55-year-old dark side of the Moon mystery solved
From Penn State -- The Man in the Moon appeared when meteoroids struck the Earth-facing side of the moon creating large flat seas of basalt that we see as dark areas called maria. But no "face" exists on farside of the moon and now, astrophysicists think they know why. This mystery is called the Lunar Farside Highlands Problem and dates back to 1959, when the Soviet spacecraft Luna 3 transmitted the first images of the "dark" side of the moon back to Earth.
Read the full article at Penn State News (link is external).
Image: Composite image of the lunar farside taken by the Lunar Reconnaissance Orbiter in June 2009. Note the absence of dark areas.