Talk:Dwarf planet/Archive 1

From Wikipedia, the free encyclopedia

This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page.

Contents 1 Dwarf Planets 2 BBC article on the so-called vote by the IAU 3 Extra possible dwarf planets 4 Size, context? 5 Is Charon a Dwarf planet? 6 Is Neptune a dwarf planet? 7 Shouldnt this be a category? 8 Table 9 "Clearing the neighbourhood of its orbit" 10 Welcome to the Dwarrowdelf 11 List of possible dwarf planets 12 The sun or a star 13 The bulleted list above the TOC 14 "Not a satellite" 15 Isn't "mesoplanet" a much preferable term? 16 Mistake? 17 PSR B1257+12 D 18 mergefrom ice dwarf 18.1 Discussion 18.2 Votes 18.3 Consensus Conclusion 19 Change category to region 20 The Picture 21 Merge Table of dwarf planets in the solar system 21.1 Support 21.2 Oppose 21.3 Neutral 21.4 Comments 22 Image 23 Hyphenation 24 English Only?

Dwarf Planets

Someone started a Dwarf Planets article, too. I will merge it here. The encyclopedic article should be in the singular.Derek Balsam 19:21, 11 August 2006 (UTC)

BBC article on the so-called vote by the IAU

http://news.bbc.co.uk/2/hi/science/nature/5283956.stm In light of this, I call for a "stop work" on the subject of so-called Dwarf Planets and a revert of all Planet articles back to before this vote was taken. It is very clear that they waited, at least in my opinion, till only a majority of Pro-Dwarf Astronomers were left before they took their vote. 424 is not a majority. Read the BBC article and you will understand what I mean. Here is a quote from the article, its very enlightening [quote]Alan Stern agreed: "I was not allowed to vote because I was not in a room in Prague on Thursday 24th. Of 10,000 astronomers, 4% were in that room - you can't even claim consensus.[/quote] Opinion by Magnum SerpentineMagnumSerpentine 8-28-06

They are just a few unhappy astronomers, they werent they, so they forfeit their right to vote. Until even mentions the possibility of a decision reversal, then no stop work is needed -- Nbound 12:49, 28 August 2006 (UTC)

Oh I see.... since there were only 424 members present for the vote, that makes the other 9500+ unhappy Astronomers eh? come next meeting, I suspect those who engineered this so-called Vote will be in for quite an awakening. User:Magnum Serpentine 8-28-06

Bah, they knew the rules. They chose not to participate. They're mad because they don't understand the basis for the decision. Once they start reading the papers that have been written over the past decade and a half, they'll change their minds. So far, Stern's the only one who's spoken up and I'm told his statements on the subject of clearing the neighborhood have contradicted things he's published in the past. My guess is that he expects the "demotion" to effect his funding for the Pluto mission and he thinks he can keep interest in it by generating publicity. It's probably a wise decision in his situation. --Aelffin 18:38, 28 August 2006 (UTC)

And what of those who had to leave and were calling for a vote before the last day? I believe if they knew the vote was coming they would had at least arranged to put off the vote. However, since they did not put off the vote, and they left, that leads one to suspect that they were either misled to believe the vote was put off or it was not going to happen... In any case It looks very much like the whole thing was engineered. We shall see next time this disrespectable organization comes together Magnum Serpentine

Well, I knew about the vote several weeks in advance and I'm just a lowly textbook editor. Anyway, the vote was something like 150 to 250, so where are these hundred astronomers who cared so much and yet were too busy to schedule their trip accordingly? The fact is most astronomers don't work in planetary science, so they don't care that much. More importantly, it was the IAU that wanted to keep Pluto a planet, so your complaint should be directed at the world's astronomers, not the IAU. It was the astronomers who re-wrote the proposal so it would fit what they've been saying for years. And it makes sense. Pluto never belonged with the planets; read any high school science textbook and you'll understand why. --Aelffin 00:43, 2 September 2006 (UTC)

