Love makes the world go around?

Our Solar System was formed approximately 4.55 billion years ago within a cloud of hydrogen. Then, possibly, a massive shock wave from a nearby supernova gave it a sudden kick, which forced a region of the cold gas to fall inward through its mutual gravity. As it collapsed, the cloud began to spin in a counter-clockwise direction. This was caused by what is known as the conservation of angular momentum.

Imagine all the individual atoms in a cloud of hydrogen. Each particle has its own momentum as it drifts through the void. As these atoms attach to each other, they need to average out their momentum. It is possible to average out to a perfect zero, though it is highly unlikely.

To make the concept of the conservation of angular momentum a little easier to understand, one only needs to look at a figure skater.

When a figure skater wants to spin faster, he or she pulls in his or her arms. In much the same way, the collapsing Solar System, with its averaged out particle momentum, began to spin much faster.

This is the conservation of angular momentum at work.

As the Solar System spun more rapidly, it flattened out into a disk with a bulge in the middle.

We see this same structure throughout the Universe: the shape of galaxies, around rapidly spinning black holes, and we even see it in pizza restaurants.

The Sun formed from the bulge at the centre of this disk, and the planets formed further out. They inherited their rotation from the overall movement of the Solar System itself. Over the course of a few hundred million years, all of the material in the Solar System gathered together into planets, asteroids, moons and comets.

Then the powerful radiation and solar winds from the young Sun cleared out everything that was left over.

Without any unbalanced forces acting on them, the inertia of the Sun and the planets have kept them spinning for billions of years. And they’ll continue to do so until they collide with some object, billions or even trillions of years in the future. So this proves to all you Valentines out there, that love does in fact not make the world go round.

Still, have a happy Valentine’s day out there and stay safe all you lovers.