Tides: How the Moon Pulls on the Ocean

0:00Why does the sea rise up the beach and then fall back again?

0:06This rising and falling of the sea is called the tide.

0:11The highest water is high tide, and the lowest is low tide.

0:16Here is Earth and its ocean, seen from far out in space.

0:21The moon is the main cause of the tides.

0:25The moon's gravity pulls on Earth and its ocean.

0:29The pull makes the ocean bulge out toward the moon.

0:33The ocean also bulges on the far side of Earth.

0:37Earth spins around once each day.

0:42When our beach turns into a bulge, the water rises to high tide.

0:47Between the bulges, the water falls to low tide.

0:52So most beaches get two high tides and two low tides each day.

1:00At low tide, sea water stays behind in tide pools on the rocky shore.

1:06Tide pool animals like sea stars and crabs live with the rising and falling tides.

1:13The moon's pull and Earth's spin make the tides rise and fall.