• Good article, the division between Planets and Dwarf planets is very questionable. By that criteria Earth and even Jupiter are dwarf planets O.O and obviously Neptune. None of these planets had cleared their neighbourhood. Besides, the fact one has neighbours does not mean you are not a person. I just discovered I'm a dwarf human, because I've neighbours. LOL. Really lame and precipitated decision, which will only blur things. That was not a scientific definition but a witch hunt. --Pedro 19:18, 28 August 2006 (UTC)

The difference between the planets and dwarf planets by planetary discriminant (ie. their mass compared to the mass of all other objects in their path) is several order of magnitude different than the dwarf planets, techinically Ceres has actually cleared its area the most out of the dwarf planets, and it pales in comparison with even the worst of the main planets

Extra possible dwarf planets

According to space.com, there could be up to 53 dwarf planets according to the new definition [1] and the asteroids that were mentioned in the article are also mentioned by New Scientist here: [2]. However, the phrase "The list of dwarf planets which are also plutons could also be vastly extended with round or near-round solar system bodies like Quaoar, Orcus, 2005 FY9, and others." needs a citation, and the term "near round" properly defined. AFAIK, Ceres is barely round enough to recieve planetary status. However, I recall reading in another article that any planet less than 500miles across would not be spherical enough to be a planet, hence the official word of only 12 planets. I can't find the article now but I'll keep looking. Eccentricned 14:23, 16 August 2006 (UTC)

The three "round" asteroids and the KBOs listed are included in many pages which carry the news as "runner up" candidates, including the BBC. -- Jordi·✆ 14:31, 16 August 2006 (UTC)

Size, context?

Could someone explain the context to the size? It's probably explained on other pages, but as stated on this page, it might strike the reader as an arbitrary cut-off (whereas the roundness criteria was at least based on objective physical properties). Pluto is very different in composition from the four planets that come before it... is the Mercury cutoff an approximate guess at where that transition might occur in other solar systems? Or is it simply a conservative definition that makes the smallest possible change to textbooks? --Interiot 14:33, 24 August 2006 (UTC)

There is a mathematical yardstick that says the farther out you are and the slower you move -- the bigger you need to be as a planet to clear all the space junk from your orbital path. Oh let's not forget the bigger you are the bigger the orbital zone you are expected to clear. However that is just selected theoretical club for changing the definition of a planet.

I am sure the actual reasons for the change are many to include: actual naming credit (fame and the selling of names in the catalog - just like comets), changing definitions to help planet formation theories (i.e. dwarf planets be a different category of data we can mostly ignore), easier classification for purposes of life on other planets and space colonization (clear zone means vastly lower catastrophic collision rate).

Frankly it is clear that faster orbits and bigger planets have advantages during planetary accretion in clearing orbits closer to the stars -- but that is not a sign of different mechanics than "dwarf planets" nor is it the only definition of stable enough for life. The very reasons Pluto hasn't cleared its orbit means that collisions are rare in terms of life and colonization -- most everything in a wide orbital range is still moving more or less synchronously with Pluto for millions of years.

Is Charon a Dwarf planet?

CalRis: I think that the statement that Charon is excluded from the group of dwarf planets is not correct. The definition of 'dwarf planet' rests on four conditions, the first three of which Charon clearly fulfills. The fourth one, i.e. "not being a satellite", is less clear. But as the barycentre of the Pluto/Charon-system is outside of the primary, I believe that Charon IS a dwarf-planet or at least is not yet assigned to any group (either dwarf-planet or small solar system object). Actually this barycentre-condition was included in the draft resolution. Its removal didn't exactly make things clearer for Charon, but Charon's status is definitely not clear, yet. I'm looking forward to hearing your opinion. CalRis.

Agree with your comments. They left out the details. Personal gut feeling? Charon is a satellite and Pluto/Charon is a binary. The article will be edited by hundreds editors or so in the next hour so I’ll leave them the job. Eurocommuter 14:51, 24 August 2006 (UTC)

I belive Charon is included as on of the inargural four dwarf planets. Most sources are reporting Charon as a dwarf planet, with it and Pluto being a binary planet. Should it be classified as a Plutino instead of a moon?

