SPACE NEWS
August 24, 2006
Pity Poor Pluto
Astronomers decide Pluto is not a planet
 This photo taken by the Hubble Space Station shows Pluto (center), and its three moons. |
Poor, puny Pluto. After it was discovered in 1930, it basked in the glory of being named the ninth planet in our solar system. But in the years since, astronomers have debated whether Pluto truly is a planet. After all, it is smaller than other planets, has a strange tilt and travels in an odd orbit. On Thursday, scientists met in Prague, Czech Republic, to decided Pluto’s fate. The International Astronomical Union voted on guidelines that define what is and is not a planet. The final answer: Pluto is not a planet!
The Pluto Debate
Some 2,500 astronomers from 75 countries met in Prague. The planet debate was often spirited and sometimes ugly. Some scientists proposed expanding the number of planets to 12. Pluto, its moon Charon, and two other objects, Xena and Ceres, would be planets. Other astronomers argued that some of the smaller, icy balls should be in a new lesser class of planets called “dwarf planets.”
In the end, the astronomer decided that only Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune fit the definition of “classical planets.” They are celestial bodies in orbit around the sun; they are massive enough that they are nearly round and each planet has its own orbit. Pluto fails to make the grade because its orbit overlaps Neptune’s path.
All is not lost for Pluto. It has been reclassified as a “dwarf planet.” And that’s good news for planet hunters. “Many more Plutos wait to be discovered,” says Richard Binzel, a professor at the Massachusetts Institute of Technology in Cambridge.
