Re: "Pluto Now Called a Plutoid"

Erik Max Francis wrote:
Bryan Derksen wrote:
So clearly these are not what the IAU had in mind. Where did these come from? Or did you just make them up on the spot?

The point is, there are an _infinite_ number of possible quantifications. Anyone could come up with some that they think are useful or not. You could argue that this is part of what the Bode-Titius law is.

And yet most of those possible quantifications are not what professional astronomers would likely consider to be good ones, putting it mildly. You still haven't mentioned where you got those examples you gave, I presume you made them up yourself. That's not going to be particularly representative of the scientific consensus.

Citing papers, on the other hand, is a good way to get an idea of what professional astronomers think on the subject.

The fundamental point here, which you're skipping over, is the IAU has never said what they mean.

And for some reason that you haven't explained you're assuming that they meant something dumb.

I guess I just see no reason not to give them the benefit of the doubt.

In fact, I would doubt very much that there was a quantifiable definition that they had in mind. As I've said, all the IAU's ultimate declaration is basically a paragraph of, "Planets are big, round, and gravitationally influential on bodies around them." That much is blatantly obvious and was _already_ the de facto "definition" of a planet, for those who've tried to come up with generalizations to, say, other planetary systems, as we've seen many times over the years.

If that was the de facto definition already then Pluto was already off the list and it just hadn't been officialized yet. Pluto is not particularly influential over the bodies around it.

If you accept that I'm not even sure what you're arguing about any more. Would you have preferred that the IAU simply release an updated list of planets with Pluto struck off of it, without explaining why? I somehow doubt that would have been better received.

Definitions of planet clearing had been previously published. The members of the IAU who voted on this resolution are, generally speaking, well-read on such matters. I don't see any reason to assume they didn't have those definitions in mind, especially since they give the same results as the IAU's unspoken definition.

That those papers exist doesn't mean that ~400 people who voted on that resolution (not voted to accept; voted total) were specifically familiar with them in detail. In fact, I'd seriously doubt that they were, as I've said above (and before), the IAU's resolution proposal was nothing more than common sense: namely, that planets tend to clear out other, smaller objects from their orbits.

Perhaps most of them hadn't read those specific papers (and perhaps they had, I don't know for sure and neither do you). But they are a decent way of estimating what the general attitude among astronomers was. Do you know of any other papers on the subject that suggested alternative methods of classification?

Remember, the only person linking the IAU's non-specific resolution with those particular papers is _you_.

Hardly. I don't read those journals, I only came to them when I read up on stuff written by other people about the IAU's resolution.

There was no Kuiper "cliff." The previous IAU definition was merely a
> list; the IAU would have to specifically _add_ objects to the list for
> them to qualify, and there was zero risk of this happening at any
> point. This is simply a false slippery slope argument.

No, it's real:
http://en.wikipedia.org/wiki/Kuiper_belt#.22Kuiper_cliff.22

There could be Mars-sized or Earth-sized objects out there in the far reaches of the solar system that are yet to be discovered, and continuing to rely on an arbitrary list-based definition at that point would be silly. You'd have to have the IAU debate over each one with no explicit common basis amongst the debators for what they were actually arguing about.
.

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