Is there a reason why we have four “rock” planets lined up followed by four “gas” planets in a row, or is it merely coincidence?

Question

Is there a reason why we have four “rock” planets lined up followed by four “gas” planets in a row, or is it merely coincidence?

In: Planetary Science

Answer 1

The reason is Saturn. Following a model for solar systems that is most likely a Jupiter sized gas gain forms and gets closer to the start and clear all orbits. The current hypothesis is the because a second gas gain formed – Saturn, it pulled on Jupiter in the other direction and there was a chance for orbits for rocky objects to exist. So the question moves to – why was there a second gas giant right after the first one. Probably chance.