It is defined as the amount of a substance that contains as many particles as there are atoms in 12 grams of pure carbon-12. So, 1 molecule contains 6.022×10^23 elementary entities of the substance.
I'm assuming u mean "moon" and because it rotates around the rotating earth, and the side of the moon we cant see from this angle is dark, which is y we see pieces of the moon in a cycle. Its constantly turning
