Question: why are their planets????

Michael Cook answered on 27 Jun 2012:

Interesting one! I had to look up this one to be sure, and it turns out that astrophysicists haven’t actually decided for sure how this happens. Here’s a good theory though (I like it, anyway):

When stars like our sun form, they are normally quite large and have huge gravitational pulls! You might know that the bigger something is, the bigger its gravitational pull, right? Well, a lot of space consists of tiny bits of dust and gas floating around and doing nothing. But when it comes into a gravitational field, it starts to be pulled around. There’s a question about things orbiting the sun here: /niobiumj12-zone/2012/06/26/if-your-smart-why-does-the-planets-orbit-the-sun/.

Now, on their own these tiny bits of dust don’t do much. But if they start bumping into other bits of matter, they start to collect and stick together. And these little chunks get bigger and bigger until they start having enough gravity to pull in dust themselves. Eventually, over a long period of time, planets like Earth are formed from these chunks slowly adding on top of each other.

I don’t think we know for certain if the above is true yet. But it sounds like fun to me! This whole planet was once a bunch of dust floating around the sun. Pretty cool, eh?