Question: if your smart why does the planets orbit the sun?

Michael Cook answered on 26 Jun 2012:

I think the main reason is that the Sun is much, much larger than any of the planets. That means it has a stronger gravitational pull. Everything in the universe has a gravitational pull – the desk in front of you, the computer, even you! But things that are quite light (like the desk, the computer, and you) have very weak gravitational pulls.

Huge things, like the Earth, can pull in tinier things for this reason (that’s why you stick to the floor instead of floating off into space – Earth is pulling you in with gravity, right?). Similarly, the Sun can pull the Earth towards it because it too is much much larger.

In order for something to orbit something else, it has to move in two directions at once, sort of – it needs to move slightly away from the thing it’s orbiting, and at the same time it has to have a force pulling it towards the thing it’s orbiting. This second force is the reason why the Sun couldn’t orbit the Earth – the Earth isn’t strong enough to pull it in.

I hope that wasn’t too garbled an answer! There’s a diagram I found to help here (it shows the moon orbiting earth): . The two arrows are the two forces I mentioned.