How does the Moon affect the ocean tides?
Without the Moon, Earth would have no ocean tides, or periodic rises and falls in the level of the sea. Tides occur because the Moon exerts pull (or gravity) on the ocean water, causing it to rise and fall on a regular schedule. The gravitational pull of the Moon tugs on the surface of the ocean until its surface mounds up and outward in the direction of the Moon. When the mound of water has reached its highest point it is called high tide. On the side of the Earth opposite the Moon, the centrifugal force caused by Earth’s rotation produces another mound of water and high tide on the opposite side of the globe. Somewhere in between these two high tides are two flat areas on the surface of the ocean, which are low tides.