My favorite aspect of the “Pluto is/isn’t a planet” “controversy” is it’s lack of seriousness. From scientists to politicians to most laypeople, whether Pluto is officially classified as a planet, dwarf planet, a KBO, SDO, TNO, Plutoid, or any of a wealth of classifications, isn’t, I think, of much consequence. The controversy is less of a debate than an opportunity to learn more about astronomy.
Nonetheless, I think the controversy would have long been a mere historic curiosity, if 16th century astronomy had moved toward the taxonomological rigor that biology did by the 18th century. The whole Pluto controversy is essentially about nomenclature – naming. We have descriptive, widely accepted terms for Sun-orbiting bodies such as “gas giant planet” that doesn’t “disqualify” its referents from the supercategory of “planets”, but the new “dwarf planet” term seems to be taken as in some sense derogatory. Why gas giant planets are considered planets, but dwarf planets not, strikes me as an twist of language and psychology. I’m puzzled that most people don’t share DougF’s opinion:
Quote:
Originally Posted by DougF
I think a 'dwarf planet' should be considered a 'planet?'
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Perhaps the
IAU definition of “planet” would have fared better with astronomers and the public at large if it had promoted an multi-word term like “orbit clearing planet” rather than restricting the definition of the canonic term “planet”. “The Solar System has only eight
orbit-clearing planets” strikes me as less provocative than “The Solar System has only eight planets”.
Methinks maybe the roots of the controversy go back much further, to the unfortunate
Copernican revolutionary choice to acknowledge the similar nature of the Earth and five other known Sun-orbiting bodies by terming them all “planets”. Planet, most of us know, is a
Greek word for “wanderer”, descriptive of their irregular motion as viewed in the Earth’s sky. Terming Earth a “wanderer” was somewhat analogous to acknowledging the anatomical kinship between humans and birds by calling humans birds.
We could, therefore, reclaim the old, old school definition of “planet” as an object visible with the naked eye that moves relative to the stars. We’d then have somewhere from five to ten or so, depending on whether the Moon (or even the Sun) is included, and whether object that an extraordinarily sharp-eyed person can detect given precise directions where to look. By this definition, +5.4
visible magnitude Vesta is a planet, while +5.5 Uranus might not be, and +7.8 magnitude Neptune certainly isn’t. +13.7 magnitude Pluto – forgettaboutit.
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The naming controversy - origin and cures(?)
