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Cosmic Happy Face Stamped into Mercury Crater (Photo)

The central peaks of this complex crater on Mercury formed in such a way that it resembles a smiling face. This image was taken by NASA's Messenger spacecraft.

NASA spacecraft maps planet Mercury

The closest planet to the sun hasn't received as much scientific attention as some of its more flashy solar system neighbors, such as Mars, but NASA's Messenger spacecraft is helping to close the gap. The probe has been in orbit around Mercury since March 2011, and its team announced Feb. 28 that the spacecraft had finished mapping the planet's surface.