Differences between the Moon’s near and far sides linked to colossal ancient impact

The face that the Moon shows to Earth looks far different from the one it hides on its far side. The nearside is dominated by the lunar mare—the vast, dark-colored remnants of ancient lava flows. The crater-pocked far side, on the other hand, is virtually devoid of large-scale mare features. Why the two sides are so different is one of the Moon’s most enduring mysteries.