The Moon Has Shrunk, and May Still Be Contracting
Newfound features hint moon has gotten smaller in recent past.
Called lobate scarps, the features are made when land on one side of a geologic fault line is thrust upward, creating a slanting wall that can be several hundred feet high and several miles long.
"If you were walking up to one of these landforms, you would see basically what looks like a stair-step in the landscape," said study co-author Thomas Watters of the Center for Earth and Planetary Studies at the National Air and Space Museum in Washington, D.C.
"It would be steep in the front on the scarp face itself and then gently sloping on the backside."
The Apollo 15, 16, and 17 missions photographed about 70 lobate scarps near the moon's equator. (Read the original