New planet definition could demote Pluto
Posted: Wed, Aug 23, 2006, 7:25 AM ET (1125 GMT)
Less than a week after astronomers proposed a definition for the term "planet" that could increase the solar system's total to at least 12, a new definition has emerged that could not only eliminate the three new planets but also the ninth planet, Pluto. After a contentious meeting Tuesday at the International Astronomical Union meeting in Prague Tuesday, astronomers came up with a revised definition for the term planet. The original proposal required planets to be orbiting a star (and not be in orbit around another planet) and be "nearly" round; the new definition retains those rules but adds that the planet be the "dominant object in its local population zone". Worlds that meet the first two criteria, but not the third—such as Pluto and Ceres—would instead be classified as "dwarf planets". IAU members are scheduled to vote on the proposed definition on Thursday.
Less than a week after astronomers proposed a definition for the term "planet" that could increase the solar system's total to at least 12, a new definition has emerged that could not only eliminate the three new planets but also the ninth planet, Pluto. After a contentious meeting Tuesday at the International Astronomical Union meeting in Prague Tuesday, astronomers came up with a revised definition for the term planet. The original proposal required planets to be orbiting a star (and not be in orbit around another planet) and be "nearly" round; the new definition retains those rules but adds that the planet be the "dominant object in its local population zone". Worlds that meet the first two criteria, but not the third—such as Pluto and Ceres—would instead be classified as "dwarf planets". IAU members are scheduled to vote on the proposed definition on Thursday.
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