To hell with Pluto’s new moons.
Figuratively, of course. But two newly discovered moons orbiting the distant world now have official (and underworldly) names: Kereberos and Styx.
Pluto is pretty small — 2,300 kilometres (1,430 miles) in diameter, smaller than Earth’s Moon — so it may be surprising it has moons at all. But it has gravity, and it can hold on to smaller bodies … and there’s plenty of room out there, billions of kilometres from the Sun, so there’s nothing big enough out there to strip them away, either.
Pluto’s biggest moon is Charon, which is just over half as big as Pluto itself. That’s the biggest moon known relative to its parent world! It was discovered in 1978. In 2005, Hubble observations unveiled two more moons, which were named Nyx and Hydra. A fourth moon, provisionally named P4, was found in 2011 and then P5 in 2012.
Get the trend? All the moons are named after characters associated with the Roman god of Pluto, god of the underworld Hades. Charon was the riverboat driver who brought the dead to Hades. Nix is named after Nyx, the goddess of the night, sometimes depicted as a mist that comes from the underworld. (The name is spelled with an i to avoid confusion with an asteroid with that name.) Hydra was a nine-headed dragon that lived in a cave near the entrance to the underworld (and the nine heads were a sly reference to Pluto being the ninth planet).
Kerberos is the name of the three-headed dog guarding the underworld, usually spelled Cerberus (but again, this name was already taken by an asteroid). Styx was the river separating the underworld from the realm of mortals and also a 1970s rock band. That last bit may be coincidence — via redwolf.newsvine.com