The Spin

The Earth spins. The planets spin. The Solar System spins. Even the Sun spins. All this spinning couldn’t just be coincidence, can it? So, why does everything in the universe spin?

Let’s begin four and half billions years ago, when our Solar System began to form around clouds of helium and hydrogen. As gases of varying densities moved around space, a triggering event (maybe a supernova) caused these gases to coalesce. As the gravity of these bodies increased, they began pulling in everything around them, causing these bodies to spin. A curious phenomenon here is that, whenever this happens, the spin appears to move in the same direction: Counterclockwise.

This spin has a sort of “tossed pizza dough” effect, where you’ll find a ball in the middle and everything else around it expanding outward in a disc shape. This is a common shape found throughout the universe and is attributed to the laws of physics.

Eventually, all these elements collide and form larger and larger bodies that become planets, moons, etc., all the while maintaining the angular momentum as inertia keeps the spin going. This is what causes the spin, and it's the reason why everything appears to follow the same kind of spin. It is slowing down, yes, but at a slower rate than humans can consciously detect.

For people who prefer more visual explanations, this video from DNews explains what causes everything in the universe to follow the unending circular paths that they travel.

Notable Exceptions

Of course, not everything spins the same way. There is a notable exception in our own solar system: Venus. The planet seems to be spinning clockwise, and astronomers aren’t quite sure why. Two possibilities arise: One is that the planet somehow flipped upside down, or that the planet gradually stopped spinning counterclockwise, paused and started spinning clockwise.

Another exception to the Solar System’s counterclockwise club is Uranus, which may have once been knocked onto its side and now spins differently than the other planets in the solar system.

Regardless of whether it spins clockwise or counterclockwise, everything in the universe moves and spins: From small asteroids to entire galaxies. Gravity, momentum, inertia ensure that bodies big and small act upon each other, causing everything to move and spin.

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