Pluto also has four tiny moons.
Styx (Charon was the ferryman who took the dead over the river Styx to the Underworld)
Place names will be based on river gods.
Nix (Goddess of the night, mother of Charon)
Place names to be based on deities of the night.
Kerberos (Three-headed dog guarding the entrance to the Underworld)
Place names based on names of dogs from literature, mythology and history.
Hydra (Multi-headed serpent whose lair was a lake under which was an entrance to the Underworld)
Legendary serpents and dragons.
Voting ends on April 7.