Solar System Redefined

Just as in the Bible Adam achieved dominion over the objects of the earth by naming them, so scientists partly establish human dominion over the cosmos by naming or classifying all things animal, vegetable, or mineral.

At a meeting of the International Astronomical Union (IAU) last week in Prague, the system of naming planets was revised, and not everyone was pleased. Hereafter, they declared, there will be eight proper planets and at least three (and probably lots more) dwarf planets. To be a planet an object must be orbiting the sun, must be spherical, and must be big enough to have scarfed up all the matter in its orbital zone.

Pluto, having failed the third of these criteria, is now demoted to being a dwarf planet, and is joined in that category by two other objects, Ceres and Xena (whose official name is still 2003UB).