Pluto and three of its moons areshown in a file image provided fromthe Hubble Telescope.
Pluto and three of its moons are shown in a file image provided from the Hubble Telescope. (Associated Press/NASA file)


Astronomers announced a contest Monday to name the two moons of Pluto discovered over the past two years.

Pluto is the Roman equivalent of the Greek Hades, lord of the underworld, and its three bigger moons have related mythological names: Charon, the ferryman of Hades; Nix, for the night goddess; and the multiheaded monster Hydra.


Online voting will last two weeks, ending Feb. 25. Twelve choices are available at Choices include the hero who slew Hydra, Hercules; and Styx, the river to the underworld. As of Monday afternoon, Styx was leading. Write-in name suggestions are welcomed, but they need to come from Greek or Roman mythology and deal with the underworld.