Tides

ocean · gravity · moon · cycles

The Moon pulls water. The Moon's gravity tugs on Earth's oceans, making the water bulge out toward it. This happens twice a day as Earth spins, creating high tides and low tides.

The Sun helps too. The Sun also pulls on our oceans, though it's much farther away so it pulls weaker than the Moon. When the Sun and Moon line up, their pulls combine to make super high and super low tides called spring tides.

Water rises and falls. In a single day, most ocean beaches have two high tides when water floods onto shore and two low tides when it pulls way back. This happens because Earth is always spinning under the Moon's pull.

Energy from tides. People have learned to capture the power of moving tidal water to make electricity, just like windmills catch wind power. Some countries now use tidal turbines in the ocean to generate clean energy.

Creatures follow the rhythm. Many ocean animals time their lives to the tides, moving in when water rises and hiding in pools when it drops. Crabs, snails, and fish all depend on knowing when the tide will come.