New mnemonic from the IAU?

Majority Vote Ends Matters - Just Shut Up Now!

I didnt vote!

And neither did 96.2% of the IAU's 8900 members: they weren't even allowed to vote if they were
not in Prague. This story is about to break.

Alan: May I ask whether the committee considered the term "planetoid?" It seems it would be very useful to have a single term for bodies large enough to be rounded but not large enough to fuse. A term that's strictly independent of orbital dynamics. Also, I don't believe it already has any formal definition.

Was it just because the term has been overused in science fiction? It seems such an obvious choice I can't believe it didn't come up.

Thats an excellent point I've been thinking about too.

Define "minor".

1) The Caribbean plate contains a large chunk of Central America. Arabia has a plate all of it own. (So does India.) If North America and South America are entitled to be classed as separate continents because they each have their own plate why not those other chunks?

If "the division between India and the rest of Asia" is of "geological significance" why not the divisions between other plates, such as the one between Arabia & the rest of Asia and between the chunk of Central America on the Caribbean plate and the rest of the Americas?

Or is the "geological significance" in India's case those impressively tall mountain its ramming into Asia has managed to push up? If so, what is the "geological significance" of the boundary between the continents of North America and South America?

2) Which raises the related issue of where do you divide North America from South America: at the northern boundary of the South America plate or at the northern boundary of the Caribbean plate? That is, if that chuck of that chunk of Central America on the Caribbean plate is not a separate continent is it part of the continent of South America or part of North America?

3) Then there's the fact that the North American plate includes Greenland and part of eastern Siberia. Does that mean those are part of the North American continent as well (just as Europe, being part of the same plate shared by most of Asia, means that Europe and Asia are part of the same continent under your scenario)?

True, there's all that water in the Bering Strait. However, during the last ice when sea levels were much lower than they are today North America was connected with that chunk of east Asia which is part of the North American plate (just as Tasmania and New Guinea were connected with Australia--although not Australia with Asia--and the British Isles with Europe).

Does that historical connection between East Asia and North America increase the likelihood of that chunk of east Asia making it into part of the continent of North America under your model or does all the water now in the Bering Strait still get in the way?

The point here what kind of boundary marker predominates in your model when deciding where the divisions between continents lie? Geographical ones like water or geological ones like tectonic plate boundaries?

A case in point: you are argue that the "division between Europe and Asia has no geological sigificance". As it happens that division traditionally runs along geographical boundaries such as the Ural Mountains and the Black Sea. If the Black Sea has "no geological significance" as a boundary between Europe and Asia what pray tell is the geological significance of the Bering Strait between Asia and North America?


The reality is that the concept of "continent" was around long before plate tectonics came into vogue. So was the division of Afro-Eurasia into three continents and the American continent into two. Boundaries of "geological significance" have little to do with defining them. Geography and history were used to decide those divisions, not geology.

A continent was and still is basically a large landmass surrounded by water, but with historical considerations tempering the division. (For more, see this Wikipedia page.)

It seems to me you're using plate tectonics in a novel way to try to retroactively justify elements of the historical divisions more than elements of the geographical ones, but in what seems to me to be a potentially inconsistent fashion.

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Stephen

No, not considered by the IAU.

There is aready the horrible-sounding term "planemo" (planetary mass object) which means exactly that.

I've more often seen India and Australia shown as part of the same plate (Indo-Australian plate). Perhaps India and Australia should be reclassified as a "double continent".

[...]

I'm not sure whether this has been mentioned on UMSF yet, but over at Jodcast they have edited down the IAU session which voted on this issue down to a more reasonable 20 minutes or so and put it up as an MP3 on their site. It's about 10MB in size.

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Stephen

It's worse yet -- having just invented dwarf planets, the IAU can't assign names to any of them, because it doesn't have a procedure for naming dwarf planets.

