If there is a room full of kids who are offering answers, and after one of them gives the "asphaltic cement" answer and the docent says "Yes -- correct!", the kids who gave other answers before that, without getting the positive feedback, certainly notice.

And my ideals for education are not a one-child = one-subject delineation where the literature/culture kids have to feel like they're on enemy turf in the science museum, where the science-kid gets his "Yes -- correct!"s for a day. If it's because the science kids actually DOES know a fact (like the Sun being bigger than the planets), then that's great. If it's because of a matter of interpretation that someone's going to pretend is a fact, eg, a geologist saying the geographical definition is wrong, then it's a problem.

If a kid who'd been told that Europe was a continent interacted with someone preaching that the tectonic plates determine the continents, telling the kid that he/she is not correct is not appropriate.

And portraying a vote that went one way as an advance in knowledge and a determination of what's correct is also not appropriate. If it were correct in the conventional sense, this debate wouldn't be taking place.

Not got mine yet.

JRehling It is clear that you don't like the IAU telling everyone (public, educators) that their definition is a new "Scientific truth". I think most people on this forum would agree. Its just a definition which is neither true or false, but rather useful or not or esthetic or not—most would agree that IAU's definition is not great, or we would not be having this discussion. However, at times you seem to imply that arrogant scientists are to blame for confusing the public. I don't think this is the case. I think we should allow the possibility of a disconnect of the general definition of a word from the definition most useful to a scientific discipline. Do you agree that scientist should be free to give very specific definition of words for their specialty as long as they don't put out press releases stating that a simple definition is a "TRUTH". I sort of like the very old definition of a planet as anything that wonders relative the distant stars. Children and the public should be made aware of the fact that there are often multiple definitions--I agree that "right answeres" should generally have more qualifications.
Floyd

I'd be happy if this were a situation where a term had a scientific use and a folk use, and never the two did meet. A wonderful example of that is "work", which has a definition in physics and a definition in ordinary life which is quite different. (Except when a laborer hauls things up a hill, and activity which meets both definitions.) Hopefully, no one was ever lectured that their job wasn't work because it failed to meet the physics definition.

However, this "planet" definition has no apparent scientific use, and is being used to *replace* the way the term was previously used. So it's a total strike-out. It doesn't help science, and it does impact the folk audience (kids, laypeople).

And while I agree that a very astute audience (graduate students in the history and philosophy of science) could really sink their teeth into these distinctions, the books I've bought for my son are aimed at an audience that is struggling to understand how a space rock could create a hole in the surface of a planet. Meta-classification is way too abstruse a subject for them. So the discussion doesn't enrich their education. It replaces a small part of it with static. The same way that replacing a small portion of a kid's book about a small country with a paragraph about their bicameral legislature would be static.

Actually, what constitutes a "metal" to a geologist (or an engineer) is quite different to what an astronomer means by that word!

Which, of course, raises the question of what would happen if the geologists' union decided that they had the right to determine the meaning of the word "metal"? Would astronomers thereafter follow the new "official" definition or would they blithely ignore the dictates of the geologists and continue to use their own idiosyncratic version of the word (namely, that every element but hydrogen and helium is a "metal")?

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Stephen

Some kids might get so confused by all of this that they just decide it's not worth learning and give up on the subject altogether. When thinking of education, we need to focus on how to excite kids about astronomy rather than turn them off to it.

Also, regarding the IAU requirement that an object clear its orbit: wouldn't that preclude any binary planetary systems since two planets orbiting one another would not be considered to have "cleared their orbits"?

1) Actually, I think your argument is that any planet definition is useless, and we've already established that this claim is false. I don't know why you keep repeating it. At this point, you need to get a bona fide Planetary Scientist to make that claim, and I don't think you can find one. Failing that, you should drop it.

2) It does occur to me that a word like "planet" is very different from words like "fruit" or "work" in that the general public has no independent experience with planets, so the scientific definition has to be the only definition. Contrast fruit, where the common definition requires it to be sweet (thus excluding the tomato) or work, where the popular and scientific terms only vaguely match. No one is bothered by this conflict, and scientists are free to redefine either term without much notice from the public.

But for "planet" the only defiinition that matters is the scientific one. The public cannot create its own term, since it has no use for it. Some special term for the eight planets the public can actually see with (at most) binoculars probably makes sense, but even that's weak; almost no one is looking.

Planetary Scientists should define to term to suit themselves, and everyone else should accept their definition. They should give some guidance to educators, perhaps along the lines I've suggested, but that's it. It's just not anyone else's business. (Clearly I have drunk Alan's Kool-Aide to the lees.) :-)

3) It does seem clear that the IAU overstepped. Their real message seems to be that they don't want any more "planets," but their actions sinice suggest they're reserving the "cool" names for bodies large enough to be round. That being the case, since their whole role is assigning names, they're unaffected by any serious proposed definition anyway. I'd argue that removes them as a party with a legitimate interest.

