Vulcan has disappeared! Mr Spock鈥檚 home world will not give its name to a moon of Pluto, despite the best efforts of Star Trek actor William Shatner.
Instead, the names of Pluto鈥檚 fourth and fifth moons will keep up a Greco-Roman mythological theme tied to the underworld and be called Kerberos, after a three-headed hellhound and Styx, a river in the underworld.
The moons, formally known as P4 and P5, were discovered in 2011 and 2012 by astronomers at the SETI Institute in Mountain View, California. In February, the team asked the public to vote on a list of 12 names taken from Greek and Roman mythology related to Hades and the underworld, in line with Pluto鈥檚 other moons Charon, Nix and Hydra.
Advertisement
Proposals for names were also allowed, and Shatner鈥檚 backing pushed Vulcan, also the Roman god of volcanoes, to a clear lead ahead of the next most popular names, Cerberus and Styx.
The International Astronomical Union has the final say, though. The term Vulcan is already used to refer to hypothetical bodies within the orbit of Mercury, while Cerberus is the name of an asteroid discovered in 1971, hence the decision to go with the Greek spelling, Kerberos.
Danger ahead?
We will get a closer look at Kerberos and Styx in 2015, when NASA鈥檚 New Horizons spacecraft becomes the first to fly through the Pluto system. The craft will make global maps of both Pluto and its largest moon Charon, and it will help determine whether Pluto鈥檚 moons were captured intact or if they formed out of the debris from an impact between Pluto and a similarly sized object 4.6 billion years ago.
鈥淭hat鈥檚 the most commonly accepted formation scenario,鈥� says Hal Weaver of the New Horizons team. 鈥淚t鈥檚 almost like Pluto has a little mini solar system.鈥�
Weaver says there鈥檚 room in the system for other, even smaller moons to exist, something New Horizons could discover when it is a few weeks away from its closest approach.
鈥淚鈥檓 not sure we hope for it, though,鈥� says Weaver. The small moons are probably generating a nebulous ring of dust and pebbles around Pluto as they collide with small meteors moving through the Kuiper belt. New Horizons will have to go through that ring at 14 kilometres per second, and a particle even a millimetre across could destroy it.
鈥淲e think there is less than a 0.3 per cent chance that we鈥檒l strike one,鈥� says Weaver. 鈥淏ut if we found more little moons, especially inside Charon鈥檚 orbit, that would give us pause.鈥�
