Each day the tides at any given place on Earth occur about an hour later then on the previous day. Since the Moon passes overhead about an hour later each day, it was long ago thought that the Moon had an effect on the tides.
Differential Forces
One should consider a simple water molecule in the ocean. It is attracted gravitationally by the Earth, but it also "feels" an attraction from the Moon (the attraction to the moon is much smaller though because the Moon is much further away and much less massive than the Earth). …
