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What Are Earth Tides? The Moon’s Surprising Pull on the Solid Earth

Aerial photograph of the San Andreas Fault
Photo Credit
Oliverdelahaye/Shutterstock

What causes tides on Earth and more facts

Written By: Bob Berman Astronomer

Did you know the solid Earth has tides just like the ocean? These subtle shifts, called Earth tides or body tides, occur as the gravitational pull of the Moon and Sun causes the planet’s crust to rise and fall each day. While we can’t feel these movements, Earth tides play an important role in geophysics, earthquake research, and even precision scientific experiments. Understanding what Earth tides are, what causes them, and how they affect our planet offers a fascinating look at the hidden forces constantly shaping Earth.

What are Earth Tides?

Earth tides are the gentle rising and falling of the Earth’s solid crust—yes, the ground itself—caused by the gravitational pull of the Moon and the Sun. Just like ocean tides make water bulge outward, Earth tides make the land very subtly stretch, compress, and lift.

What Causes Earth Tides? 

The Role of the Moon

The Moon’s gravitational pull not only affects 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.

Read Next

The Role of the Sun

The Sun’s gravity is important, too, though lunar amplitude (Earth bulge/depression distances) is just over 2 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. At 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 3 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. 

Why Earth Tides Matter to Science

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

In some scientific experiments, Earth tides must be accounted for. For example, sensitive particle physics experiments at large particle accelerators must 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.

Earth Tides vs Ocean Tides: Key Differences

FeatureEarth TidesOcean Tides
What Moves?The Earth’s solid crustThe Earth’s oceans (water)
Primary CauseGravitational pull of the Moon and SunGravitational pull of the Moon and Sun
Typical Height Change~8 inches (20 cm)~3 feet (1 meter) on average; can exceed 30 ft in some regions
Cycle LengthAbout 12 hoursAbout 12 hours
VisibilityNot visible to the naked eyeHighly visible as water rises and falls
Where It OccursEntire solid Earth surfaceCoastal areas and bodies of water
Effects on EarthSlight crust deformation; small impacts on earthquakes & volcanoesShoreline changes, coastal ecology, navigation, erosion
Scientific ImportanceMust be corrected for in physics labs, GPS, satellites, and geophysical measurementsImportant for fishing, shipping, weather, and coastal management
Strength of Lunar vs Solar InfluenceLunar tides are just over 2× stronger than solar tidesLunar tides remain dominant but solar tides enhance or diminish them
Human PerceptionNot feltEasily noticeable

Learn more about Spring Tides and Neap Tides.

Tides
About The Author
Bob Berman

Bob Berman

Astronomer

Bob Berman is an astronomer, author, and science communicator with decades of experience making the wonders of the universe accessible and engaging. Known for his wit and insight, Bob has captivated a...
Read More from Bob Berman

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Comments

<span>Emma</span> Fri, 01/02/2026 - 06:13
So interesting! It reminded me of my grandfather knowing if you dug a hole at particular times, you would have dirt left over or not enough dirt to refill the hole. I cannot remember how he determined those times, but now I'm curious if it was related to earth tides because he was always right. The many things he said that I wish I had written down.
<span>Lina</span> Fri, 12/19/2025 - 07:38
Great article! To follow up: 1. Since they’re invisible to the naked eye, how were they found? What instruments were used? 2. Are there specific areas in our planet that are more affected by this or it’s just the entire crust at once? Thanks!
<span>Vernon Forbes</span> Sat, 08/31/2024 - 17:20
Earth tides have been implicated in earthquakes & predict how high the water is in wells. While the Missouri Dept. of Natural Resources regularly predicts river water levels for barge traffic, they didn't bother to respond to my question. The US Geological Survey told me that I had a good question but they weren't sure where I could find that kind of thing out. The Missouri Dept. of Natural Resources. So how can I find the Earth Tides for states that are not along the ocean? Vernon Forbes Columbia, MO
<span>Trisha Reilly</span> Sat, 11/16/2013 - 23:33
I am so greatful for the information you share. Absolutely everything moves with the moon. This magnificent planet is to be loved dearly each and every day. Thank you so much, Blessings, Trisha
<span>Gene2</span> Sun, 04/10/2011 - 07:35
The forces of nature are amazing in our daily lives as we take for granted life sustaining anomalies. Gravitational tugs and pulls of the celestial ballet that allow us to exist take place every moment of the day. Nature gives me another reason to enjoy the catch of the day, indelible images of my surroundings and the air that I breathe. The diversity of life ... it's like no other experience.
<span>Scaldabanco</span> Wed, 10/14/2009 - 00:06
This is amazing, I'm wondering what effect these tides have on people and animals.
<span>Brian Fritz</span> Thu, 09/17/2009 - 10:21
Fascinating!