I assume they will appoint a committee to look into ways of handlng the issue. The committee will issue a report no sooner than July 2007; the report will probably recommend the forming of a working group to establish standards and procedures for naming dwarf planets. Those standards and procedures will take a little longer to set up, taking us down to January 2009. At that time a task force can be appointed to implement the procedures. This committee might then begin to produce names in mid-2009, just in time for the IAU Congress in Rio, which will reopen the question and define planet in a totally different way. A special commission will then be appointed to deal with questions of nomenclature...

I think ngunn is right: majority vote ends the matter.
If this was such an important vote, why did not more IAU members attend this decisive meeting, I ask myself. They could have had they wanted to. They didn't and missed out on the chance to bring about a different outcome.
And I do not think it's an unusual thing with such assemblies that you're only allowed to vote if you are there personally. That's the way parliaments of democratic states work as well. The only difference propably is that a certain percentage of members is required to be competent. Is there such a rule for IAU assemblies?

Michael

Uranus' name took decades before it came into common usage.

What's wrong with 2003 UB313? It's easier to remember than some extrasolar planet names, like HD 209458 b. Or 2MASSW J1207334-393254 b.

To be honest, I've waited for the naming of 2003 UB313 and others as much as the planet definition.

[...]

Yes -- but at least there was some name, in fact several, by which astronomers could refer to it. They did not wait around for decades calling it 1781 EN!

Since the IAU will not do it, it's up to us to come up with a provisional name. Following the example of the 18th and 19th century astronomers who wanted to call Uranus "Herschel", and Neptune "Le Verrier", I suggest that 2003 UB313 be called "Brown's Planet", or simply "Brown".

Although, given its very small size, I am sorely tempted to call it "Junior Brown".

"The IAU is composed of 8,858 Individual Members in 85 different countries worldwide out of which 62 are National Members (according to statistics of August 2006)."
--http://www.iau.org/

"Normally, individual members are admitted on the proposal of the National Committee for Astronomy of their home or long-term residence country."
--http://www.iau.org/Application_Procedure.81.0.html

In other words, you don't join the IAU on your own initiative. You have to be invited.

(To be fair that number may be pretty much close to the total number of professional astronomers there are in the world. This page claims: "Professional astronomy is a relatively small field, only about 10,000 individuals being employed worldwide.")

Incidently, for some interesting statistics of where the IAU members come from, see this page. It's especially interesting that the overwhelming proportion--about 87%--are men.

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Stephen

I know, there are always limitations and not everybody who wants to attend can do so. But that applies to both Pluto promoters and demoters, doesn't it? So to argue that the result would have been different had everybody been able to vote is not really valid in my opinion.

Anyway, does anybody know how close the decision was?

Michael

What I heard from the live TV (couldn't get the image), the Resolution 5A had a clear majority supporting it, 5B even greater majority against, 6A was a near-tie with a small majority. 6B failed by only a few votes.

To me, that footnote just piles ridiculousness upon stupidity. First you define "planet" one way, then you turn around and dictate what that means, even if it goes against the definition, giving you the desired result. Totally unprofessional IMHO.

The BBC has an article on the IAU debacle today: Pluto vote hijacked

The article strongly implies that the Pluto opponents manipulated the situation so the vote would take place after most the delegates had gone home. The IAU is not coming out of this looking good in the public media.

On a lighter side, you can buy this bumper sticker now:

Click to view attachment

Profits go to The Planetary Society. I guess we know where they stand on this issue...

From a friend.

It seems that at a recent meeting of the International Beatles Union (IBU), a resolution has been passed changing the definition of "Beatle." Under the new definition, Ringo Starr no longer qualifies as a Beatle, reducing the number of "classic" Beatles to three. Ringo now belongs to a new category designation of "Ringon." The Ringons include Ringo, as well as others previously categorized as minor, or "fifth," Beatles, such as Billy Preston, Harry Nilsson and George Martin.

You want to know how widespread this debacle has become? My wife was surfing through the legal blogosphere and found this post. Scroll down a bit to get to the Pluto part.

