Whew! Pluto IS a planet

From Yahoo News:

Opponents of Pluto, which was named a planet in 1930, still mightspoil for a fight. Earth’s moon is larger; so is 2003 UB313 (Xena),about 70 miles wider.

But the IAU said Pluto meets its proposed new definition of aplanet: any round object larger than 800 kilometers (nearly 500 miles)in diameter that orbits the sun and has a mass roughly one-12,000ththat of Earth. Moons and asteroids will make the grade if they meetthose basic tests.

Roundness is key, experts said, because it indicates an object hasenough self-gravity to pull itself into a spherical shape. Yet Earth’smoon wouldn’t qualify because the two bodies’ common center of gravitylies below the surface of the Earth.

“People were probably wondering: If they take away Pluto, is RhodeIsland next?” Binzel quipped. “There are as many opinions about Plutoas there are astronomers. But Pluto has gravity on its side. By thephysics of our proposed definition, Pluto makes it by a long shot.”