|Pluto's humiliation continues. Last month, the International Astronomical Union (IAU) officially stripped it of planet status, calling it a "dwarf planet" instead. This month, the Minor Planet Center (MPC) gave it a new, additional name: asteroid number 134340. The move is in keeping with poor Pluto's slide to something short of a planet. Pluto's moons--Charon, Nix, and Hydra--will be called 134340 I, II, and III, respectively.|
Meanwhile, the celestial body that, in the end, provoked Pluto's demotion got its official name. The IAU announced that 2003 UB 313, nicknamed "Xena," will be called Eris, after the Greek goddess of discord and strife. Eris's moon will be called Dysnomia, after Eris's daughter, the spirit of lawlessness. Eris is slightly larger than Pluto, and three times farther from the sun. According to the IAU's new definition of "planet," it's a dwarf planet, too--not the real deal--because it hasn't "cleared the neighborhood around its orbit."
By the way, that definition hasn't exactly met with widespread acceptance. In the weeks following its announcement, many astronomers have called it "sloppy science" and have claimed that "it won't stand." They point out that few planets ever fully "clear the neighborhood" around their orbits. After all, said one, "If Neptune had cleared its zone, Pluto wouldn't be there," because Pluto's orbit sometimes crosses Neptune's.
In fact, hundreds of astronomers have signed a petition stating, "We, as planetary scientists and astronomers, do not agree with the IAU's definition of a planet, nor will we use it. A better definition is needed." Stay tuned. The IAU doesn't meet again until 2009, so we're probably in for three years of interplanetary war.
September 19, 2006
Knowledge News reports how the recent degradation of Pluto's status continues:
Posted by Mike at 9/19/2006