Tuesday, November 23, 2010

Pluto's Status Changes Once again.

Tim Sayell writes -First is one, then it's not....then it is one...then it's not... You know what I think? I think two scientists in white coats find an empty observatory somewhere and just flip a coin...
Anyway, Pluto might be a planet again.

Well that might be a bit hasty, but according to the Yahoo News article that Tim sent in Pluto has become the largest body in the outer solar system. It seems that with further observation, Eris (the body that caused all this trouble with Pluto.) has had it's size placed at somewhat smaller than Pluto. Not by much mind you, they are so close as to be almost the same size. That is precisely what makes many astronomers uncomfortable. With the discovery of Eris, it became clear that the outer reaches of the Solar System contain many Pluto class bodies. If Pluto was a planet then the very real possibility arose that instead of nine planets we would have literally hundreds of them. If Eris was not a planet then smaller Pluto could not be one either.

It makes sense. The smallest recognized planet in the inner system is Mercury which is only 3,000 miles in diameter, Pluto is less than half that at about 1400 miles. Also all the inner planets have basically circular orbits all in the same plane. Kuiper objects like Pluto and Eris have eccentric orbits that are tilted to the normal planetary plane.

But it is not only size that determines a planet. One of the criteria says that a planet must be able to clear all other bodies in it's orbital plane. All the planets out to Neptune have done just that. The thing is that as you move away from the sun your orbit becomes much larger. It becomes much harder, only gas giants are capable of the job that far away from Sol. The curious thing is, according to the Yahoo article, that if Earth were moved to Pluto's orbit, it could not clear it's orbit and therefor would not be a planet, which is clearly ridiculous.

So the argument still goes on it would seem. Check out the article at Yahoo News for the pros and cons of Pluto's planethood. HERE

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