Read this:

http://www.iau2006.org/mirror/www.iau.org/iau0603/index.html

This means that the Solar System consists of eight "planets" Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. A new distinct class of objects called "dwarf planets" was also decided. It was agreed that "planets" and "dwarf planets" are two distinct classes of objects. The first members of the "dwarf planet" category are Ceres, Pluto and 2003 UB313 (temporary name). More "dwarf planets" are expected to be announced by the IAU in the coming months and years.

Hence, Charon is not (yet) a dwarf planet. -- ran (talk) 00:16, 25 August 2006 (UTC)

• no, it was excluded, and that had strong opposition. We know enough of Charon to classify it as a dwarf planet, but it does not fullfil the criteria, and it is a satellite of a dwarf planet, Pluto this one is a Dwarf because it wounders in the Kuiper Belt.--Pedro 11:05, 25 August 2006 (UTC)

Is Neptune a dwarf planet?

Since Neptune has failed to clear the neighborhood in it's orbit of Pluto, by the stated defintion it is also a dwarf planet. They need to refine the definition a bit more.

• • CalRis: Your concern was raised at the general assembly of the IAU but negated by those responsible. My interpretation/explanation: Neptune DID clear its neighbourhood (partially during its accretion phase, but also later when it - probably - migrated radially outward, at that time probably by resonance sweeping). The result: objects remaining after Neptune's creation in its neighbourhood were either ejected out of the solar system, moved further inside or outside. Some, Pluto most probably one of them, were trapped (by "resonance-trapping") inside so-called mean-motion resonances (in the case of Pluto in the 3:2-resonance). What further proof of Neptune's ability to "clear" (other drafts of the resolution preferred the word "dominate") its neighbourhood is needed?

Thanks for this explanation. Perhaps the article needs to explain what is meant by clearing it's neighborhood. A question from a non-expert: Could a resonance-trapped object ever be considered a planet? Or does this essentially become a type of satellite? –RHolton≡– 16:05, 24 August 2006 (UTC)

I agree that a definition is required, and I don't have one. As is explained in the Pluto article, Pluto and Neptune don't actually "share" an orbit anyway, so I do not understand why the "cross" with Neptune means that Pluto has not cleared the neighborhood of its orbit. I also agree that if Pluto has not "cleared the neighborhood," it is difficult to see how Neptune has. When I first heard about this neighborhood thing, I thought they were going to say that Pluto fails the test because other objects in the Kuiper belt infringe on its orbit, which would make sense. But saying that it fails because of its relationship with Neptune does not make sense, or at least I have not yet heard a satisfactory explanation. I also am wondering about the wisdom of the designation "dwarf planet," when none of the stated criteria have to do with size. What are they going to do if (when?) they find a Kuiper belt (or other trans-Neptunian) object that has not "cleared its neighborhood" but is larger than Mercury? Then they would have a "dwarf planet" that is larger than one of the classical planets. It is unlikely that such an object exists, but then again, when I first learned about the planets (in the early 60's), there was no moon of Pluto, most of the moons of the gas giants were unknown, Saturn was the only ringed planet, and the Kuiper belt was an unsubstantiated theory. Even two years ago, no Kuiper belt object larger than Pluto had been discovered, and now one has. Who is to say that there definitely isn't one larger than Mercury? 6SJ7 18:00, 24 August 2006 (UTC)

Well, the Clearing the neighborhood article has been started, and it has a tag on it saying that an expert's help is needed. And it is, but the article is a start. It turns out, anyway, that Neptune has nothing to do with any of this. Pluto has not cleared the neighborhood of its orbit because other Kuiper belt objects infringe on its orbit, and if it was a real planet it would have been big enough to absorb those objects as it was forming, or at least capture them as satellites. Or at least that is what the IAU appears to be saying, and it seems logical. Neptune and Pluto do not share an orbit, Pluto just happens to get closer to the Sun than Neptune does at times. 6SJ7 01:39, 25 August 2006 (UTC)

Being grammatical - "it's" = it is.

Shouldnt this be a category?

