What's the difference between science and politics?
Normally, I'd say science tends to add to the wealth of the world, while politics detracts. On Thursday, a quasi-quorum of the International Astronomical Union (IAU) gathered in the Czech Republic and demoted the ninth planet from its status as "planet." Pluto is now to be called, uh, a "dwarf planet."
We lost a planet (sorta). What did we gain?
Ever since Clyde Tombaugh discovered Pluto back in 1930, we've been calling the distant, roundish rock a "planet." Tombaugh had continued Percival Lowell's search for "Planet X," the planet suspected to exist beyond Neptune. By sheer trial and error, error and trial, Tombaugh found the itsby-bitsy planet, and the wealth of the solar system seemed to increase by one. Perhaps that's why it was called "Pluto," after the god of wealth. "Hades," that god's other name, means "hidden" or "unseen," also appropriate. But the name "Hades" is associated not with wealth but with that same god's status as the grim ruler of hell. Pluto sounded better.
I think we're all happy with Pluto. (No?)
Since then, a number of new discoveries of bodies in our solar system have cried out for inclusion under the same category. The IAU decided it was high time to have some sort of official definition of "planet" so some rational criteria could be applied to these new objects.
Prior to the conference, most observers were expecting a few new planets, not one less. An initial set of definitions would have upgraded Charon, Pluto's sidekick moon, to planet status, making the two a double planet. To distinguish the smaller icy orbs from gas giants and the Mercury-Mars series of round rocks, the two were to be called "plutons." And so would 2003 UB313, a planetoid slightly larger than Pluto that goes by the nickname "Xena."
But the Warrior Princess got nixed, as did Charon and Pluto itself. These are now categorized as "plutinos" instead of "plutons." A plutino is not, as near as I can make out, another name for "dwarf planet," alas. It means a "trans-Neptunian object" with a certain orbital relationship to the neighboring gas giant. We're left with "dwarf planet" as the more inclusive term for smaller-than-planet. Unfortunately, it begs the whole question: a dwarf planet sounds like a planet to me, just a small one — which means that, contrary to the voting astronomers, there are indeed at least eleven planets in our system. Some say that number could be 24. And it could grow, with more discoveries.