Vulcan has been nixed as a name for one of Pluto's two smallest moons.
Although it was the top vote-getter in a February online poll, the International Astronomical Union declined to use Vulcan, the home planet of Mr. Spock in the movie and TV series "Star Trek," as the name for one of Pluto's two smallest moons, previously called P4 and P5.
The IAU is the worldwide organization that establishes names for astronomical objects.
Instead, according to a news release from the SETI Institute in Mountain View, Calif., P4 has been named Kerberos, after the three-headed dog of Greek mythology (spelled Cerberus in Latin). P5 has been named Styx, for the mythological river that separates the world of the living from the realm of the dead.
Kerberos and Styx join Pluto's previously known moons Charon, Nix and Hydra. According to IAU rules, Pluto's moons must be named for characters associated with the underworld of Greek and Roman mythology.
The ballot at plutorocks.seti.org received almost 500,000 votes, including 30,000 write-in suggestions. Vulcan by far received the most votes, totaling nearly 175,000. Half of all votes came from outside the United States.
Kerberos, with more than 99,000, was second in the voting and Styx, with about 88,000, was third.
According to SETI, the IAU gave serious consideration to Vulcan, the Roman god of volcanoes and fire. Because the name already has been used in astronomy, and because the Roman god is not closely associated with Pluto, the proposal was rejected.
Kerberos was discovered in 2011 and Styx in 2012.
Pete Zapadka: email@example.com, 412-263-1857 or on Twitter @pzapadka. First Published July 2, 2013 4:00 AM