Stephen, I think you are missing my point. What I mean is that to define planet as the IAU has would be like saying that we should define continent by a scientific rational while up until now it has been largely cultural. The reason I suggested the lone exclusion of Europe is that, first of all, it is the only continent which doesnt have its own plate associated with it, even if non-majoritarian poritions are composed by other plates, but instead is a minority portion of the plate of which most is considered Asia. So by this criterion, Europe is no longer a continent and is simply a peninsula, but North America and South America, as well as Africa, are still separate continents. The reason that I made the distinction from your earlier post is that this was a criterion that would leave one continent as the "odd man out," as has happened to Pluto, not because this has anything to do with the actual definition of a continent.

Mike Brown's comments.

hmm, a Beatles-related analogy...I wonder

Here is my favorite:

Dog-lovers everywhere shocked to learn of the American Kennel Association's new definition for dog. "With the proliferation of dog breeds in the last 10 years, like the puggle, we felt it was necessary to revisit the issue of what exactly is a dog. We think we have come up with something that works," said Dr. John Matheson, a veternarian from Milwaukee. Under the new definition, a dog must:

1) Must be large enough to hold a tennis ball in its mouth
2) Walk on four legs and bark
3) Have large canine teeth
4) Be carnivorous
5) Be a mammal
6) Cleared out its neighborhood of other objects matching criteria 2, 3, 4, and 5.

The AKA also came up with a new designation: a dwarf dog. These objects matching the following criteria.

1) Must be large enough to hold a tennis ball in its mouth
2) Walk on four legs and bark
3) Have large canine teeth
4) Be carnivorous
5) Be a mammal
6) Have NOT cleared out its neighborhood of other objects matching criteria 2, 3, 4, and 5.

Objects matching these criteria but are not large enough to hold a tennis ball in its mouth will be termed "Small Dog-like Objects". The AKA voters failed to pass a resolution terming these objects rats.

I'm still puzzling over this "neighborhood clearing" business. I'll accept that it doesn't apply to satellites, Trojans, or plutinos which are in one way or another gravitationally controlled by a larger body in their vicinity. But even leaving those out, there are a lot of other things whizzing around in the solar system that don't seem to have gotten the word that they've been "cleared".

I suspect that the really relevant criterion is (once again) one of size: we're talking about objects that are big enough to be repeatedly struck by any of the riffraff in their vicinity and not care; Neptune could probably eat Pluto for lunch and still find itself in mid-afternoon looking for a snack. I'm not sure how that's expressed scientifically.

On the other hand, Pluto is probably big enough to take a pounding from most of the other objects in its vicinity and not be broken up.

The definition seems counterintuitive with regard to a planetary system in the process of forming, where there may be many large objects with potentially intersecting orbits. Presumably, of the two objects whose collision formed the Earth and the Moon, neither could be planets. There may well be extrasolar systems that can be observed to be in the process of forming; will there be one definition of planet for the Solar system, and another for extrasolar systems?

I'm not too big a fan of the neighborhood clearing language either. What you would do with extrasolar systems still forming is a big question. Maybe computer models could be used to try to predict what would happen. The Earth did end up being the dominant body in its area. If you could observe the early solar system, and could make some predictions about what the end result would be, maybe that would mean something. One could also use mass criteria. I think a planet should at least have more mass than all the other objects combined in its area, or possibly even more than that. So, if there's one dominant body in terms of mass, that's the planet. Or, if things are clearly in a lot of flux, you could just call them proto-planets. Who knows!

Let's not forget that parts of California and most of Baja California are on the Pacific Plate. We need to make sure the people on the wrong side of the San Andreas Fault know they are not North Americans!

I actually kind of prefer the nearest neighbor magnification (naturally, only if it's an integral factor of magnification) for this kind of purposes. It makes it clear that it's not adding any new information to the resized image. A smoothly magnified one often can be seen as a blurred image and next thing you know, you've got guys trying to do deconvolution on them and they "find" never-before-seen details...

Click to view attachment

Yes, except that square pixels interfere badly with what you see.

But wait Don, what is that we see when we magnify the image even further???

Click to view attachment

Well, what do you know, Lincoln was a Pluto supporter!

[...]

I just noticed that Mike Brown has written a set of thoughts on the planet debate: http://www.gps.caltech.edu/~mbrown/whatsaplanet/ (apologies if this has already been posted; if so, I missed it.)

