A Nice Story (Gomes, Levison, Mordibelli, & Tsiganis)
- The 4 giant planets formed within 15AU or 20AU of the Sun.
- They were probably in mean motion resonances with one another.
- 2J:3S - 2S:3U - 2U:3N or
2J:3S - 2S:3U - 3U:4N
- Stops planets from falling into the Sun (Crida & Morbidelli)
- Beyond them was a ~35 Earth-mass disk that extended to ~30AU.
- The 4 giant planets slowly spread due to leakage from this disk.
- Jupiter and Saturn crossed a mean motion resonance at 700Myr
- The 1:2, 3:5, and even 11:8 can do it.
- Uranus and Neptune went unstable and scattered into the disk.
- Uranus and Neptune evolve onto current orbits due to interactions with the disk.
And everyone lived happy ever after.
