John Wheeler: Moon time is different than Earth time
This explanation will involve a little modern physics.
FARGO — Moon time is different from Earth time. Maxwell showed that the speed of light is the same for all points of reference. This contrasts with Newtonian physics, which shows that for objects with mass, speed is relative. A person standing by a road watches cars from both direction pass by at 60 mph. To each car, however, the other car passes by at 120 mph. However, a light ray from one star that passes by a light ray from another star appears to be going at the same speed as to an observer watching both.
Einstein rectified these two things with the concept of Space-Time from the Theory of General Relativity. One outcome is that time moves slower near more massive objects. Earth is much more massive than the moon, so time passes by slower on Earth than on the Moon by about 56 millionths of a second per 24 hours. As people colonize the Moon, a synchronized Moon time will need to be developed.