And Then There Were Eight

After the last Blog entry on the subject of planets, I got quite a bit of feedback on my opinion; most of it negative. How to define what a planet was, based on conformance to the ecliptic plane, or on any determination other than 'roundness' turned out to be more problematic than I at first thought. I finally came to the conclusion that what was needed was a distinction between belt objects that were round (I suggested the name 'planetoid' several times) and planets, rather than the other way around.

This is a lot like trying to define the word table, and coming up with a definition that fits what most people think of when they hear the word 'table'. When I think planet, I can see virtually airless Mercury with no satellites on one end of the scale, and Jupiter the gas giant with it's many moons on the other end. But what do they all have in common other than roundness? Gravitational dominance of their region of space, that is the other property that makes them planets. It's what originally disqualified Ceres and her sisters in the asteroid belt. It's why Pluto isn't a planet way out in the Kuiper belt. The objects trapped in the Lagrange points defined by the planets just confirms this.

Imagine my surprise when I heard the news from the IAU. Pluto is no longer a planet, and the qualification for the IAU to consider a round stellar object a planet is that it must have “cleared it's neighborhood”. I don't care much for the wording used, but it seems to communicate the intent reasonably well. I'm on the winning side, for once.

Which makes me uneasy. I generally adhere to the observation “If you find yourself holding a majority opinion, check your assumptions”. Majorities are very rarely right, contrary to popular opinion. I was a little mollified when I discovered that the voting was limited to 424 out of a possible 10,000 members, so the majority that carried the vote is anything but. Still, it's no different than the average city council race where more than half the population doesn't even know it's election day, much less bothers to vote. They still call it a win, why shouldn't I?

Does any of this have any effect on the newly dubbed dwarf planet Pluto? No, it's still spinning out in space, with it's (at last count) three satellites. You wouldn't think so to hear some of the arguments coming from the dissenters to the decision. Words like 'farce'. Why shouldn't a professional community be allowed to determine the definitions for the words that they will use within their profession? Definitions in common use will remain calmly oblivious to whatever the ultimate outcome of the current astronomical dust-up is. The same majority usage that assigns definitions to words like 'table' will dominate the literary landscape, no matter what those of higher learning would prefer in the end.

Here's hoping that some future child peering out a porthole in his parents' family owned business/home (which also happens to be a spacecraft) will learn the correct usage of the word from a more knowledgeable parent.

“Hey, dad! Is that the planet Ceres?”

“Sorry son, Ceres isn't really a planet. That's why we have to dodge all these other rocks out here...”

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