August 23, 2006

Good-bye plutons, hello Plutonian objects

The latest news from Prague is that the International Astronomical Union is now leaning towards demoting Pluto from planethood rather than elevating three new candidates. Also, instead of creating a classification of not-so-planety planets called plutons, the IAU is now considering throwing the sadly downgraded Pluto a bone by declaring it the prototype of a new class of subplanetary bodies. Pluton seems to be out of the running as a name for members of the category, while plutoid and plutonoid are faring no better. The New Scientist reports that Plutonian object is currently the "least unpopular choice." (Quite a ringing endorsement!) Owen Gingerich, chairman of the IAU's Planet Definition Committee, explains, "The purpose of this is to give a nod to those people who are great Pluto fans."

That's right, Pluto fans! You might still get a modicum of respect after all. Don't let the Plutophobes get you down.

(Pluto's proposed new status reminds me of the scene in The Life Aquatic with Steve Zissou where a petulant Klaus interrupts Team Zissou's "lightning strike rescue op" to complain about being relegated to the B Squad. Steve patiently explains, "You might be on B Squad, but you're the B Squad leader!" So Pluto will now get to be the B Squad leader.)

The term pluton is evidently losing out in large part due to the objections of geologists that I discussed in my last post. As Gingerich told Nature, the IAU members did not appreciate that pluton was a common geological term:

Gingerich ... says that they were aware of its usage amongst geologists, but unaware of its importance to the field. "Since the term is not in the MS Word or the WordPerfect spell checkers, we thought it was not that common," Gingerich wrote in an e-mail to The geologic definition of the word does appear in common dictionaries, including the Oxford English.

(Yes, the astronomers really did rely on spellchecker software when assessing pluton. Deutsche Presse-Agentur reports, "One panel member quipped that geologists should attack software-maker Microsoft, not astronomers, for the 'pluton' oversight because the word did not appear in the panel's spellchecker.")

Bucking the anti-pluton sentiment, Gingerich still thinks the two definitions of pluton could happily coexist: "We think words can (and frequently do) have alternative meanings - for example, is there mercury on Mercury?" (To which I'd add: there's definitely earth on Earth.) Despite this sensible argument for polysemy, it looks like pluton is a non-starter.

(See also coverage in the New York Times, which mentions mnemonics that astronomers were devising for the proposed twelve-planet lineup, though sadly there's no mention of Geoff Pullum's attempt. And to satisfy a request from Vili at Vertebrate Silence, here's a suggestion for the Pluto-less arrangement: My Very Excellent Mother Just Sent Us Naugahyde.)

[Update, 8/24/06: Good-bye plutonian objects, hello ... ??? The IAU shot down "plutonian objects" as the name for the new class with the now nonplanetary Pluto as its prototype. Details here.]

Posted by Benjamin Zimmer at August 23, 2006 11:01 AM