, so it isn’t very useful as a stargazing application, but that doesn’t seem to be what it’s meant to do. It seems to be a way to find sky imagery by its location in the sky more than anything. Here are the layers available in Sky mode (collapsed):
“Constellations” contains “Constellation Lines” and “Constellation Names” layers. “Backyard Astronomy” contains layers for the Messier Catalogue, the New General Catalogue, and the Yale Bright Star Catalogue. “Hubble Showcase” contains a variety of Hubble images (such as the one of the Orion Nebula above) that are categorized by type of object. The moon and planets layers are discussed above and the last two layer groups are meant to be educational.
Personally, this isn’t as fun as the Earth mode is and though it was nice to be able to see how the images fit together and to zoom in on them, one can look at them just as easily access them at the Hubblesite gallery.
As for a good application for stargazers, try Stellarium. If you like the idea of flying around the solar system and stars and looking at 3-D representations of the planets, try Celestia. Both of these are open-source programs that work on Windows, Mac OS X, and Linux.