The votes are in, and Vulcan won the naming contest for Pluto’s P4 moon. Pluto’s two newest moons, currently named P4 and P5, were discovered in 2011 and 2012 by a team led by SETI chief scientist Dr. Mark Showalter. Such discoverers have the right to recommend names to the International Astronomical Union, who then has final authority on the naming. Showalter and SETI thought it would be fun to solicit votes from the public from a list of 21 names, and the names Vulcan and Cerberus won. The IAU does not reuse names, and since there is already an asteroid named Cerberus, the SETI team plans to submit the Greek spelling of Kerberos instead.
This blog post is a serious pitch to the P4/P5 discovery team and the International Astronomical Union to not assign the name Vulcan to P4, but rather, to save it for the exoplanet Gliese 581 c.
It should be stated up front that the IAU does not currently name exoplanets. But since exoplanets are the fastest-growing field in astronomy, and arguably among those that best capture the public’s imagination, they’re going to have to start doing so very soon. In fact, Dr. Franck Marchis at SETI (@allplanets) says “I think this entire [Vulcan] story should be used to motivate the IAU to finally name exoplanets.”
Reason why P4 deserves the name Vulcan
Some say that in mythology Vulcan was a son of Pluto, so it makes a certain amount of sense for one of Pluto’s moons. But not all that much sense: First, Vulcan was a son of Jupiter and Juno (Zeus and Hera in Greek), not of Pluto; and anyway, none of Pluto’s three already-named moons (Charon, Nix, and Hydra) were children of Pluto either.
Reasons why Gliese 581 c deserves the name Vulcan
Every other reason. Star Trek has, for better or for worse, become an integral influence for today’s astronomy and space programs. People love it. It is broadly beloved internationally. We named the first Space Shuttle after Star Trek’s USS Enterprise (though it never fulfilled its original plan to be converted into a real launchable shuttle). It’s entirely appropriate that we name a real planet after Star Trek’s most famous fictional planet.
Gliese 581 c is an exoplanet orbiting the red dwarf star Gliese 581, discovered in 2010. It shares more characteristics with the fictional Vulcan than any other exoplanet known:
Gliese 581 c
|Hot||Cold X||Hot ✓|
|High gravity||Low gravity (Barely any) X||High gravity (1.6x Earth) ✓|
|Outside the solar system||Inside the solar system X||Outside the solar system ✓|
|In the habitable zone||Outside the habitable zone X||Inside the habitable zone* ✓|
|Has no moon||Is a moon X||Has no known moon ✓|
* Though the planet itself is unlikely to be habitable due to a probable runaway greenhouse effect, similar to Venus. Some early estimates gave it a surface temperature range comparable to Earth, with a possibility of liquid water.
P4 is not even a planet, it’s a moon; moreover, it’s not even a planet’s moon. Pluto is a dwarf planet. Pluto is in our solar system; Vulcan was far away.
We don’t have any sharp images of P4, but it’s almost certainly not round; rather it’s probably just random asteroid shaped. We don’t even know its size for sure; somewhere between 13-34 km diameter. If you were to view it from your comfortable spaceship, you’d say “Wow, that’s a pretty poor excuse for Vulcan.”
Gliese 581 c is a proper, full-fledged planet. It’s rocky, so you can walk around on it. Its gravity is similar to that depicted on the fictional Vulcan, and it has hot temperatures like Vulcan (maybe too hot, but maybe not). In any case, there’s no known better match for Vulcan out there.
Shatner and Nimoy both came out on Twitter in favor of naming P4 Vulcan, and that was fun; but it was probably simply a reaction to Vulcan having been in the running. I doubt either of them, given a choice of heavenly bodies out there, would have agreed that the name Vulcan was best used for a cold, unremarkable, not-even-round rock orbiting a dark dwarf planet.
In a Google Hangout, Dr. Showalter responded to this exact request. “I agree with you, I think Romulus and Vulcan would be great names for exoplanets, and so would all kinds of names out of Star Wars mythology and every other tradition that you can imagine, but I just don’t know if saving a name for an exoplanet is practical when we may never get around to using names for exoplanets.” I argue then, Dr. Showalter, that this is your chance to make a statement. The IAU is well aware that the public really wants the name Vulcan to be used. Don’t submit it for P4.
In my mind, Dr. Marchis treads on a thin rocky crust when he allows for the possibility of re-use. “When we start [naming exoplanets] I don’t think it will be an issue to have a planet named Vulcan and a moon of Pluto named Vulcan as well. The official name of the moon will be ‘(134340) Pluto IV Vulcan’ (or V) if it is accepted by IAU. When we finally have a nomenclature for exoplanet naming, it may be possible to name Gl581c exoplanet: ‘Gl 581 Vulcan c’ or something similar to that.” Hoping for a name re-use is a poor strategy. I don’t envision the IAU naming an exoplanet Jupiter, Titan, Io, Earth, or any other name that’s currently already in use inside the solar system. They may eventually re-use names, but solar system names will be lowest priority for exoplanets; most especially the name Vulcan, arguably the name with the highest public recognition.
So please, Dr. Showalter and friends, and esteemed International Astronomical Union, do not do this rash thing. We will always regret it. Do what’s best for the galaxy: save the name Vulcan for a deserving planet.