--Greg

Well, for it to rise to a "moral issue," I really think it needs to be so bad that it makes the kids kill their teachers (or vice versa), and I don't think we've seen that yet. :-)

As for the "cleared its orbit" definition, I think I see how that can be cleaned up, but I now think that's the wrong way to go.

--Greg

Do also remember that whatever definition of planet upon which we achieve consensus doesn't only need to account for solar system objects. Such a definition ought also to include bodies orbiting other stars.

I can conceive of a lot of solar systems in which major planets have not (yet) cleared their orbital neighborhoods. Young systems, for example, where accretion is *nearly* finished, or older systems where large planets are migrating closer to, or farther away from, their stars. Or systems in which a hot mega-Jupiter, orbiting its star in two or three days, finally spirals in and hits the Roche limit.

Are all of the bodies in such systems not planets because of these circumstances? Does "planet" only and forever describe only eight bodies in orbit around our Sun, disregarding bodies that are already described as "extrasolar planets"?

Or do we need to get better data on other systems to find out just how many adjustments we need to make to *any* definition of planet based only on our experience of our own solar system?

-the other Doug

FYI the word "planet" (which derives from the Ancient Greek for "wanderer"), and the concept behind it, is a very ancient one. It existed long before science was even thought of, and thus long before the true nature of planets was discovered.

In other words, it was the public not the scientists who first noticed the wandering stars in the heavens and who created both the word and the concept behind it for those "stars". Astronomers and other scientists are merely the johnny-come-latelies who are now making the most use of it!

Why then should it be the scientists alone who now decide what that word means? That would look an awful lot like expropriation, IMHO. That is to say, science would have presumptively taken custody of a public word and decided to dictate to that public what that word should mean.

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Stephen

(1)

"We've already established that this claim is false?" Where? I've asked for an example of a scientific use, and none has been supplied. The burden of proof on something that hasn't been demonstrated is not to suppose its existence and ask someone else to prove its nonexistence.


(2)

Tempting, but false observation, that observing the planets is inherently science. Observing the planets is not inherently science any more than looking at Niagara Falls, a snowfall, a map of Belgium, or Playboy magazine is inherently science (geology, meteorology, cartography, and anatomy, respectively). Observing the planets is, by default, the enjoyment of pleasant scenery.

It's certainly true that for Pluto, only someone with a very serious telescope at their disposal can initiate their own observations, but anyone with an Internet connection can go to

http://nssdc.gsfc.nasa.gov/photo_gallery/p...lery-pluto.html

and gaze to their heart's content and see the very same best pictures of Pluto that any expert can. And it's not science to do so.

So I don't think that scientists "own" Pluto any more than they own Mount Fuji.

AOL released the logs of 35 million web searches their users had performed. 1085 of them contain the substring "pluto" but aren't "plutonium" or "plutocracy". Perhaps half of them either explicitly contain "planet" as well or are obviously about the icy body out there. If that same rate applies to other web searches, then there are about 5000 web queries about Pluto every day (in English). I'm betting not very many of those people are scientists. They're treating Pluto, with the tools they have at hand, the same way visitors to the Grand Canyon treat it. There's affection to it, and it's not science.

Good point. Honestly, and I almost gag to say it, but isn't this more of a PR issue than a scientific one?

We have a general category for sure: "things that orbit stars." Other stars doing so are easy to exclude, obviously. Thinking at this general scale, other things...not so much. Debris & leftovers from the key stellar formation event, really.

I'm not gonna state a position, just trying to provide another perspective. Maybe a planet is just what we think it is, if you can dig it.

EDIT: Dammit, after some more thought, I do want to state a position. I finally caught the logic behind IAU's current schema. "Minor planets" has long been the categorical definition for asteroids, which was no problem until KBOs came to light. Made sense; they were clearly not comparable to the classical planets.

Pluto was long thought to be possibly Earth-sized throughout much of the 20th Century, but always an anomaly. After 1978, we knew it was only half the diameter of the Moon, but nobody complained; after all, it had a moon of its own. Merely 20 years or so later, it became obvious that there were a host of objects not too different from Pluto in many ways. Then came Quaorar. And Sedna. And, finally, Eris.

Okay. This might work. I propose a new class of objects: "Plutoids" (not to be confused with "Plutinos", which share orbital similarities with Pluto but not other significant properties). Plutoids are objects of Pluto's diameter or better (but not exceeding the diameter of Mercury) that reside in the outer Solar System. They are a class unto themselves, modeled after the minor planet precedent. Anything smaller than the prototypical Plutoid is by definition a lowly KBO; anything larger than Mercury is by definition a planet.

Since I am utterly certain that everyone will accept this construct with tears of joy & starry-eyed admiration for me, my only request is that the Nobel Prize (along with the check) is mailed to me promptly. (Very promptly, if you please, because the rent is due & I don't want to hock more of my shiny metal...) Thank you, and good night!

Yet again, a thread on this topic is getting heated again, despite warnings about it.

After todays debate, the entire issue, and any associate debate, is going, formally, on the banned subject list.

I now have my registration details, so I'm in - and have a question submitted

Yup. Me too. It was pretty tough trying to boil it all down to one concise question.

Anyone else submit one?