In particular, his paper "Planetesimals to Brown Dwarfs: What is a Planet?" http://www.gps.caltech.edu/~mbrown/papers/ps/basribrown.pdf is particularly germane.

Here are two quotes from the latter that seem particularly germane:

"A good definition has several desirable characteristics. It should be succinct and easily understood by the public, yet precise enough to be acceptable to scientists."

"We must accept the fact that, in placing boundaries on a continuum, there might be transitional objects which are quite similar to each other in many respects, yet which are defined to lie on opposite sides of our imposed (and hopefully not too arbitrary) lines. A scientific definition would find natural physical conditions for such boundaries."

So I assume he, like most, is not not happy with the current definition, particularly it's clean neigbourhood clause which is not succinct, not easily understood by the public and fundamentally without precision.

Doug

He favored using Pluto as the yardstick and calling anything that big or bigger a planet -- as long as it orbited a star. He defended it like this:

"This purely culturally based definition is simple and concise. The major flaw in the minds of most astronomers is that there is no science there. Absolutely true. If you feel the need for a scientific definition even though the definition has no affect on science, the answer is clearly that there are eight planets (and, indeed, I have signed on as a supporter of the 8 planet counter-proposal to the IAU). There are other words describing the landscape around us that are equally unscientific, however, and work just fine. The word "continent" is the obvious example. No geologist would ever attempt a scientific definition of the word, and no one in the public seems to mind. Astronomers would be wise to imitate their ground-dwelling colleagues here and not try too hard to rearrange what we call the things that we think of as being in our back yard."

(Complete discussion is under "Astronomers are Revolting!" http://www.gps.caltech.edu/~mbrown/whatsaplanet/revolt.html)

I think that was a mistake to have it on the last day, when most people had already left...those who voted were largely those who were hanging around for THAT issue, and it was the anti-Pluto as a planet crowd that really cared about this. Many things are like that in all walks of life, from other scientific issues to politics to the workplace...extremist points of view tend to dominate because it is the extremists who care more about the issue. Also, most planetary scientists have more important things to do than focus on this debate.

Reading through Mike Brown's pages carefully, the more I think about it, the more I think the 8-planet solution really is the best compromise between the cultural definition and the scientific one(s). Even if the IAU definition needs some work, it certainly seems to be fixable, given that you expect 8 planets. It was trying to somehow keep Pluto but leave out dozens of other KBOs that was impossible. Further, the crispest definition that yields 8 planets will probably be the best one to apply to other solar systems.

Dropping a single planet seems to do less cultural damage than any other scientific proposal. This may be as good as it gets.

The result of an 8 planet solar system is not intrinsically objectionable -- not more than the alternatives, anyway. The criteria devised for privileging 8 planets over 9 or more planets are, however, highly questionable, and nothing is more questionable than the claim that these criteria are the only really scientific ones and that other criteria (with a different result or even the same result) are not. I'm more worried about people coming away thinking that an 8-planet solar system is the only scientifically justified one than with the fact of an 8-planet solar system. An arbitrary mass boundary just at the mass of Mercury would have worked just as well, achieved the same result, been far more intelligible to ordinary people, and would not have absurd pretensions to being "scientific".

I don't see how it's questionable.

The term "planet" clearly includes some sort of "uniqueness" in it. There are eight large objects in the Solar system that clearly are not like each other not only physically, but also they orbit at different distances. It is culturally objectable to accept objects that clearly are "only" the largest members of vast populations of small objects. Even though after it was clear that Pluto is very small and has an odd orbit, it was considered being an individual. When Kuiper belt was finally discovered it clearly became less "planet". Well, of course Pluto is still an "individual" and very much a special object, but it still is a member of the Kuiper belt, something that is not acceptable for a real planet.

The "orbital clearing" part could be considered more like a scientific explanation for the cultural uniqueness.

The resolution is very much a compromise in several directions, it has horrible wording, it doesn't apply or even work for extrasolar planets, but it is a definition after all. I was somewhat surprised that they managed to create a resolution that passed and even more surprised that they had guts to demote Pluto. Even though it was clear that already many did not considered Pluto a real planet.

