Rocky and giant and dwarf ... oh my!

I refer, of course, to the current official categorization scheme for planets -- and what isn't a planet.

(That's not the moon. Earth is only there for scale. Read on.) 

In our solar system the rocky -- or as some prefer to call them, terrestrial -- planets are Earth and its close neighbors: Mercury, Venus, and Mars. The gas-giant planets, of course, are Jupiter, Saturn, Uranus, and Neptune. The dwarf planets -- not really planets --  include Ceres (in the main asteroid belt) and a cast of, probably, hundreds in the Kuiper belt.

It is into that last/new/contentious category that the International Astronomical Union reassigned -- many say, demoted -- Pluto in 2006.

Much has been written about whether Pluto is, or is not, properly a planet. Most of it, IMO, has been silly. I was delighted to encounter a cogent, clear-thinking piece on the topic on Space.com, entitled Fighting for Pluto's Planet Title: Q & A With Planetary Scientist Alan Stern.

The whole interview is well worth reading, but most compelling to me is the observation that rule three of the IAU 3-part definition of a planet -- the rationale by which Pluto was reclassified -- is time- and location-dependent. An apropos quote: "Earth — the one object I think everyone agrees is a planet — is too small to clear Pluto's zone in the age of the solar system, and would not be a planet by the IAU's way of thinking." 

So: let's hear it for Pluto.

And with so many planets, dwarf or otherwise, likely waiting to be discovered in the Kuiper belt, wouldn't Goofy also be a great [dwarf] planet name?  Why shouldn't well-known cartoon characters supplant ever-more-obscure mythological names as the inspiration for celestial bodies?

To all you planetary astronomers out there: here's a list of Warner Brothers toon characters to get those nomination juices flowing ...