[VonDondu]

The traditional view of the solar system--i.e., a star with a few large objects in orbit on a single plane--has already been dismissed for good. Now we know that there are at least 180,000 sizable objects circling the sun and countless dust particles and other small objects. It just isn't a clean, neat diagram anymore.

Resolutions being considered by the group, the official arbiter of heavenly bodies, would define a planet as "a celestial body that is in orbit around the sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a ... nearly round shape, and has cleared the neighborhood around its orbit."

I still see problems with this new definition. The last part about clearing the neighborhood around its orbit helps to clarify the distinction between the "classical planets" (which have supposedly cleared the neighborhood around their orbits) and Pluto (which has many "neighbors" in the Kuiper Belt). But the terminology is very imprecise. For example, what about moons? Can we really say that Jupiter has "cleared the neighborhood around its orbit" when it has at least 63 moons that we know of? Jupiter is surrounded by "neighbors" that it hasn't gobbled up. Saturn, with its famous rings, is even worse. The rings might look like pretty discs from a telescope, but they're actually a mess. What about the Earth itself (gasp) which is gradually losing its own moon (it will no longer circle the Earth in a few billion years)?

Besides, in the case of the inner planets, do they really deserve all the credit for clearing their respective neighborhoods? They never would have made it on their own if they were stuck in the Kuiper Belt. They had so much help from the sun, we're looking at favoritism on an astronomical scale.

On the flip side, doesn't Pluto deserve some credit for capturing a moon of its own? Essentially, Pluto is being discriminated against for being so far away from the sun. I really don't know the answer to this question, but how far away is Pluto's closest neighbor (excluding its own moon like all the other planets get to do, of course)? Is it any closer than the Earth's closest neighbor (not counting the Moon)? Are we saying that Pluto isn't a planet just because some object crosses its orbital path from such a distance that not even Jupiter could snag it up? If that's the case, then a planet's status essentially depends on its location, not merely on its own physical attributes. If you put Venus in the Kuiper Belt, it wouldn't be a planet anymore because there's no way it could ever clear the neighborhood around its new orbit. This definition stinks of cronyism, and I have a problem with it.

I'm not suggesting that we should call Pluto a "planet" just because some people want it to be called a planet or because we have sentimental reasons or because we've called it a "planet" since 1930 and we shouldn't change now. All I'm saying is that the new definition of "planet" leaves a lot to be desired and I would like to see it clarified with better, more precise scientific language.