WTF? Yeah, that was my reaction too. I seems that the International Astronomical Union is recommending that Pluto remain a "planet". In fact, they recommend that an official astronomical definition of the word planet be adopted:
"A planet is a celestial body that (a) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (b) is in orbit around a star, and is neither a star nor a satellite of a planet."
So, by this definition, Pluto remains a planet and Ceres, the newly discovered Kuiper Belt Object 2003 UB313, and Pluto's moon Charon get a promotion. Now Charon gets a pass on the "is in orbit around a star, and is neither a star nor a satellite of a planet" part because the center of gravity of the Pluto-Charon system is actually outside of Pluto. The Earth's moon is quite a bit larger than Charon (3476km diameter vs. 1212km) but the center of gravity of the Earth-Moon system is beneath the surface of the Earth, so it is considered to orbit the Earth, and thus is not a planet.
To confuse matters more, the asteroid Ceres (now a planet) will be classified as a dwarf planet and Charon/Pluto/UB313 and all the other KBOs and presumably Oort cloud objects that meet the new definition will be called "Plutons" to separate them from the 8 (not counting Ceres) classical planets.
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I'm not cool with Ceres in there. It should be destroyed. As for 2003 UB313, or "yoob" as I like to call it, I say we keep an eye on it and leave "everything on the table" if you know what I mean.
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