I think we should turn this article into a category. Discuss. —The preceding unsigned comment was added by 129.42.208.182 (talk • contribs) .

• Suggestions offered with no supporting reasoning are unlikely to be taken very seriously. Also, please sign your posts on talk pages by typing four tildas: ~~~~. Responding to your suggestion, I'd say that there could be a category:Dwarf planets, but this page should exist with or without the category. –RHolton≡– 15:54, 24 August 2006 (UTC)

There should be a category, but it clearly shouldn't replace the article. I will make one. Joe Llywelyn Griffith Blakesley _{talk contrib} 11:50, 1 September 2006 (UTC)

Category:Dwarf planets exists. 132.205.44.134 04:08, 4 September 2006 (UTC)

Table

Please, a nicer table....--TheFEARgod 17:33, 24 August 2006 (UTC)

Go ahead.Derek Balsam 17:37, 24 August 2006 (UTC)

Erm, not quite sure what do do about it, but the current measurement for Ceres doesn't quite fit in a diameter catagory... Maybe list it as "at poles" and "around"?... -Tiak 05:49, 25 August 2006 (UTC)

"Clearing the neighbourhood of its orbit"

What does "cleared the neighbourhood around its orbit" mean? --Fang Aili ^talk 17:47, 24 August 2006 (UTC)

Second. I have no idea what this means.. someone please explain! --Djedi 20:17, 24 August 2006 (UTC)

There are objects sharing the orbits of the eight planets, the Trojan asteroids of Jupiter, Cruthine in Earth's orbit. But they survive only because they have a stable resonance with the major body. By the same token, Pluto is in a 3 to 2 resonance with Neptune, as are some other bodies out there. Whereas the Kupier Belt objects seem to coexist without having much effect on each other. That, I'd assume, is the point. --GwydionM 20:28, 24 August 2006 (UTC)

"This definition demotes Pluto from a planet to a dwarf planet because it has not cleared the neighborhood of its orbit (the Kuiper Belt)." Can someone clarify this sentence? In what sense is the word "clear" being used here? It would also be helpful to say what an "orbit neighborhood" is, at least until someone writes that article. Recury 20:47, 24 August 2006 (UTC)

As I understand it, when planets pass through their orbit they essentially "pull" asteroids and other small bodies in and thus remove them from the orbit. That's what is meant by "clearing" the orbit. Pluto, on the other hand, is too small and its orbit too large; its orbit is not clear of asteroids and other small celestial objects. -4.153.225.232 20:52, 24 August 2006 (UTC)

That makes sense. Orbit neighborhood is pretty selfexplanatory then, I thought it might be a technical term or something. Recury 20:55, 24 August 2006 (UTC)

The size of the orbit doesn't matter. However, in Pluto's case the eccentricity and obliquity of its orbit do matter. I don't know (nor do I feel like doing the math) if the obliquity of Pluto's orbit will ever bring it close enough to Neptune for the issue to really matter, though. (obviously, if Pluto did come close enough it would be cleared, probably not by accretion, but probably by being captured, or by being flung out into space). •Jim62sch• 23:50, 24 August 2006 (UTC)

The following language that has been inserted implies that Stern and Levinson endorse the use of the "neighborhood clearing" criterion for defining planets: "Astronomer Alan Stern, Levison, Steven Soter and others have argued for a distinction between dwarf planets and the other eight planets based on their inability to "clear the neighborhood around their orbits" [...] Stern and Levison found a gap of five orders of magnitude in Λ between the smallest terrestrial planets and the largest asteroids and KBOs." I don't know what Levinson's take on the matter is, but Stern has been very critical of the current 'definition of a planet' scheme. Soter may be using Stern's formula as a planet-defining scheme (and certain members of the IAU may be using Soter's criteria as the basis for IAU regulations) but that doesn't make Stern someone arguing "for a distinction between dwarf planets and the other eight". In fact Stern supported and supports a definition of planet based solely on hydrostatic equilibrium, similar to that of the original draft proposal to the IAU. --RandomCritic 07:47, 31 August 2006 (UTC)

