The 4 giant planets formed within ~18AU of the Sun.
Beyond them was a massive disk that extended to ~30AU.
The 4 giant planets slowly spread due to leakage from this disk.
Jupiter and Saturn crossed the 1:2 mean motion resonance at 700Myr.
Uranus and Neptune went unstable and scattered into the disk.
Produced the lunar Late Heavy Bombardment, Trojan asteroids, and the Kuiper belt.
Uranus and Neptune evolve onto current orbits due to interactions with the disk.
With very few free parameters it:
Produces the correct giant planet orbits.
Produces the correct Trojans (both for Jupiter and Neptune).
Produces the correct orbits for the Kuiper belt.
Produces the LHB.
This talk can be found at
We are grateful to NASA's Origins and PG&G programs for support.