Main Reason Why Massive Planets Orbit Close to Stars
https://www. youtube. com/watch?v=VCP9z5AW08Q
It seems that our solar system, with small rocky planets close to the star and gas giants far away from the star, is rather unusual. It is much more common that the biggest planets orbit close to the star.
Planet formation simulations suggest that this depends on the amount of mass around a star in the beginning.
If the initial amount of mass is high, there are more collisions, and as a result, more momentum is lost and most of the mass ends up closer to the star.
But if the initial mass is low, there will be less collisions, and the bigger planets stay in a more distant orbit.
This suggests that earth-like planets (rocky planets in the Goldy Locks zone) may be much rarer than originally thought.