Why do planets orbit the sun counterclockwise and not clockwise?

508 views

This is the same for satellites and solar systems. Why do they just orbit in one direction. Also, why do they rotate on their axes in a certain direction?

In: Physics

Take a clear clock and look at it from the ‘front’ and its rotating clockwise and from the ‘back’ its counter clockwise. The planets are rotating clockwise and counterclockwise depending on how you view them

Because the aggregation disk the planets formed from happened to spin in that direction by random chance.

But it’s only counterclockwise when you declare north to be “Up” wich is arbitrary.

The solar system condensed from a swirling cloud of gas and dust, so the planets orbit in the direction the cloud was swirling. Same with the formation of planets and moons — as gravity pulls in material, the material starts swirling and a spinning planet or moon is formed.

That was the way the disk they formed from was spinning, and conservation of angular momentum means that everything will keep going in that direction unless something makes it go in another direction.

> This is the same for satellites and solar systems.

For artificial satellites, it’s because launching in the direction of rotation is easier and cheaper, because you’re adding the rotational velocity to your craft’s velocity rather than working against it.

For natural satellites it’s conservation of angular momentum again.

If you look at them from the south, they spin clockwise. So your question is basically asking why astronomy advanced the most in the northern hemisphere.

Since the sun and all the planets formed from a cloud of gas and dust, they mostly have the same spin as that cloud did originally. The axis of the spin points to a random direction in the sky. By convention we record the direction of the north pole axis and say that objects rotate anticlockwise. We could just as easily choose the direction of the south pole and say that objects rotate clockwise.

Another answer is that our definition of clockwise comes from (northern hemisphere) sundials. In other words the sun is defined to appear to move clockwise across the sky. For the sun to appear to move clockwise, we must be watching it from something that is rotating anticlockwise.

I think people might be missing the point of your question. I am assuming you are curious why they are all going in the same direction rather than caring if it is clockwise or counterclockwise. This is because there would have been stuff going all different directions early on but slow things crash into each other and are destroyed/broken up or pushed in a new direction until eventually you are left with only the items going in the dominant direction (and which way the dominant direction was, was just chance).