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Pluto? Who cares? August 29, 2006

Posted by Jorge Candeias in Definition of planet, Pluto.
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One of the things that has surprised me the most in all this debate on what is a planet is the obsession that so many people seem to have with Pluto. I expected it from people who didn’t know about the Solar System much more than the names of the “nine planets”, but the passion so many of the scientists involved, even those that qualified the whole debate as silly, seemed to have about the status of Pluto frankly amazed me. People seemed to decide first if they thought that Pluto was a planet or not and only then chose a definition for planet that placed Pluto where they thought it should be.

In reality, Pluto shouldn’t matter at all. The debate should be centered on what should be the criteria for an object to be qualified as planet regardless of what would happen to Pluto or any other planet in the Solar System or elsewhere. The questions that must be answered are not “is Pluto a planet?”, but “what is a planet?” and “is there any good difference between what’s a planet and what isn’t?” and “of all the things that could be used to set apart planets from non-planets which are the best ones?” It should be only after finding a good answer to these questions that the one about the status of Pluto (or any other planetary object, really) must be answered.

In science, prejudice should not have a place. Whenever it does find its way into scientific theories the result goes from simply wrong to disastrous. We’ve seen it happen over and over again, particularly in human studies, in theories about racial superiority, or about the intrinsic intellectual inferiority of women, or about sexual minorities. But we’ve also seen its nasty work in astronomy, and I’m not talking about those astronomers that were imprisoned or killed by other people, for defending “blasphemous” cosmological theories, for instance, such as Galileo or Copernicus: I’m talking about the astronomers that spent their entire life, or a good portion of it, trying to fit data to their particular pre-conceived ideas on how the universe should work. The great ones, such as Kepler, who spent long years trying to fit planetary movements in circular orbits due to a religious notion that the work of god should result in the perfection of the circle, managed to rise above their prejudice and abandon it at some point. The lesser ones persisted… and were forgotten.

I would like to see Pluto being put aside for a while. I would like to see people discussing the characteristics of the planets regardless of the characteristics of Pluto or its orbit. That would be good science. To decide first if Pluto is a planet or not and only then trying to find a formulation that fits is not.