In my opinion, it is now much more urgent to emphasize the importance of "dwarf planets" to the public than trying to revert Pluto's status. The latter can't be result in anything but ridicule towards astronomers. But the former can result in much better understanding on how Solar system is structured. Already there's more talk about Ceres than probably ever before since its discovery. Don't miss the change to make them known before they're forgotten.

Unfortunately people are political animals. The "dynamicists" staged their last-minute vote because they felt insufficiently represented on the special committee. Marginal scientists who love publicity (like a certain planetarium director I could name) have found the Pluto issue to be a real gravy train. Even Mike Brown, who is a real scientist of merit, knows he would look selfish if he argues to make himself a "planet discoverer". It's a win-win situation for him, because he is getting mounds of publicity now.

He doesn't sound happy about the situation (see http://www.gps.caltech.edu/~mbrown/whatsaplanet/requiem.html ) but I'm still unclear why he supported the eight-planets proposal at all.

I dunno ... because he thought that it made the most scientific sense?

Bill

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You really should read Mike Brown's paper "Planetesimals to Brown Dwarfs: What is a Planet?" http://www.gps.caltech.edu/~mbrown/papers/ps/basribrown.pdf

I'm apt to misrepresent things I don't fully understand, but with that caveat, the point is that the arrangement we see isn't by chance; it's an artifact of how planets form in the first place. Our accretion disk went into eight planets, each of which sucked up their local bits of it. In two places, the process stalled. The Asteroid Belt we can blame on Jupiter, which probably depleted too much of it to let Ceres become a planet. The Kuiper Belt was just too far out.

Since there cannot be a Saturn-sized planet 180-degrees away from Saturn in the same orbit, we don't have to worry about it being a planet or not. The arrangements are not arbitrary. You could conceivably have a double planet (as I suggested earlier, whenever the mass ratio is less than a factor of 25), but I don't think that changes things much.

The point is, there seem to be good, solid, scientific reasons to distinguish the eight bodies called planets from everything else in the solar system. It's a challenge to come up with the most general, best motivated definition that agrees with this, but after reading Mike's paper, it really does seem like that's the place we want to end up.

If those constituted "good, solid, scientific reasons to distinguish the eight bodies called planets from everything else in the solar system" you could equally make the same claim for distinguishing the four Galilean moons from the rest of the rubble orbiting Jupiter.

In fact to come right down to you could argue equally scientifically that the only "true" planets in the solar system are the four gas giants. Everything else is an oversized or undersized asteroid which was unable (for one reason or another--proximity to a gas giant, proximity to the Sun, etc) to suck up enough gas to make it into the true planet league of Jupiter, Saturn, Uranus, and Neptune. You have the little runts like Ceres and Pluto, the middling runts like Mercury and Mars, and the large runts like Venus and Earth. If one is going to argue that it makes no sense to include midgets like Ceres and Pluto among the planets it surely makes equally little sense to include Mercury and Earth in the same class of astronomical object as Jupiter, for compared to Jupiter and Saturn Earth is as much a midget as Pluto and Ceres.

As for the IAU's definition, had Resolution 5A made scientific sense why was there a need for footnote one? It implies the IAU was afraid the terms of that Resolution were not sufficiently clear enough to embrace all the favoured eight.

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Stephen

Does someone know if the IAU had a new list of dwarf planet candidates ?

Is Table 2 on
http://www.iau2006.org/mirror/www.iau.org/...au0601_Q_A.html
still the base for further consideration ?

On
http://en.wikipedia.org/wiki/Dwarf_planet
is another list. Is this list official ?

On that list Charon is a possible dwarf planet. Is IAU working on a definition for a "double dwarf planet" ?

If I conclude the discussion right I found three definitions for a double dwarf planet:
- mass ratio is less than a factor of 25 to have stable L4 and L5 points (Greg)
- barycenter is outside of the bodies (former IAU Resolution 5)
- tidally locked rotations (David)

Since definition 2 and 3 can change the classification with time I think a mass ratio definition with scientific background would be good. Therefore I support definition 1.

