What If The Earth Stopped Spinning?

The Earth is spinning, and we are spinning with it. But what if it suddenly stopped? First off, you’d gain weight—but that would be the least of your worries. The spin of our planet is crucial, impacting everything from gravity to time itself.

At the equator, the Earth spins at about 465 meters per second. Closer to the poles, that speed decreases; here in San Francisco, it’s around 368 meters per second. If you could float above the Earth, you’d see it spinning beneath you at that speed. But when you jump, you don’t feel the Earth moving because you’re already in motion with it.

Now, if Earth were to come to an abrupt stop, everything not firmly anchored would be flung eastward at over a thousand miles per hour. While you wouldn't be hurled into space—since escape velocity is 24,800 mph—you’d effectively become a human projectile. The atmosphere would gradually slow down, so people in airplanes might have a better chance of survival, while astronauts on the ISS would be safe for a while. However, those on the ground would face disaster, as runways would turn into treacherous landscapes.

Initially, those near the poles might escape the worst of it, but soon, violent winds akin to those near an atomic bomb explosion would create unprecedented storms. The friction from the stopped Earth colliding with these winds would cause massive fires and erosion. The day length would change drastically; without rotation, we’d experience 365-day-long days, with the Sun appearing to freeze in the sky.

Moreover, without the Earth’s spin, our magnetic field would collapse, exposing us to harmful ionizing radiation from the Sun. Oceans would surge onto land in colossal tsunamis, reshaping our planet as gravity would pull water toward the poles. The Earth, no longer bulging at the equator, would gradually compress into a more spherical shape. While this scenario is unlikely, the Earth’s rotation is indeed slowing down—more on that shortly.

So why can’t we feel the Earth spinning? The answer lies in inertia. The Earth is enormous, and the gradual change in velocity is too subtle for us to register, much like a car making a long turn over hours. As we move, the centripetal force keeps us grounded, counteracting our natural tendency to float away. If the Earth stopped spinning, you would weigh about 0.3% more at the equator. If it spun 17 times faster, you’d feel weightless.

Now, let’s talk about time. A second is defined by the oscillations of a cesium-133 atom. After 9,192,631,770 oscillations, one second has passed. This precise measurement is crucial because Earth’s rotation is irregular. Changes in mass distribution—like earthquakes or melting ice—affect the rotational speed. Tides caused by the Moon also drag against Earth’s spin, causing a gradual slowdown.

These changes are slight but accumulate over millions of years. In about 140 million years, a day on Earth could stretch to 25 hours. To keep our timekeeping accurate, scientists rely on atomic clocks and observe distant stars to measure Earth’s rotational speed. When discrepancies arise, they adjust our clocks by adding or subtracting leap seconds.

Since 1972, 25 leap seconds have been added to our timekeeping. This means that our understanding of time is somewhat manufactured, with periodic updates to ensure accuracy. As Demetrios Matsakis, Chief Scientist of Time Services for the US Naval Observatory, puts it, “we save lives and we end lives… without completely understanding exactly what life is, or what time is.”

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