Perhaps shortly after mankind knew that the Earth rotates on its axis, other people began wondering: "What happens if the Earth just stops spinning?"
While there might be some debate as to who found out Earth's rotation first, we can all agree that started gaining momentum at least 470 years ago: when Nicolaus Copernicus published "On the Revolutions of the Heavenly Spheres" and proposed that the Earth spins on its axis. Historical records even show that Heraclides of Pontus, as far back as 350 BC, suggested the same, but was met with general disdain and unacceptance.
So what happens when our planet suddenly stops moving? We all fly.
The Earth Actually Spins Really, Really Fast
A common question that comes with the Earth suddenly stopping thought experiment is why cannot we feel that the Earth is actually spinning or rotating. The answer to this is surprisingly simple: because we are in it. The Earth, the oceans and the mountains and everything in between are all moving at about the same rate. Think of it as riding a car or an airplane: passengers feel comfortable and static as the vehicle moves, unless the vehicle changes its speed or comes to a sudden halt.
According to NASA, the Earth rotating on its own axis takes approximately 23 hours, 56 minutes, and 4.09053 seconds — this is what we call a sidereal day. Given the Earth's shape, the fastest rotation would have to be at the Equator, which moves at about 1,100 miles per hour (or 1,770 kilometers per hour). The rotational velocity, or speed of the spin, decreases to zero as we approach the poles.
Now, in a recent interview, senior geologist emeritus James Zimbelman from the Smithsonian's National Air and Space Museum, Washington, D.C. explains that should the Earth suddenly stops spinning, the angular momentum it has enacted on the rest of the planet will keep everything — from the air, water, rocks, and people presumably included — would attempt to preserve it and continue moving at the same speeds. It would pull structures apart from where they stood and would send debris into the atmosphere and outer space — sending things flying eastward, scouring landscapes all over.
Angular momentum is the rotational counterpart to linear momentum. Linear momentum is the product of mass and velocity and is generally felt when automobiles crash or suddenly grind to a halt. Angular momentum, on the other hand, is what keeps gyroscopes and tops spinning (unless an external force acts on them).
"One of the fundamentals of physics is the conservation of angular momentum," Zimbelman said in the interview. He additionally explains that once an object spins, it would take an equal amount of force applied in the opposite direction to stop it.
A Fiery, Molten End and More Craters on the Moon
Aside from all of Earth's contents sent hurling by its sudden stop, other forces at work would still act upon them and cause what might be a second wave of disasters. Gravity will still try to pull all these flying objects back to the surface of the now-stopped Earth, but with surprising repercussions. Zimbelman explains, citing Newton's classical mechanics, that objects "accumulating and moving closer together would release some of their own energy," and release of energy would cause things to heat up.
On a scale as large as planet Earth, think of it as meteorites raining all over the surface, with the energy involved most likely to melt the Earth's crust.
Similarly, Australian science communicator Dr. Karl Kruszelnicki previously explained in a 2017 ABC article that once the Earth stops, half of the planet would continuously face the Sun and the other left to the cold darkness of space.
Check out more news and information on the Earth's Rotation in Science Times.
