The Moon is shrinking! Well, a little: new results from the Lunar Reconnaissance Orbiter indicate that over recent geological time, the Moon has shrunk by approximately 100 meters in diameter! Here's the evidence, or at least one piece of it:
[Click to unshrinkenate.] That image shows the Gregory scarp, a cliff across the surface of the Moon. Scarps like these have been known for centuries -- I've observed many myself using a backyard telescope -- but it was always thought they were big and restricted to just some areas on the Moon. LRO, though has found many smaller scarps, and also importantly that these scarps are distributed globally, all across the surface of our nearest neighbor in space. What does this have to do with shrinkage?
This diagram shows how scarps are formed: thrust faults. If the Moon shrinks, even a little, the surface shrinks too, and gets compressed. This ...
