16 August 2006

Anyone can be a planet these days...

It seems everyone is weighing in on the debate about whether Pluto and other Kuiper Belt Objects are planets or not.

CBC Story on New Planets

Ok, I've always been a Pluto detractor ever since it came to light that Pluto was just a very large Kuiper Belt object, one of about a dozen known in fact (and possibly dozens, hundreds, thousands, or millions more, we just don't know), and is actual smaller than Xena. The only reason it was a planet while the others were not was that Pluto is in the near side of the Kuiper Belt while the others are much deeper into the belt, thus it could be seen easier.

But the IAU said Pluto meets its proposed new definition of a planet: any round object larger than 800 kilometres in diameter that orbits the sun and has a mass roughly one-12,000th that of Earth. Moons and asteroids will make the grade if they meet those basic tests.

I think this is dumb. Pluto is smaller than most moons, and is part of a belt of similar objects. I just don't like that. Same goes for Ceres in the asteroid belt. However, based on the new size and gravity criteria (sphericality is key, which isn't a bad way of defining it), then they'd count, along with Xena. Fine, I can accept that large Kuiper Belt objects can be considered planets. But now they're also talking of adding Charon, a pathetic little runt of a satellite, simply because the fact that its planet is a little runt itself qualifies it as a double planet system. Actually, that's not quite right; it's worse than that. They are basing it on whether the centre-of-gravity is beneath the primary's surface or not, so simply having a satellite be far away is enough to have it called a planet. Ugh. So TWO planets instead of zero planets.

Anyway, my proposal would be the same as the IAU proposal with the following excections:
1) Double planets are not based on CoG, simply that the secondary planet is some arbitrary percentage of the primary's mass (say, 85%),
2) Any object staying within it's original debris field is not a planet (bye-bye Pluto, Charon, Xena, and Ceres)

I know this is all just semantics, and it doesn't really matter. I'm just saying, if you're going to redefine something, it's easier to remove Pluto with white-out than to add a bunch of new planets into the textbooks.

Forgive the half-baked thoughts. Just unreasonably pissed about the whole thing...

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