If you like smartphone stargazing, the sky is now the limit. Google announced Friday that it has donated its popular Sky Map app to the open-source community, allowing fans of Android-based astronomy to "take the code and augment it as they wish."

Google Sky Map was originally created in 2009 by employees at Google's Pittsburgh office, using the 20 percent time that Google gives its engineers to "work on what they're really passionate about." The goal was reportedly to show off the sensors in Android phones, but Sky Map quickly took on a life of its own.

Photo: NASA

And now, after three years and 20 million downloads, Google loves Sky Map so much it's setting it free. It's part of a broader purge taking place at Google, where CEO Larry Page is enacting a "more wood behind fewer arrows" strategy he laid out last July. (That plan may have been inspired by late Apple co-founder Steve Jobs, who famously told Page that Google's vast portfolio of products was "turning you into Microsoft.")

While Page may not whittle Google down to just five products as Jobs suggested, he has trimmed a lot of fat since taking over the CEO job last April. Google Health, Google PowerMeter and Google Labs all shut down last year, and the company is now kicking off 2012 by closing or open-sourcing several more products, including its Picnik photo editor, Urchin analytics software and the Sky Map project.

Unlike some of its siblings, though, Sky Map seems poised to thrive in its life after Google. In addition to releasing its code, Google is working with Pittsburgh's Carnegie Mellon University "in an exciting partnership that will see further development of Sky Map as a series of student projects," according to Google's Research Blog. "Sky Map's development will now be driven by the students, with Google engineers remaining closely involved as advisors."

The Sky Map app can still be downloaded from Google, as can the newly released code.