The contractions of the moon cause moon tremors: the moon shrinks and can, as a result, generate "moon tremors"

The interior of the moon it's cooled down and, as a result, has gained about 150 feet over the last hundred million millions of years, leading to a phenomenon known as "moon tremors", according to data from the NASA.

Similar to the skin of a grape when it is reduced to raisin, the moon wrinkles as he gets smaller. And as it becomes "skinner", the moon is actively generating moonshells along the faults. When the fragile crust of the moon breaks, it creates visible cliffs resembling steps when parts of the crust are pushed onto each other. These faults, "high and extending over a few kilometers" at the surface, remain active and move in response to the gradual reduction in the size of the moon.

"Some of these earthquakes can be quite strong, around five on the Richter scale," said Thomas Watters, senior scientist at the Smithsonian National Air and Space Museum in Washington. The reported data was recorded using the seismometer placed on the moon during five Apollo missions, and NASA's Lunar Reconnaissance Orbiter captured 3,500 images.