The animation below shows the gravitational action of the sun and moon on the earth's oceans, bringing this dynamic process to life. It should take from 3 to 6 minutes to download with a 28.8 modem. The world's oceans are in constant flux. Winds and currents move the surface water causing waves.
Ocean levels fluctuate daily as the sun, moon and earth interact.
As the moon travels around the earth and as they, together, travel around the sun, the combined gravitational forces cause the world's oceans to rise and fall. Imagine the earth covered completely by water. As the earth spins, this water is balanced evenly on all sides by centrifugal force. The moon has a gravitational pull on this layer of water as it orbits the earth. This pull causes the water to bulge toward the moon.