One satellite, Kerberos, is far darker than its siblings
NASA, ESA, M. Showalter/SETI Institute
Of Pluto’s five satellites, four — Styx, Nix, Kerberos and Hydra — are packed together about as tightly as possible, researchers report in the June 4 Nature. The four orbits, plus that of the largest moon, Charon, are nearly synced, which suggests that the family formed from debris left behind after something big slammed into Pluto long ago.
Like Jupiter’s four largest moons, the moons of Pluto keep coming back to nearly the same configuration time and time again, the researchers found. Charon completes three orbits, for instance, in roughly the same time Styx loops around once. Since it’s unlikely that all five moons became synced by chance, they probably have a common origin. The tight spacing also indicates that there are probably no other moons or rings lurking among the four smallest moons, since most debris would eventually get snatched by one of those