Moons of Pluto moons orbit Pluto at two to four times the distance of Charon, ranging from Styx at 42,700 kilometres to Hydra at 64,800 kilometres from the barycenter of the system. They have nearly circular prograde orbits in the same orbital plane as Charon. All are much smaller than Charon. Nix and Hydra, the two larger, are roughly 42 and 55 kilometers on their longest axis respectively, and Styx and Kerberos are 7 and 12 kilometers respectively. All four are irregularly shaped. The Pluto system is highly compact and largely empty. Moons could potentially orbit Pluto at up to 53% (or 69%,
Dwarf planet recognized five bodies as dwarf planets since 2008: Ceres, Pluto, Eris, Haumea, and Makemake. Ceres and Pluto are known to be dwarf planets through direct observation. Eris is recognized as a dwarf planet because it is more massive than Pluto (measurements by "New Horizons" indicate that Pluto's diameter is larger than that of Eris), whereas Haumea and Makemake qualify based on their absolute magnitudes. In relative distance from the Sun, the five are: Mike Brown considers an additional six trans-Neptunian objects to be "nearly certainly" dwarf planets with diameters at or above 900 kilometers. These objects are: Tancredi et al.