Welcome to the Dwarrowdelf

With all of the potential dwarf planets out there, the Kupier Belt is now a Dwarrowdelf, a dwelling-place of dwarves. The word is real, used by J. R. R. Tolkien

--GwydionM 20:24, 24 August 2006 (UTC)

Actually, I believe the -delf in Dwarrowdelf is supposed to reflect the word delve, so perhaps "digging-place of dwarves" is more accurate. It would be nice though if astronomers were inspired by the new term to start naming Kuiper Belt Objects after Tolkienian dwarves or dwarfs of mythology (Thorin, Ori, Bombur...:-). Thylacoleo 03:17, 25 August 2006 (UTC)

List of possible dwarf planets

I think the list on Mike Brown's website plus discussion of the asteriods listed as candidates in the earlier definition (Vesta, Pallas, and Hygiea) might be the best approach to the candidate section of this page. Right now it seems thrown together as people find wikipedia articles that list diameters that they think might fit. --Aranae 20:27, 24 August 2006 (UTC)

(19308) 1996 TO66 was just removed from the list of possible dwarf planets. It's one of the 45 on Brown's informal list but is certainly less well understood than many other objects and there are probably larger objects not included. Again, what are the criteria we're using to determine inclusion into this list? The edits seem like a mix of random opinions. --Aranae 05:19, 25 August 2006 (UTC)

As there is, as yet, no official lower bound; as none even of the larger candidates has yet been accepted as a dwarf planet; and as a very long list of objects with very uncertain sizes would be confusing, I think it's best to confine the list to the few largest candidates. Most of these are listed at Trans-Neptunian object#Largest discoveries. Drawing an arbitrary line at c. 750 km happens to exclude any object which doesn't currently have a wiki.RandomCritic 05:24, 25 August 2006 (UTC)

Red links should never determine these things. It looks like 400-500 km might turn out to be the cutoff for roundness for ice composition and 800-900 km for rocky composition. I've seen 800 km bounced around a lot and I think would represent the conservative estimate. 600 is another figure that is used in news articles. For mass, 5x10^20 is being cited in news articles. 750 seems very arbitrary and just seems like a number pulled out of a hat that fits in the ranges. Personally, I think we should use the "candidate 12" plus Charon and minus Vesta, Pallas, and Hygiea, but discuss those. Those are really the only remotely official dwarf planet candidates listed anywhere. I don't see that we can justify 2002 UX25 and 2002 TC302 which were excluded from the IAU's list presumably due to uncertainty about their sizes and not include objects like 2003 AZ84, 2005 RN43, 2003 MW12, 1996 TO66, or even Chaos. Those error bars are quite large and the small differences in estimates become somewhat meaningless at that point. I wouldn't be opposed to a list of candidates and a separate list of objects which may turn out to be dwarf planets but for which much more information is needed. That may be too crystal-ballish for wikipedia, though. --Aranae 06:15, 25 August 2006 (UTC)

750 is a number that is pulled out of the hat, but given the uncertainties it's no better or worse than 600 or 800. It just also happens to be a dividing line at which the Brown list you point to, and the very different figures used on Wikipedia, happen to nearly agree. The "candidate 12" press release image you link to just appears to a haphazard guess as to what bodies fit the IAU definition. There is apparently no access to the IAU's supposed "planet watchlist", and I'm not at all sure that such a document exists other than in hypothetical terms. Anyway, if you want to delete UX25 and TC302 be my guest; but you may have to argue it out with the people who added those candidates. :) RandomCritic 12:22, 25 August 2006 (UTC)

The whole section is unofficial and unpublished. The key is that the objects in the image I linked to represent the unofficial speculation of an official committee charged with making a proposal. Brown's website represents his unofficial speculation, but it's the unofficial speculation of one of the top researchers in the field. Right now, our list is the unofficial speculation of the wikipedia community. I think the first two choices are much more appropriate. I am just one of the many nonexperts attracted to these pages by the recent press. I'd rather see this call made by a few of you more regular types. --Aranae 20:18, 25 August 2006 (UTC)