[quote name='JRehling' date='Aug 28 2006, 05:52 AM' post='65886']Uranus and Neptune are like each other physically. You could hardly ask for two worlds to be more similar. I'm sure Pluto is more different from a typical KBO than Uranus and Neptune are unlike each other.[/quote]

I was wondering if I should mention that. Uranus and Neptune resemble each other alot, true, but there's only two of them. Pluto, 2003 UB313, and 2005 FY9 clearly have much in common. Ceres is probably more unique in physical sense, but it is located in the asteroid belt.

[quote]And the "different distances" thing is a non-starter: If there were another Saturn orbiting the Sun in the same orbit, but 180-degrees away, who would deny that they are both planets? Or, for that matter, if something in the orbit of Halley's Comet were twice the size of Earth, would it not be a planet?[/quote]

Read "different distances" as "unique orbit" compared to other of its kind. This is circular reasoning, I admit that.

[quote]This is all science by it-is-because-I-say-so.[/quote]

That's the problem because "planet" is so much culturally defined. Dozens of planets (which would be scientifically more justificiable) just isn't acceptable.

[quote]The history is simple: There was once a clear gap, between Mercury and Ceres, in the sizes of Sun-orbiting objects. Even before KBO discoveries, the fact that natural satellites closed that gap should have been a clue. When the gap was closed by KBO's, the reason for the distinction went away too. Astronomers are now undertaking a very weird and illogical endeavor to jump through hoops to reinvent that gap in other terms. If the gap is gone, the gap is gone. Accept it. Reverse-engineering a category based on other properties is fruitless.[/quote]

I fully agree with that, if you are going to use "planet" as a scientific term. That's why the term "planet" should be phased out in astronomy. Instead we should have a term for a planetary mass object (like planemo), for example.

[quote]The tunnel vision here is tremendous. Not only is no one asking WHY the term needs a formal definition (except because-I-say-so), but no one is considering how the next gap-filler is going to blow this definition away. This is as bad as if someone had chosen to address the Y2K problem by using THREE digits to represent years. If we find something as big as Mercury orbiting more than 100 AU out in a roughly circular orbit, with nothing else close to its size known within 0.5 AU of it, this definition will be shredded. Then what?Put another bandage on the severed limb?[/quote]

It was the public who actually needed the definition, and now astronomers can freely say that Pluto isn't one of the planets. This was just a more elegant way to demote Pluto (instead of plain because-I-say-so).

[quote]"Planet" has no scientific justification. Thresholds and intricate definitions aren't, because science studies the objects in question, ipso facto scientific. This is art. Bad art.[/quote]

Right. "Planet", however, is an important term culturally and is still needed.

Stephen: It would certainly make a lot of sense to distinguish the four terrestrial planets (rocky planets?) from the four jovian ones (gas planets?) Again refering to the brown paper, it seems that something special has to happen to even get terrestrial planets rather than just getting a super-jovian in a 4-day orbit. Lumping these together is indeed a concession to the "cultural definition," but not a big one.

Note that "dinosaur" is also a broad term, popular with the public, but divided between the orders ornithischia and saurischia; there actually is no order "dinosauria." But have a look at the "taxonomic definition" here for an attempt at it: http://en.wikipedia.org/wiki/Dinosaur to see just how complex this can get. It doesn't seem to bother the public, just as long as they believe the "wise men" really do know what's a dinosaur and what's not.

This "controversy" doesn't seem to have lead to an attempt to drop the term "dinosaur," nor has it required any scientist to pretend that ornithischians are the same as saurischians.

Science can make minor concessions in order to improve communication with the public, and it doesn't have to sell its soul to do that. Public support really matters if we want them to keep funding unmanned space probes, so it's important to keep them believing scientists really know what they're talking about.

It still seems to me that the eight-planet solution is completely salvagable. The public will care little about the deep scientific debate that cleans up the definition -- just as long as the external effect is consistent. They cope with unpopular Supreme Court decisions the same way.

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