The International Astronomical Union (IAU) has spoken and christened Pluto’s newest and tiniest moons Kerberos and Styx. Maybe you cast a vote in the informal Pluto moon naming contest in February and hoped that the number one choice Vulcan, home of Mr. Spock in the Star Trek TV series, deserved a chance.
Sorry to disappoint, but in a moment you’ll see why that hot world doesn’t work for a chilly planet on the solar system’s fringe. Hint, hint.
The moons were picked up during a survey of the Pluto system with the Hubble Space Telescope in 2011 and 2012. Kerberos’ diameter is somewhere between 8 and 21 miles (13-34 km); Styx is even smaller at 6-15 miles (10-25 km). In early 2013 Mark Showalter, senior space research scientist at the SETI Institute, wanted the public to be involved in the naming of the new moons, so he started a contest.
To be consistent with the names of the other Plutonian satellites, they had to be picked from classical mythology and reference the mythological underworld where souls traveled in the afterlife. Pluto’s deep, dark location has always given it underworld credentials.
None other than William Shatner himself, a.k.a. Captain Kirk from Star Trek, suggested Vulcan. The response was overwhelming with almost 500,000 votes and 30,000 write-ins. When the votes were tallied Vulcan handily took 1st place followed by Cerberus and Styx. Cerberus was changed to Kerberos, the Greek spelling of the word, to avoid confusion with the asteroid 1865 Cerberus.
Styx fit perfectly since this goddess ruled over the underworld river of the same name. Likewise Cerberus, the multi-headed dog that guarded the entrance to the underworld. But what about Vulcan? As the ancient Roman god of fire there’s no question about its mythological pedigree, but the IAU had some issues.
First, Vulcan had already been used as the name of a hypothetical planet 19th century astronomers hoped to find between the orbit of Mercury and the sun. Second, the current term ‘vulcanoids’ refers to hypothetical asteroids that orbit inside the orbit of Mercury. Finally, Vulcan simply doesn’t fit the underworld scheme.
You can’t get EVERYTHING you want. Showalter is “grateful to the IAU for giving such careful consideration” to the public’s suggestions. I’m thrilled that we can finally address all members of Pluto’s family by their first name.