Aug. 15, 2006 — Scientists have to agree on a universal definition for what qualifies as a planet, the head of a global astronomy organization said Tuesday, as scientists debate the future designation of Pluto.
"People have to be able to agree on a terminology that's used to describe things in the universe," Ronald D. Ekers, president of the International Astronomical Union, told reporters in Prague.
"We don't want an American version, a European version and a Japanese version."
Ekers made his comments on the sidelines of a meeting of nearly 2,500 astronomers from 75 countries. During the 12-day conference, which began Monday, scientists were expected to work on finding an internationally accepted definition of what constitutes a planet, and decide whether Pluto should keep its status. Scientists were also expected to consider whether to bring a new planet, nicknamed Xena, into the fold, possibly along with dozens more.
"This particular definition, the definition of a planet, is one that of course has huge public interest," Ekers said.
For decades, most people have defined our solar system as having nine planets, though some have questioned whether Pluto — smaller than Earth's moon — belonged in that category. The discovery last year of an object larger and further away than Pluto has thrown cosmic definitions into chaos.
Until now, there have been no definitive criteria, with most simply describing a planet as a large, round object that orbits the Sun. Scientists will work on establishing criteria for planet status — including the object's mass, orbit and distance from the Sun — and then whether Pluto and Xena meet the definition.
