The internet has spoken. With the rolling thunder of a half-million keyboards clickity-clacking in unison, the name "Vulcan" was far and away the big winner in the International Astronomical Union (IAU)'s Pluto Rocks! campaign to christen the dwarf planet's two recently discovered moons — P4 and P5 — with new, unscientific names.
But it appears the IAU has its own ideas, choosing to spurn the people's choice by naming the moons "Kerberos" and "Styx," which came in second and third in the voting, respectively.
To ancient Romans, Vulcan was the God of fire, typically depicted with a blacksmith's hammer. You may know him by his Greek name, Hephaestus. And to Trekkies of the modern era, Vulcan is the name of Spock's home planet in Star Trek — which is probably why the name shot to the top of the polls.
According to BBC News, "The IAU opted not to use it, on the grounds that it has been used elsewhere in astronomy and not sufficiently associated in mythology with Pluto, the ruler of the underworld."
The IAU stressed that the name has already been used before:
[T]he name Vulcan had already been used for a hypothetical planet between Mercury and the Sun. Although this planet was found not to exist, the term "vulcanoid" remains attached to any asteroid existing inside the orbit of Mercury, and the name Vulcan could not be accepted for one of Pluto's satellites. [IAU]
Kerberos and Styx join Pluto's three other moons, Charon (the being that brings souls to the underworld), Nix (the goddess of night), and Hydra (a nine-headed serpent) to form one of our solar system's more interesting satellite systems. In Greek myth, Kerberos (also referred to as Cerberus) is the snarling, three-headed dog that guards the entrance to Hades, and Styx is the mythical river that separates the living from the dead. It is also this: