to read more about how it works: Formation of Regular Satellites from Ancient Massive Rings in the Solar System
in the abstract : "massive rings disappeared [at Uranus and Neptune] to give birth to most of their regular satellites. When the spreading is fast, only one large satellite forms, as was the case for Pluto and Earth."
in the abstract : "massive rings disappeared [at Uranus and Neptune] to give birth to most of their regular satellites. When the spreading is fast, only one large satellite forms, as was the case for Pluto and Earth."