Well, all objects that orbit the sun that are biger then 1 Ceres should be included though it looks like all, if not, most are.Omega13a 08:31, 27 September 2006 (UTC)

The sun or a star

The new definition for dwarf planets only addresses objects around our sun. If you use the generic star then any larger than Mercury extrasolar objects are immediately classified as dwarf planets but this was not addressed in the new definition. I think it should say the sun and not a star which matches the wording of the new definition. --Daniel Schibuk 20:31, 24 August 2006 (UTC)

I suspect you meant to say either "smaller than Mercury" instead of "larger than Mercury" or "planet" instead of "dwarf planet". --Aranae 20:39, 24 August 2006 (UTC)

I totally meant what I wrote but it seems that everybody is on the same page with a dwarf planet orbiting the sun. I was just saying if you use just the generic star we may not know the neighborhood of an extrasolar object. This therefore means an object larger than Mercury that may not have cleared its neighborhood would be considered a dwarf planet. It would really strange to call that object a dwarf planet when it is a very large object and possibly bigger than the Earth. -- Daniel Schibuk 11:45, 25 August 2006 (UTC)

Yes, this is exactly the problem with the IAU definition. Hopefully it will be refined at their next convention. Many planetary scientists are refusing to acknowledge the current IAU definition as it is heliocentric in its specific mention of the Sun, and the language is intrinsically self-contradictory and thus useless. I write software (six years on NASA research funding so far), and I consider this an example of namespace polution. My parser would throw a fit if I tried to pass it a piece of code so poorly written. I'm just sticking to calling all bodies large enough to be round by their own gravity yet smaller than brown dwarfs, planets. If they happen to be in close orbit with another planet such that their barycenter is beneath the surface (where is Jupiter's surface again?), then I'll call it a moon, even though it is still also a planet. They really jumped the gun on this one, but hopefully the controversy sparked will force a better understanding of physical reality. Seriously, should an electron be called a 'dwarf electron' if it hasn't 'cleared it's neighborhood'?! Fisherted1 19:55, 15 September 2006 (UTC)

The bulleted list above the TOC

Please reword the first and fourth of these so that they do not appear to contradict each other. Georgia guy 20:36, 24 August 2006 (UTC)

Just realized that this is the same complaint that I had, just not quite as descriptive. :P -4.153.225.232 20:46, 24 August 2006 (UTC)

"Not a satellite"

What does the new classification mean by stating that an object must be "in orbit around a star but ... not itself a star," and must not be "a satellite"?

If it's an object in orbit around a star, it is a satellite of that star. Is it referring to man-made satellites? -4.153.225.232 20:45, 24 August 2006 (UTC)

• No, it is refering to celestial bodies such as Titan (moon), and our moon. -Pedro 21:12, 24 August 2006 (UTC)

• It means it can't be a satellite of anything other than a star. If it's a satellite of a planet or dwarf planet, then it cannot itself be a dwarf planet. 71.203.209.0 17:27, 25 August 2006 (UTC)

Isn't "mesoplanet" a much preferable term?

The phase "dwarf planet", coined for bodies like Pluto after the discovery of other Kuiper belt objects, is really rather misleading when one considers the many small, rocky bodies that orbit the Sun. "Dwarf planet" suggests a tiny body orbitting a large star.

Also, Ceres and Vesta have orbital characteristics much more akin to the eight "classical" planets than does Pluto: indeed they have lower eccentricities than Mars and very low inclination. Thus, it is misleading to classify a body like Ceres in the same group as Pluto and other Kuiper belt objects. (Interestingly Pallas and the small "Pallas family" have quite Kuiper-belt like orbits in terms of eccentricity and inclination, but most large asteroids do not).

"Mesoplanet" by comparison really is a much better fit for bodies like Pluto. Although smaller than many moons, it is much larger than most asteroids - indeed its moon Charon is larger than Ceres. And at least some Kuiper belt objects are still larger even if they are not nearly as large as Mercury or even the biggest moons of the gas giants. "Mesoplanet", as I emphasised above, indicates intermdiate size - between true "planets" and the thousands of tiny asteroids. It seems a much more proper term if bodies like Pluto cannot be called planets.

