Astronomers Claim Discovery of 10th Planet

30 July 2005 | 08:05 Code : 5461 Geoscience events
Astronomers announced Friday that they have discovered a new planet larger than Pluto in orbit around the sun.
Astronomers announced Friday that they have discovered a new planet larger than Pluto in orbit around the sun. The finding will likely renew debate over what exactly is a planet and whether Pluto should keep its status.
   The unnamed object — the farthest-known object in the solar system — is currently 9 billion miles away from the sun, or about three times Pluto's current distance from the sun. Astronomers do not know its exact size, but its brightness shows that it is at least as large as Pluto and could be up to 1 1/2 times bigger.
   "This is the first object to be confirmed to be larger than Pluto in the outer solar system," Michael Brown, a planetary scientist at the California Institute of Technology, said in a telephone briefing.
   The briefing was hastily arranged after Brown received word that a secure Web site containing the discovery was hacked and the hacker threatened to release the information.
   Brown labeled the object as a 10th planet, but there are scientists who dispute the classification of Pluto as such. There is no official definition for a planet and setting standards like size limits or orbital patterns potentially invites other objects to take the "planet" label.
   Brown and colleagues Chad Trujillo of the Gemini Observatory and David Rabinowitz of Yale University first photographed the object in 2003 using a 48-inch telescope at the Palomar Observatory. But it was so far away that its motion was not detected until data was analyzed again this past January. It will take at least six months before astronomers can determine its exact size.
   The new planet is rocky and icy, similar to Pluto, and is the third brightest object located in the Kuiper belt, a disc of icy debris beyond the orbit of Neptune, Brown said.
   It has taken scientists this long to find the planet because its orbit is at an angle compared to the orbits of most planets.
   Alan Stern of the Southwestern Research Institute in Boulder, Colo., said he was not surprised by the discovery since other objects around the size of Pluto have been found in the Kuiper Belt. What's unique about the latest finding is that the object appears to be bigger than Pluto, he said.
   "Unless they've made a grave mistake, this is for real," said Stern, who had no role in the discovery.
   On Thursday, another group of astronomers claimed that they found a bright object beyond Neptune, but it turned out to be smaller than Pluto. Brown said his group also found another object that was also brighter but smaller than Pluto.
   Brown has submitted a name for the new planet to the International Astronomical Union, which has yet to act on the proposal. He did not release the proposed name.


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