Contrary to the new definition the IAU is proposing, which sucks, in my not-so-humble opinion, I’m going to side with Dr. Tyson on this one, and say that Pluto really isn’t a planet. And that further, I think the IAU is caving in to public opinion rather than allowing science to rule the day.

Yes, it’s a semantics issue, but words have meanings, and dammit, semantics are important. And there’s simply no scientific definition of “planet” that allows us to keep the list of planets we’ve come to know and love. None. If approved, the new definition would not only increase the number of “planets” in the solar system to at least twelve, it would also muck with the order. So you can kiss your beloved mnemonic devices goodbye, anyway.

(Side note: I liked the Daily Show’s Colbert’s suggested device the other day: “My Very Educated Mother Just Said “Uh-oh, No Pluto!”)

The truth of the matter is that there’s plenty of evidence that Pluto is a Kuiper belt object (KBO) — basically, a dead comet — and it isn’t even the largest of these, at that. If the IAU membership actually approves this proposed definition, then they’ve essentially said that the opinions of a bunch of third graders are more important than having a coherent, meaningful definition. And that they’d rather cheapen the standard, counting an asteroid and two additional dead comets as “planets,” than admit that they were wrong to have classified Pluto as a planet in the first place.

Sorry, Dawn, but I’m hoping they vote this down.

(Side Note #2: As soon as someone posts tonight’s Colbert appearance by Dr. Tyson on YouTube, I’ll post a link. I’m disappointed that no one has done so already… For now, you can go here and view Pluto Pt. 1 and Pluto Pt. 2)

UPDATE:  Go read Tyson’s 1999 essay on why Pluto should not be counted among the planets.  I think he makes a pretty good case.  Just for spice, Kevin disagrees (although I suspect this is in large part because his wife is hostile to the idea of demoting Pluto, and he values his marriage more than semantics).