Solving the mystery of the “man in the moon”
New data obtained by NASA’s GRAIL mission reveals that the Procellarum region on the near side of the moon — a giant basin often referred to as the “man in the moon” — likely arose not from a massive asteroid strike, but from a large plume of magma deep within the moon’s interior. The Procellarum region is a roughly circular, volcanic terrain some 1,800 miles in diameter — nearly as wide as the United States. One hypothesis suggested that it was formed by a massive impact, in which case it would have been the largest impact basin on the moon. Subsequent asteroid collisions overprinted the region with smaller — although still large — basins. Now researchers from MIT, the Colorado School of Mines, and other institutions have created a high-resolution map of the Procellarum, and found that its border is not circular, but polygonal, composed of sharp angles that could not have...