JUST POSTED ON TAP ONLINE: FEAR OF A NINTH PLANET.

Astronomy, clearly, had been progressing just fine in previous decades without a rigorous definition of �planet.� Telescopes, NASA-launched probes, and other instruments were bringing us more and more information about which objects exist in the solar system and about the nature of those objects. The term �planet� meanwhile, had long since ceased to play a substantive role in the science of astronomy. Before Copernicus, celestial bodies were divided between the planets (the moon, Mercury, the sun, Jupiter, etc.), which moved, and the stars, which didn�t. Contemporary astronomy, however, distinguishes among objects according to what they�re made of, so that the sun is a star and so forth. The very notion of a planet is, at this point, a piece of folk culture, not an important element of science. And according to cultural tradition, there are nine planets and Pluto is one of them.

There neither was nor is any need for busybody scientists to gin up a rigorous definition and then tell us Pluto doesn�t make the cut. It would be akin to gathering a giant conference to decide on a formal distinction between �bugs� and other small, gross animals. If we include worms do we need to include slugs? If we have slugs, then what about snails? And did you know that round worms (nematodes) are no more closely related to segmented worms (annelids) than they are to humans (chordates)? Well, I learned it about a year ago and suffice it say that I still use the word �worm� despite its lack of solid scientific backing. The world is getting on just fine.

--The Editors