Jupiter and the other gas giants eject most of these protocomets into the outskirts of the solar system (how?), forming the Oort cloud. Why are the asteroid belt and Kuiper belt still "in place"?
Minor impacts continued as the last dregs were cleared
out of the solar system. The last few major impacts may have been responsible
for things such as the tipped rotation axes of Venus and Uranus and the
formation of the Earth's Moon. The age of heavy impacts ended approximately
3.8 billion years ago (how do we know
this?) and we are left with the present day solar system (more or less...).
1. Major Prograde Satellites of Jupiter, Saturn, and UranusAs the gas giants formed, the pulled in gas and dust due to their gravitational attraction. This stuff collapsed into a disk in much the same way that the solar nebula did.2. Captured Satellites
The inner portion of these disks were warmer due to the heat of the forming planet, so we see similar gradients in composition (rock/ice mix) to those in the solar system as a whole.
Tidal forces and orbital resonances shape the orbital properties of the satellite systems.Mars's Phobos & Deimos3. Collisional origins
Many small outer moons of the gas giants
The gravitational fields and/or extended atmospheres of the early planets may have captured passing planetesimals as the solar system finished accreting.
The outer moons of Jupiter may have formed in accretion families.The Earth's moon
This scenario would explain the compositional anomolies of the moon (ie low iron content, depletion of volatiles, overabundance of refractories).