Lunar gravity is about 1/6th of Earth gravity. Clocks slow down due to gravity (Einstein's relativity). Thus, clocks tick faster if there's less gravity. Aside

Lunar gravity is about 1/6th of Earth gravity. Clocks slow down due to gravity (Einstein's relativity). Thus, clocks tick faster if there's less gravity. Aside: we can measure this effect on Earth, between the foot and top of a mountain. Tom Scott has a video about exactly that.