Do you agree?

Julien Peter Benney (luokehao)

You might have a case, but we really can't determine the proper definition, we can only report on what a scientific body has done. The one problem with asteroids like Ceres and Vesta is that they are "shepherded" by Jupiter, and to an extent Mars. •Jim62sch• 23:54, 24 August 2006 (UTC)

I prefer Asimov to the IAU, but what we have is what we have. Arch O. La ^{Grigory Deepdelver} 23:33, 28 August 2006 (UTC)

Actually we are supposed to report all viewpoints (WP:NPOV), so, if there is a verifiable source saying that people are using mesoplanet to describe dwarf planets, we should include that as an alternate term. The IAU are not omniscient.

Joe Llywelyn Griffith Blakesley _{talk contrib} 11:58, 1 September 2006 (UTC)

As far as I know, it's just fans of Isaac Asimov. But, is there something I don't know?Arch O. La ^{Grigory Deepdelver} 02:33, 5 September 2006 (UTC)

There is another reason that, in my view, "dwarf planet" is a bad choice of name. Generally, in English (and, I would guess, in any language that has nouns and adjectives), if you attach the adjective B to the noun A, the result is still an example of A. So, for instance, a toy poodle is still a poodle. (This does not, of course, apply when they are merged into a single word - e.g. a greenhouse is not a house.) However, the new IAU definition says that a dwarf planet is not a planet. Maybe the IAU could end the controversy, which I suspect is not going to go away in the near future, by rescinding just a little bit and allowing a dwarf planet still to be a planet as well. (I know there are existing violations of this rule - a Bombay duck {Mumbai duck??} is not a duck, Scotch woodcock is not a woodcock - but it would surely be better to avoid introducing new ones.) Jon Rob 09:14, 5 September 2006 (UTC)

Yes Dwarf Planet seems a poor choice of terms by the IAU because minimum planetary mass varies with orbital distance (and solar mass too). Thus we could potentially find distant dwarf planets in our own system bigger than the Earth. At sufficient distance around a massive star a Jupiter mass would be a dwarf planet. Perhaps the IAU will rethink the actual term used with this a recent change.

As far as the actual change, the most useful aspect of the new IAU definition is to clarify orbital domainance and to state that planetiod formation in that orbital zone is essentially over. This almost sounds like more of an orbital zone characteristic than a characteristic of the orbital body itself. I guess there is significance for finding life or colonizing in the awefully far future. But I am not entirely sure that non-dominant "dwarf planets" would always tbe subject to that frequent of collision. The deceptive thing about much longer period orbits with some junk still in the zone is that it takes forever for object to interact. Thus Pluto probably sufferes less frequent major events than the Earth. Stability is stability regardless of how clean the zone.

Mistake?

is not a satellite of a planet, dwarf planet, or other nonstellar body.

This doesn't seem to make sense. A dwarf planet can not be a dwarf planet?--Jersey Devil 00:02, 25 August 2006 (UTC)

I think I see now, it can't be the "satellite of a dwarf planet". My mistake.--Jersey Devil 00:15, 25 August 2006 (UTC)

PSR B1257+12 D

Should we apply the term dwarf planet to extrasolar bodies? PSR B1257+12 D, if it falls in the upper part of its estimated size and mass range would fit into dwarf planets probably. 132.205.93.19 02:40, 25 August 2006 (UTC)

No because the new definition as voted on by the IAU explicitly states that a dwarf planet must be in orbit around the sun. There is no mention of extrasolar bodies in new definition so this term should not apply to extrasolar objects. See "The sun or a star" section of this page for justification. --Daniel Schibuk 12:58, 25 August 2006 (UTC)

To what extent is it possible to identify extrasolar dwarf planets yet?

No doubt when "a sufficiency" of these bodies is discovered, the term used will be "Star X's dwarf planets"/terrestial planets/gas giants/Kuiper belt objects and Oort cloud.

