Pluto's fourth and fifth moons were named by voters in a lunar naming contest.
The moons, once named P4 and P5, will now be called Kerberos and Styx. The names were submitted by the leader of the team who made the discovery, according to an International Astronomical Union (IAU) press release.
The moons were only discovered recently in 2011 and 2012. Before the new additions were discoverd, Pluto was only known to have three moons.
The IAU is the "arbiter " of the celestial body naming process. The union makes sure the names will work globally, through different languages and cultures so every country can participate in the research without confusion.
Kerberos floats between two larger moons named Nix and Hydra, discovered in 2005. Styx is sandwiched between Charon, (the biggest and closest moon), and Nix.
Mark Showalter of SETI Institute, who led the research team that discovered the moons, called for a public vote on their names.
The winning names were Vulcan, Cerberus and Styx . The proposed names were submitted to the Working Group for Planetary System Nomenclature and the Committee on Small Body Nomenclature for approval.
The first place winner Vulcan couldn't be used because it was the name of a hypothetical planet between Mercury and the Sun. Though this planet was found to be non-existent, asteroids orbiting within the same realm are called "vulcanoids.
The committee accepted the name Styx, and agreed to Cerberus as long as it was converted to the original Greek spelling of "Kerberos" to avoid confusion with a similarly named asteroid.
The only was stipulation was the moons must be named after classic mythology, with some sort of reference to the underworld, in order to stay consistent with Pluto's other lunar objects.
Both of the moons have a circular orbit. Kerberos is believed to be between eight and 21 miles in diameter. Styx is thought to be smaller at only between six and 15 miles and to be irregular in shape.
