The so-called “Nice model” describes dynamical evolution of the outer Solar System since the time when the gas was removed from the protoplanetary disk. In this model, the giant planets underwent a dynamical instability which played a major role in shaping the present-day Solar System. This instability could have happened several 100 million years after the planets formed. The Nice model can explain several observations in the Solar System, including the orbits of the giant planets, the existence and the orbital structure of several small body populations (e.g., Jupiter’s Trojans), and the late heavy bombardment.
There are two versions of the Nice model.
The first one (Nice I) was presented in 2005 in a trilogy of papers published on the Journal Nature. In that version of the model, the assumption was made that the giant planets formed in a more compact configuration than their current one, with a ratio between the orbital periods of Saturn and Jupiter smaller than...