Called Quaoar ("KWAH-o-ar") -- a native American word for the creative force -- the object resides in the vast Kuiper belt region of space beyond the orbit of Neptune, where astronomers think some of the leftover materials of the solar system are located. Most astronomers think Pluto itself is a Kuiper belt object that was bumped into its oddly inclined, Neptune-crossing orbit by a collision.
"If Pluto were discovered today, no one would even consider calling it a planet because it's clearly a Kuiper belt object," said California Institute of Technology's Michael Brown, who, along with post-doctoral researcher Chad Trujillo, announced the discovery of Quaoar at an American Astronomical Society meeting in Birmingham.
The scientists first found the object in digital sky survey taken in June by the 48-inch Oschin Telescope at the Palomar Observatory near San Diego. The object then was found in archival images as far back as 1982 and in July and August, Brown was given time on the Hubble Space Telescope to verify the discovery.
"It was fun, of course, seeing it there in the discovery image," Trujillo said in an interview with United Press International, "but it was also a little disappointing because we wanted to find the largest object there is -- something bigger than Pluto."
The team is still early in its efforts. Quaoar, which is about 800 miles in diameter, was found after studies of just 7 percent of the sky.
"I think the day will come when we find something larger than Pluto," said Trujillo.
The international agency charged classifying planets briefly considered demoting Pluto to a minor planet status, but decided in 1999 against making any changes.
The American Museum of Natural History's Hayden Planetarium in New York City decided to abandon the idea of counting planets and instead groups the objects by common characteristics, such as rocky-core or gas giants. In its new exhibit, Pluto become king of the Kuiper belt region, as opposed to the puniest planet in the solar system.
"There's no science in counting planets," said Neil de Grasse Tyson, Hayden Planetarium director. "The word has lost all utility. Classification concepts need to flow with the discoveries of our times. If not they become handcuffs to the past."
(Reported by Irene Brown, UPI Science News, at Cape Canaveral, Fla.)