Our solar system is a very interesting volume of space occupied by a star orbited by 8 planets and their respective moons, a dwarf planet and an asteroid belt between Mars and Jupiter, along with two comet belts at the outer edges.
The question is, how did this system arise?
The generally accepted theory, with modifications, is that a very large cloud of mostly hydrogen and helium collected in this region of space. This cloud contained all the elements we now have plus some which we don't (Technicium and Promethium). The theory speculates that all this material was a debris field from a long since quiesent supernova explosion that occurred sometime before the solar system formed.
As this cloud of material contracted due to gravity it formed a protostar with a disk that contained all the material that is included in the planets, moons, asteroid belt and possibly the comets.
The disk material then somehow started to collect into small particles which grew larger and larger and then formed the planets and the moons asteroids etc.; even though Newtonian Physics proves this impossible due to gravitational attraction, which should have caused the more massive dense metals to end up at the center of the original gas cloud before it eventually ignighted and began fusing hydrogen into helium.
This never made sense to me. After studying physics and Newton's Laws, Kepler's laws and other things I decided it was wrong and tried to figure out how our solar system came to be.
In 1996 I developed my NOVA theory which can explain how our solar system must have formed.