Question: How were the planets created?

Stefan Lines answered on 14 Nov 2014:

When giants clouds of dust and gas collapse to form a star, some of the material still survives. That material forms a disk around the the star. Some of the dust in the disk starts sticking together, a processes which is often helped by turbulence in the gas. When the dust sticks together, it gets bigger and bigger, until you have rocks. These rocks then grow through collisions – sometimes merging together if they hit each other slowly enough, and at the right angle. The rocks get bigger and bigger into ‘protoplanets’ and eventually planets! If these rocky, terrestrial planets get big enough then they start pulling onto them the gas from the disk too. That can turn them into gas giants like Jupiter.