What Are Tides?

Tides are caused by the gravitational attraction of the moon as it orbits the Earth, and to a lesser extent, to the Earth as it orbits the Sun.

The moon pulls most on the water nearest to it, creating a high tide bulge of water. On the opposite side of the planet, about 7,926 miles (12,760 km) away, the moon's pull is much weaker and the water is left to form another high tide bulge.

The Earth's tidal bulges follow the position of the moon, and to a lesser extent, the sun. As the angles of these two bodies in relation to the Earth increase and decrease, so do the tidal bulges.

The moon's gravity tugs at the earth, causing ocean water to slosh back and forth in predictable waves called tides. That constant pull adds energy to the ocean.

Tidal bulges move around the Earth every day. However, the Earth has continents that disrupt the even flow of water, so a complex pattern emerges with places where the water stretches out more toward the moon, and places where it doesn't really deform at all.