Material captured by the giant planets during Phases 1 and 2 would have been captured predominantly in the equatorial plane and, prior to accretion, would have formed a circumplanetary disk in exactly the same way as a circumstellar disk of material formed about the Sun. These disks would also have had significant variation of temperature with distance, both due to heating from the central hot planets (generated by the release of gravitational energy by accretions), and by turbulent mixing. Planetesimals captured early in these disks would probably have been disrupted by turbulence and collisions with other planetesimals, and hence the current satellites probably reformed from material that had been disrupted by accretion into the circumplanetary disk and had been thermally reprocessed by the radial temperature gradient. Such a model explains why most of the satellites about the giant planets are in the equatorial plane of the planet. It also explains why the compositions of Jupiter's Galilean satellites (Io, Europa, Ganymede, and Callisto) vary greatly with distance from Jupiter. Satellites of the giant planets that are not in the equatorial plane are thought to be objects captured after most of the proto-planet disk had been dissipated.
Was this article helpful?