 Kerberos's brightness is only about 10% of that of Nix, and it was only found because the discovery team took eight-minute exposures; earlier observations had used shorter exposures.It was officially designated S/2011 (134340) 1, and was informally referred to as P4.Like Pluto's other moons, it is suspected that Kerberos coalesced from the debris of a massive collision between Pluto and another Kuiper belt object, similar to the giant impact thought to have created the Moon.