what makes the earth spin and keep spinning?


what makes the earth spin and keep spinning?

In: 28


When the Solar System formed, it formed from an incomprehensibly large cloud of gas called a *stellar nursery.* As it collapsed under gravity, pockets of higher density formed by chance, and started gathering more and more gas towards them; these pockets would go on to become the planets.

As these pockets continued to collapse, *conservation of angular momentum* (if you’ve ever watched an ice skater start spinning faster when they tuck their bodies in, think of that but `l a r g e`) made the pockets start to spin faster.

The Earth’s spin is an artifact of the spin it had when it was created, and it keeps spinning because there’s no friction in space to slow it down.

(Technically, the pull of the Moon’s gravity *is* having an effect, but it’s teeny-tiny: 400 million years ago, Earth took 22 hours to rotate instead of 24.)


When planets are coalescing not all debris falls straight smack bang into the centre of mass some will hit off centre and like kicking a football (the proper round ones) if you kick it off centre you introduce a spin.

The hundreds of billions of impacts to a forming planet will give it a spin and without anything to stop it it will continue to spin.

This is why Earth’s days are slowly getting longer because the tides cause drag slowing the earth’s rotation.

When the solar system was being formed watch was hit by the moon which was much larger back then, about 1/3 of earth came from the moon. It knocked into earth and made it spin leaving a bunch of itself behind in earths orbit.