Formation of moons around giant planets: the need for a more consistent scenario

Abstract:
In our Solar System, the presence of moons orbiting around planets is the rule rather than the exception. In particular, all four giant planets possess systems of regular satellites, thought to have formed in situ. This fact has long ago set the idea that the formation of moons is a natural outcome of the formation of giant planets. An important implication being that similar (and potentially habitable) worlds should be numerous in extrasolar systems.

In this context, the Galilean system, composed of four massive satellites orbiting in a compact system around Jupiter, is often regarded as an archetype. In the current paradigm, the formation of such a system is a continuous process where satellites are fed by the material accreted by their parent planet within a (largely gaseous) circum-planetary disk. 

This scenario, as formulated over a decade ago, is however hardly reconcilable with our current understanding of the formation of planets, as will be explained. A more consistent framework needs to be constructed, and some ideas towards this will be exposed.