What Would Happen if the Earth Stopped Rotating?

You have to admit, it doesn't feel like you're spinning around the center of the Earth at hundreds of miles an hour, so it's not hard to cut our scientific forebears some slack for assuming the planet was stationary and that the sun rotated around it.

Thankfully, Copernicus set the record straight with his heliocentric model, and we now know that the Earth spins on its axis as it revolves around the sun. But why does our planet spin in the first place?

Remember Newton's first law of motion? It states that an object remains in whatever state of motion it's in — unless another force acts upon it. Basically, the Earth is rotating because it's been doing that as long as it has existed.

Before there were planets in our solar system, there was a spinning, nebulous cloud of dust with our sun at the center. Over time, these dust particles collided into one another and began to stick, forming larger and larger rocks and, ultimately, planets through a process known as accretion.

But remember, the cloud of dust — or accretion disc — was rotating from the start.

As the particles that formed the Earth began to stick together, that momentum was conserved, causing the growing planet to spin faster and faster, much the way a figure skater does when they pull their arms in toward their body.

By the time the Earth had formed, it had all of the angular momentum it would need to keep spinning to this very day. Just how fast is that, anyway?

As any police officer can tell you, measuring the straight-line speed of a car — or most any object — is a fairly simple and reliable process. However, measuring the speed of a rotating object like the Earth is slightly more complicated. After all, if you stand at one of the poles, you'll spin right along with the rest of the Earth, but you'll be stationary with respect to its center.

Stand on the equator, though, and you'll have a linear speed of 1,036 miles per hour (1,667 kilometers per hour) [source: Esri]. That's faster than the speed of sound, and one of the reasons we tend to launch rockets toward the east [source: NASA].

The difference between linear speed at the poles and the equator produces an interesting phenomenon called the Coriolis effect. The effect is easiest to visualize if you think about someone setting out in a plane straight for the North Pole from the equator. Since the plane retains the lateral speed of the equator, it appears to curve with respect to the Earth as it approaches the slower moving poles.

Let's get our admittedly far-fetched assumptions on the table:

For starters, Earth would now take a whole year to do what it pulls off in a day: cycle from night to day and back. Cities would spend half the year with nothing but night sky and half the year in full sunlight, just like the North and South Poles do today.

And, like the poles, every region would still experience different seasons, but the temperature swings from season to season would be much greater for areas along the equator.

An equatorial region would spend infernally hot months very close to the sun, while that area's global counterpart would spend dark, frigid months very far away from it. That's trouble for the plants and animals that have adapted to the climate of a region and, consequently, for the people living there as well.

Is Relocation Possible?

What's that? You're relocating to the relatively stable (but still awfully cold) polar regions? Bad move. They're deep underwater. In fact, the boundaries between ocean and land on a spin-free Earth would look nothing like they do today.

Because the Earth rotates, centrifugal force causes the planet to bulge along the equator. No rotation, no bulge. Without that bulge, all of the extra water held in place along the equator would go rushing back toward the poles.

Esri, a company that develops geography-focused technology, modeled the world's land and oceans after its equatorial bulge subsided. They found that the Earth would have a band of land — one giant supercontinent — that circles the equator and separates two massive oceans to the north and the south.

Bye, Bye Magnetic Field

As if that weren't enough, Earth's magnetic field might go away, too. This field acts as a protective shield by deflecting charged particles from the sun and redirecting cosmic rays, preventing them from directly hitting the Earth's surface and harming our planet and its atmosphere.

According to the geodynamo theory, Earth's magnetic field is generated by the movement of molten iron and nickel in the planet's outer core. Heat from radioactive decay and residual heat from Earth's formation create temperature differences in the outer core, leading to convection currents.

These currents, combined with Earth's rotation, create electric currents, which, in turn, generate the magnetic field through a process known as the geodynamo effect.

Earth's rotation plays a crucial role in the generation of its magnetic field through the geodynamo effect. Without rotation, the convection currents in the liquid outer core that drive the geodynamo would diminish, leading to a gradual weakening of the magnetic field. But don't worry, this process would take thousands to millions of years.

How Will Humans Fare?

Where does that leave us? Humans are an adaptable species with powerful technology at their disposal, but survival in this new environment would be a challenge.

Sure, we could try to light our homes in the darkness and heat and cool them (at great cost) during wild temperature swings, but not everything would be under our control.

Could crops survive the extremes of this new world? Could any plants? If not, the entire food chain would be in danger. Perhaps we could find new crops or modify existing ones to tolerate this new environment. Or maybe we would become dependent on perennials that return with warm weather.

It's actually a little comforting to think that, while the world will probably become a hellish place to live, at least our decorative hosta beds might be OK.

Is there anything slowing the Earth's rotation down? Sure, but don't adjust your watches just yet. The forces changing the speed of the Earth's rotation make an extremely small impact.

Earth's rotation is gradually slowing down, primarily due to the gravitational pull between Earth and the moon. This gravitational interaction gives rise to a phenomenon known as tidal friction.

As the moon orbits Earth, its gravity creates tidal bulges in our oceans, which cause a continual dragging effect between these bulges and the solid seabed. This friction acts as a braking mechanism, transferring some of Earth's rotational energy to the moon's orbital energy, effectively slowing down the rotation.

While the rate of deceleration is minuscule and imperceptible in our daily lives, it accumulates over geological time scales.

Other factors, including the redistribution of Earth's mass due to processes like glacial rebound and atmospheric drag, also contribute to the gradual slowing of Earth's rotation, leading to a lengthening of our day by approximately 1.7 milliseconds per century [sources: Space.com].

Weather systems can also change the planet's rotation, with winds applying a braking force to the planet's surface. As we all know, the Earth is getting hotter, so some may wonder if climate change plays a role in this slowdown. Surprisingly, it does not. But earthquakes do.

In fact, the intense shaking of Earth's surface can mess with the length of the day by actually redistributing the Earth's mass. The 2011 earthquake that struck Japan actually accelerated the Earth's spin (because it shifted the mass toward the equator) and shortened the day by 1.8 microseconds [source: NASA].

So, the next time you complain about the day being too long or too short, don't despair: It's changing all the time.

This article was updated in conjunction with AI technology, then fact-checked and edited by a HowStuffWorks editor.