It’s a big day for astronomy buffs. Google has announced an enhancement to its popular interactive mapping software, Google Earth, that incorporates more than one million photos from the Hubble Space Telescope, the Palomar Observatory, and the Sloan Digital Sky Survey. The feature, called Sky, stitches together the pictures to reveal stars, galaxies, and planets.

The project grew from a handful of Google engineers’ basic interest in astronomy and in sharing that information with the public. At this point, the company has no plans to make money from Sky.

One of the most exciting aspects of this announcement is that, as with Google Earth, anyone can make mashups with Sky, overlaying extra information to enhance its value. Already, constellation outlines have been added, as well as guides to backyard stargazing and an animation of lunar positions. Researchers are developing mashups of cosmic explosions as well. As more mashups are added, it’ll be fascinating to watch and see how amateurs and professionals make the sky a more interactive place.

Screen shots from Sky: