Recently two new moons were discovered orbiting Pluto. They were called P4 and P5 (pretty dull). Planetary astronomer Mark Showalter announced a contest on February 13, 2013 where the public was asked to help name the newest discoveries. The named suggested needed to come from Greek mythology.
With the help of Star Trek fans, the most popular name turned out to be Vulcan followed by Cerberus. Vulcan was the Roman god of fire and is a nephew of Pluto. Cerberus was the three-headed hound that guarded the gates to the underworld. Go to http://www.plutorocks.com/to see how the voting came out. For more details about how Vulcan got in the running, click here.
The voting results do not automatically mean that P4 and P5 will end up being called Vulcan and Cerberus. SETI is going to recommend the winning names to the International Astronomical Union — the organization ultimately responsible for naming the moons. While the IAU will take the results into consideration, they have final say over in naming these tiny moons.
Pluto's three bigger moons already had mythological names: Charon, the ferryman of Hades; Nix for the night goddess; and the multi-headed monster Hydra. Charon is almost as large as Pluto, so some astronomers consider them to be a double-planet system.