Why do we have 4 ‘rock’ planets in a row then 4 ‘gas’ planets in a row?

Question

If we discount dwarf planets after the asteroid belt all planets are gas, is there a specific reason or is it just coincidence

In: 2019

Answer 1

Question seems to have been answered very well, but I wanted to add a “fun” fact. According to many theories, Jupiter is credited as Earths protector, often dominating the outer solar system with its gravity and soaking up any leftover material that might otherwise fall inward and threaten to impact Earth. We’ve even witnessed many such impacts on Jupiter.

But in the early days, it’s thought that Jupiter’s orbit would have migrated inward and may have ejected other proto-planets or even whole planets out of the solar system. But then comes the true hero, Saturn, which pulled Jupiter back out to its now stable orbit.