Pluto No Longer a Planet

It's a dark day for fans of Pluto, the ninth and most distant planet from the sun. Or, rather, former planet.

Today, after days of debating what exactly constitutes a planet, the International Astronomical Union revoked Pluto's planetary status, saying it does not meet the new definition of a planet: "a celestial body that is in orbit around the sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a ... nearly round shape, and has cleared the neighborhood around its orbit." Not to mention Pluto's oblong orbit that sometimes goes within that of Neptune.

Pluto, discovered in 1930, is now bumped to the celestial minor leagues in the category of "dwarf planets," which will include the large asteroid Ceres (which was also once considered a planet) and the newly discovered 2003 UB313 (a.k.a. Xena). It could be worse: the IAU has designated a third, even lesser category called "small solar system bodies" that covers asteroids and comets.

Source: AP (via Yahoo)