The Man in the Moon appeared when meteoroids struck 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, Penn State astrophysicists think they know why. “I remember the first time I saw a globe of the moon as a boy, being struck by how different the farside looks,” said Jason Wright, assistant professor of astrophysics. “It was all mountains and craters. Where were the maria? It turns out it’s been a mystery since the fifties.” 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. It was called the dark side because it was unknown, not because sunlight does not reach it. Researchers immediately noticed that fewer “seas” or maria existed on this portion of the moon that always faces away from Earth.
Wright, Steinn Sigurdsson, professor of astrophysics and Arpita Roy, graduate student in astronomy and astrophysics, and lead author of the study, realized that the absence of maria, which is due to a difference in crustal thickness between the side of the moon we see and the hidden side, is a consequence of how the moon originally formed. The researchers report their results in… [Continue Reading]