[Regulator75]

The IAU is pleased to announce that today it has officially recognized the names Kerberos and Styx for the fourth and fifth moons of Pluto respectively (formerly known as P4 and P5). These names were backed by voters in a recently held popular contest, aimed at allowing the public to suggest names for the two recently discovered moons of the most famous dwarf planet in the Solar System.

The new moons were discovered in 2011 and 2012, during observations of the Pluto system made with the NASA/ESA Hubble Space Telescope Wide Field Camera 3, and increasing the number of known Pluto moons to five. Kerberos lies between the orbits of Nix and Hydra, two bigger moons discovered by Hubble in 2005, and Styx lies between Charon, the innermost and biggest moon, and Nix. Both have circular orbits assumed to be in the plane of the other satellites in the system. Kerberos has an estimated diameter of 13 to 34 kilometres, and Styx is thought to be irregular in shape and is 10 to 25 kilometres across.

http://www.iau.org/public_press/news/detail/iau1303/