In another model Jupiters help Earths to take shape. The leftovers from the first giant gas planets to form from the disk of gas and dust provide raw material for smaller, rockier planets to form by Accretion. Gravel and rocks clump together to form hundreds of planetary embryos about the size of Earth’s moon.

Jupiter’s gravitational pull causes these planetary embryos, which would otherwise remain in their individual courses, to collide and, smashing into each other, they grow to form a handful of Earth and Mars-size planets.

This third model acknowledges the formation of the gas giants first, then rock planets later, as opposed to all the components of the system forming simultaneously - so the sequence is different. But it still builds on the understanding that they all form by Accretion, and generally fixed in their orbits.