I understand how conservation of momentum leads to planet formation and planet rotation. However, after studying this model, I have ran into a point of confusion that I cannot find the answer to: Why dont the planets collapse into the sun just as dust particles collapsed inward via conservation of angular momentum to form the planets in the first place? What distinguishes the two situations? My two potential theories (pardon any silly answers, I am an amateur): * The velocity, size, distance, etc of the planets are just right that they stay in that equilibrium. * The accretion process stopped after the sun reached some set stage. Perhaps study the stages of the sun? Thanks in advance!!