Earth's gravity is making patterns in the thousands of small cliffs that wrinkle the shrinking surface of the moon, according to a new in Geology. Scientists determined the moon was shrinking—its surface has moved about 300 feet closer to its core over 4 billion years—back in 2010 based on approximately 84 small cliffs, called lobate scarps, discovered on its surface, the Washington Post reports. The scarps, which are less than 6.2 miles long and 300 feet high, are formed when the moon's cooling interior causes the moon to contract and its crust to buckle, explains a NASA post at Science Daily. But if that's all that was happening, the appearance of the scarps should be random.
"This is not what we found," says Thomas Watters of the National Air and Space Museum in Washington. "There is a pattern in the orientations of the thousands of faults and it suggests something else is influencing their formation, something that's also acting on a global scale—massaging and realigning them." In the five years since 2010, NASA's Lunar Reconnaissance Orbiter has discovered more than 3,000 more lunar cliffs, and an analysis of them confirms scientists' suspicions that Earth's gravitational tidal forces are affecting them, says NASA. All the more reason to check out next week's combo of a supermoon and lunar eclipse, and Discovery has the details on that. (Humans may finally land a probe on the dark side of the moon.)