Earth Tides | The Old Farmer's Almanac

Earth Tides: Yes, the Land Has Its Own Tides, Too!

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What causes tides on Earth and more facts

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Have you ever heard of an Earth tide? Yes, like the oceans, the Earth has tides, too! Learn about what causes Earth tides and more interesting facts.

What Causes Earth Tides? 

The Moon’s gravitational pull does not only affect our bodies of water. The solid crust of Earth also moves to a lunar rhythm. The Moon’s gravity causes our oceans to bulge out on the side closest to the moon and the side farthest from the moon. These bulges of water are high tides. The low points are where low tides occur. Learn more about how the Moon affects tides.

The Sun’s gravity is important, too, though lunar amplitude (Earth bulge/depression distances) are just over two times the height of solar amplitudes. In fact, when the Moon and Sun are aligned (at the new Moon and the full Moon, we see the greatest tidal range. The quarter Moons, the tidal range is at a minimum. 

How Tall Are Earth Tides?

While the seas rise and fall by a worldwide average of three feet daily, the ground oscillates by about 8 inches (scientists measure this with satellites). 

This mutation is not merely a surface phenomenon; the entire planet undergoes constant and complex rhythmic deformations. The tides go through a single cycle (high and low tide) every 12 hours. 

What’s the Effect of Earth Tides?

Some scientists say that Earth tides are important, though not as important, as ocean tides. Earth tides are correlated to earthquakes as well as volcanic events. 

Sometimes, with scientific experiments, Earth tides needs to be taken into account. For example, sensitive particle physics experiments using those huge particle accelerators have to compensate for tidal variations.

However, overall, there isn’t much effect. Indeed, what’s remarkable is that they’re so small. It’s evidence that our planet is incredibly well–built. To have a body as massive and as near as the Moon, and to have our planet changed so little by its presence, means that Earth is one of the solar system’s construction success stories.

Learn more about Spring Tides and Neap Tides.

About The Author

Bob Berman

Bob Berman, astronomer editor for The Old Farmer’s Almanac, covers everything under the Sun (and Moon)! Bob is the world’s most widely read astronomer and has written ten popular books. Read More from Bob Berman

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