The Speed of Earth’s Rotation Is 1,000 Miles Per Hour – Here’s Why We Don’t Feel a Thing

• The speed of Earth’s rotation is about 1,000 miles per hour relative to its axis.

• Your exact speed of rotation due to Earth’s spin depends on your latitude. The farther you are from the equator, the slower you move. And when standing at the poles, you’re essentially just rotating in place.

• Despite spinning at more than 1,000 mph, we don’t feel a thing. That’s because Earth’s rotation is remarkably smooth and consistent.

Earth’s predictable spin gives us the day and the night, governs our sense of time, and even helps stabilize our climate. But as steady as it may seem, our planet’s rotation routinely speeds up, slows down, and fluctuates in ways that scientists can, and do, measure down to a fraction of a second.

At the equator, Earth spins at a blistering speed of about 1,000 miles per hour relative to its axis. That’s roughly twice as fast as a cruising commercial aircraft. However, this breakneck pace isn’t uniform across the globe.

Your exact speed of rotation due to Earth’s spin depends on your latitude. The farther you are from the equator, the slower you move. And when standing at the poles, you’re essentially just rotating in place.

Earth’s rotation rate isn’t perfectly constant, either. In fact, the time it takes for Earth to spin once can change by milliseconds from one day to the next.

“This variation in the ‘length of day’ (LOD) is due to a complicated interplay of atmospheric changes, movement of the Earth's core, and the Moon's effect on the tide,” says Kimberly Rupley, Public Affairs Specialist at the U.S. Naval Observatory (USNO).

Read More: Earth’s Inner Core Is Slowing Down — and May Not Be Entirely Solid

At USNO, researchers track these changes with extraordinary precision. “The Rapid Service/Prediction Center of the International Earth Rotation and Reference Systems Service (IERS), located at the U.S. Naval Observatory, monitors the Earth's orientation and disseminates this information to many organizations on a continuous basis,” says Rupley.

Even though these fluctuations in the length of a day are measured in mere milliseconds, they still matter.

“At USNO,” says Rupley, “the Earth Orientation Department is responsible for determining and predicting the time-varying alignment of the Earth's terrestrial reference frame with respect to the celestial reference frame, commonly referred to as Earth Orientation Parameters (EOPs).”

These EOPs are updated daily and shared with agencies around the world, which then use them for things like precise satellite positioning and navigation on Earth’s surface.

The data used to calculate EOPs largely come from a network of radio telescopes that work together using a technique called Very Long Baseline Interferometry (VLBI).

“Through the repeated observation [same object, same time of day] of quasars and Active Galactic Nuclei [AGNs], we can measure the precise location of the object [like a quasar] on the plane of the sky and also measure the precise location of each telescope on the ground,” says Rupley.

You can blame Earth’s mildly inconsistent spin rate on our planet’s ever-shifting mass.

“Many factors like the lunar tides and our planet’s weather patterns can result in changes in the distribution of mass of the Earth, changing its shape,” says Rupley. “The rate at which the Earth rotates will then vary based on its shape, which we can then make note of through these daily measurements.”

For example, when the distribution of water on Earth shifts over time — from melting glaciers, changing sea levels, or other factors — it can slightly alter Earth’s spin, much like a figure skater who pulls in their arms to rotate faster. The same goes for interactions deep within the planet, like changes in the flow of Earth’s molten outer core.

Add to that the gravitational influence of the Moon, tectonic plate movement, changes in the jet stream, and even major earthquakes, and you can see why it’s relatively common to have millisecond-scale shifts in the length of a day.

“All the factors that contribute to the speed of the Earth’s rotation make it difficult to predict, which is why it must be observed continuously,” says Rupley. “This kind of data is vital for us in order to navigate both on Earth and in space.”

Read More: What Would Happen If the Earth Stopped Spinning?

Despite spinning at more than 1,000 mph, we don’t feel a thing. That’s because Earth’s rotation is remarkably smooth and consistent. The variations we do see are on the scale of about one millionth of one percent, says Rupley. Like passengers in a car driving at a constant speed on a straight road, if not for visual cues, you wouldn’t even know that Earth’s spinning at all.

Gravity also does a pretty great job of keeping our feet planted firmly on the ground. Although Earth’s spin does generate a small amount of outward centrifugal acceleration, the inward pull of Earth’s gravity is hundreds of times stronger. So, unless you’re stargazing or paying attention to the Sun’s position all day, you probably don’t really notice Earth’s rotation.

Nonetheless, though the ground beneath our feet feels still and unmoving, we all know it’s anything but.

Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:

• Astronomy 161: An Introduction to Solar System Astronomy. Lecture 21: The Rotation & Revolution of the Earth

• Global Geodetic Observing System. Earth Orientation Parameters

• NASA Earth Data. When a Day is Not a Day

• Cool Cosmos. Why don't we feel Earth move?

• National Radio Astronomy Observatory. Why Don’t Humans Get Thrown Off the Surface of the Earth Due to its Rotation?

Jake Parks is a freelance writer and editor who specializes in covering science news. He has previously written for Astronomy magazine, Discover Magazine, The Ohio State University, the University of Wisconsin-Madison, and more.