Astronomers Pull Rank, Name Pluto’s Moons After the Underworld, Not Star Trek

Say hello to Pluto’s newest moons, Styx and Kerberos

P4 and P5, now Kerberos and Styx. Photo: NASA, ESA, M. Showalter
P4 and P5, now Kerberos and Styx. Photo: NASA, ESA, M. Showalter SETI Institute

A NASA probe, a Canadian starship captain and a group of greybeards have stirred up one of the biggest controversies in astronomy since the now-ex-planet Pluto lost its planetary status.

Almost exactly a year ago astronomers announced that while they were looking for a clear path past Pluto for their New Horizons probe they discovered two new moons orbiting the ex-planet. The planets, temporarily named P4 and P5, were Pluto’s fourth and fifth moons, joining the ranks of Hydra, Charon and Nix.

A few months later, the moons’ discoverer opened a poll—filled with names fitting the Greek underworld theme–asking for people to help vote on Pluto’s moons’ new names. As internet polls tend to go, though, William Shatner (he who played Captain Kirk on Star Trek) hijacked the poll, pitching Vulcan and Romulus as candidates. Romulus was quickly kicked out as it was already in use, but Vulcan went on to sweep the poll.

But the International Astronomical Union, which gets the final say on naming space things, wanted none of these Star Trek shenanigans. Yesterday, the IAU laid down Pluto’s moons’ new names, says the New York Times:

Moon No. 4 is now Kerberos, after the many-headed dog that guarded the entrance to the underworld in Greek mythology. Moon No. 5 is Styx, named for the river that souls had to cross over to get to Hades, or the underworld, and the goddess who ruled over it.

Vulcan failed on two counts: it was already in use (“as the name for a hypothetical planet between Mercury and the Sun”), and it didn’t fit the Greek Underworld theme.

But, recent research suggests Pluto may have as many as 10 more moons just waiting to be discovered. If we put our thinking caps on, maybe we can get a classic sci-fi reference in there…next time.

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