There Goes the Solar System

A committee of the International Astronomical Union, the body responsible for the naming of planets and other celestial objects, has decided to allow at least three new “planets” into the solar system.  The group made the recommendation after it was asked to resolve the Pluto controversy.

Pluto, once thought to be much larger in size, is actually smaller than a nearby non-planet.  With scientists discovering more and more “planetoids,” debate has been raging among astronomers over what objects deserve the name of planet.  Some scholars insisted Pluto should be removed from the category entirely, while others applauded the new system.

BBC News:

The IAU draft resolution recognises eight “classical” planets - Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune - three “plutons” - Pluto, Charon and UB313 - and the asteroid Ceres.

Charon is currently described as a moon of Pluto, but because of its size some experts consider it a twin planet.

Professor Owen Gingerich, who chairs the IAU planet definition committee, said: “In a sense we’re demoting Pluto by taking it off the list of classical planets. But we’re promoting it by making it the prototype of this new category of plutons.”

Link

The International Astronomical Union/Martin Kornmesser