Boulders keep losing their footing on slopes on the moon: they roll, jump or slide into the valley. What is the trigger: moonquakes or meteorite impacts?
Since the lunar satellite Lunar Reconnaissance Orbiter meticulously photographed the lunar surface, images of boulders that have broken loose from crater walls or mountain flanks and rolled down valleys have appeared again and again. They have left extensive tracks in the terrain that have survived for a very long time, undisturbed by atmospheric erosion.
However, the mobile chunks are not completely new to the scientists: the American probe Lunar Orbiter 5 had them in for the first time
