Planet definition would make 12 in solar system
Hoping to end the agonizing over whether Pluto is really a planet, an international committee of astronomers has come up with a new definition that would save the tiny body’s place in the sun’s family.
Under the long-awaited proposal, Pluto would remain in the pantheon of planets by becoming the prototype of a new sub-category of tiny, outer solar system objects dubbed “plutons” – planets, but distinct from the eight larger “classical” planets closer to the sun.
The changes would require astronomy textbooks to be rewritten and every school child to be taught a new vision of the solar system because three other orbs would get promoted to planet status as well – expanding the total from the traditional nine to 12.
“Everybody’s been wanting to know, ‘Is Pluto a planet?’ ” said Richard Binzel of the Massachusetts Institute of Technology, who served on the seven-member committee assembled by the International Astronomical Union to try to settle the explosive issue. “The answer is: ‘Yes, Virginia, Pluto is a planet.’ “
The proposal to resolve the dispute is being officially unveiled today at the IAU’s General Assembly in Prague, where it will be hotly debated until Aug. 24, when about 1,000 astronomers will vote on it.
The status of Pluto, the smallest of the nine planets, has been called into question by the discovery in recent years of other objects of similar size and distance from the sun. But suggestions that Pluto be demoted prompted heated debate and angry denunciations.
In an attempt to settle the issue, the IAU assembled a 19-member committee, which deadlocked after two years of intensive debate. That led to creation of the smaller committee, which met June 10 and July 1 in Paris to try to find a way out of the thicket.
Under the new definition, a planet would be defined as any body that is massive enough to be round that is not a star but is orbiting one.
Under the definition, the eight “classical” planets would be Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Ceres, an object located between Mars and Jupiter that had long been considered an asteroid, would now be considered a planet.
“One might call it a ‘dwarf planet,’ but that’s not an official term,” Binzel said.
Pluto and another object discovered orbiting it in 1978 called Charon, and a body discovered in 2003 that is slightly farther from the sun, temporarily named UB313, would be plutons. A pluton would be any planet beyond Neptune.