Dinky Pluto Loses Its Status As Planet

In this image provided by NASA Feb. 22, 2006 from NASA's Hubble Space Telescope shows two new moons around Pluto. Leading astronomers Thursday Aug. 24, 2006 stripped Pluto of the planetary status it has held since its discovery in 1930. Pluto is in the center and Charon, the largest of Pluto's three moons, is just below it. Charon is no longer under consideration for any special designation. (AP Photo/NASA) (AP)

NASA said Pluto's downgrade would not affect its $700 million New Horizons spacecraft mission, which this year began a 9 1/2-year journey to the oddball object to unearth more of its secrets.

But mission head Alan Stern said he was "embarrassed" by Pluto's undoing and predicted that Thursday's vote would not end the debate. Although 2,500 astronomers from 75 nations attended the conference, only about 300 showed up to vote.

"It's a sloppy definition. It's bad science," he said. "It ain't over."

The shift also poses a challenge to the world's teachers, who will have to scramble to alter lesson plans just as schools open for the fall term.

"We will adapt our teaching to explain the new categories," said Neil Crumpton, who teaches science at a high school north of London. "It will all take some explanation, but it is really just a reclassification and I can't see that it will cause any problems. Science is an evolving subject and always will be."

Under the new rules, two of the three objects that came tantalizingly close to planethood will join Pluto as dwarfs: the asteroid Ceres, which was a planet in the 1800s before it got demoted, and 2003 UB313, an icy object slightly larger than Pluto whose discoverer, Michael Brown of the California Institute of Technology, has nicknamed "Xena." The third object, Pluto's largest moon, Charon, isn't in line for any special designation.

Brown, whose Xena find rekindled calls for Pluto's demise because it showed it isn't nearly as unique as it once seemed, waxed philosophical.

"Eight is enough," he said, jokingly adding: "I may go down in history as the guy who killed Pluto."

Demoting the icy orb named for the Roman god of the underworld isn't personal _ it's just business _ said Jack Horkheimer, director of the Miami Space Transit Planetarium and host of the PBS show "Star Gazer."

"It's like an amicable divorce," he said. "The legal status has changed but the person really hasn't. It's just single again."

___

AP Science Writers Alicia Chang in Los Angeles and Seth Borenstein in Washington, and correspondents Sue Leeman in London and Mike Schneider in Cape Canaveral, Fla., contributed to this story.

___

On the Net:

International Astronomical Union, http://www.iau.org