Exactly. I really think we need a template:universalise tag (cf. template:globalise) stating "This article may not conform to an extra-solar view" on some of these articles.

If there are any similar extra-solar objects, they will inevitably be being called dwarf planets (regardless of what the IAU says; see my comment above about NPOV) and should therefore be mentioned.

If there are currently no such objects that makes it a little more difficult. However, given we have plenty of articles on whole designations for which no known objects exist, it would seem we should logically mention (if we have sources) what sorts of extra-solar objects discovered in the future the general public and the IAU would likely count as extra-solar dwarf planets.

Joe Llywelyn Griffith Blakesley _{talk contrib} 12:11, 1 September 2006 (UTC)

mergefrom ice dwarf

Change category to region

Dwarf planets are dwarf because they did not cleared the region (neighbourhood) they live in that means, that instead of:

Name Category

Pluto Plutino

UB313 Scattered disc object

Ceres Asteroid

it should be

Name Region of the Solar System

Pluto Kuiper Belt

UB313 Scattered disc

Ceres Asteroid Belt

--Pedro 11:23, 25 August 2006 (UTC)

PedroPVZ, there is no basis in either of the IAU resolutions for your claim that Ceres is "no longer an asteroid". Why did you put an "original research" deprecating flag on this article?RandomCritic 13:42, 25 August 2006 (UTC)

'Category' is fine. The objects are indeed members of each of those categories, whatever else they may also be. Pluto is a plutino. UB313 is an SDO. Ceres is an asteroid. They are also dwarf planets. Kind of like this: Jupiter is a planet. It is also a gas giant. UB313 is an SDO. It is also a TNO. Things can belong to more than one category.Derek Balsam 13:44, 25 August 2006 (UTC)

• Watchlist is not the same as the IAU watchlist that includes 12 bodies (including 3 asteroids)

The "IAU watchlist" is not a verifiable source, as it has never been published. It is doubtful whether an artist's interpretation qualifies as a source. In any case the Possible Dwarf Planets table is just that -- a table of objects that might, given the criteria, be classified as dwarf planets. It is not an attempt to replicate an unpublished IAU document.RandomCritic 14:13, 25 August 2006 (UTC)

• The first diagram is original reasearch. It puts Ceres in the border between Small body and Dwarf planet. Ceres is clearly a Dwarf planet.

The diagram is wrong. The words "original research" and "wrong" do not mean the same thing, however.RandomCritic 13:59, 25 August 2006 (UTC)

I'll see if the original artist is willing to change the diagram and will suspend the diagrams out of the visible text for the time being.RandomCritic 14:32, 25 August 2006 (UTC)

• AFAIK "category" is not a proper division of Dwarf planets.
• text in Possible Dwarf planets is not science, but fantasy or Original research at best. semi-spherical?!?!

The text was poorly worded, but was hardly fantasy, and could easily be reworded.RandomCritic 14:10, 25 August 2006 (UTC)

• "Small Solar-System Bodies" is for asteroids, comets, centaurs, transneptunians, etc. The name for the group of Pluto and UB313 will be created. That was very clear. --Pedro 13:47, 25 August 2006 (UTC)

That the category Small solar system bodies includes asteroids does not imply that all asteroids are small solar system bodies. In fact, the IAU definition of SSSBs precisely states that it includes "most of the Solar System asteroids" and "most Trans-Neptunian objects", which very clearly indicates that there is some small number of asteroids and TNOs that are not SSSBs. RandomCritic 13:59, 25 August 2006 (UTC)

I'm going to remove the flag as I think that all the substantive objections have been addressed. It seems to me that the other objections are matters of idiosyncratic interpretation and opinion, and that the article is being criticized not for original research, but for failing to be POV. RandomCritic 14:20, 25 August 2006 (UTC)

yes, most because Ceres was an asteroid now a Dwarf planet. And there are 3 other asteroid that can be reclassified as Dwarf planets.--Pedro 14:41, 25 August 2006 (UTC)

No. The term asteroid was not deprecated by the IAU, and was not the subject of their vote. Asteroids still exist. You need to try to understand that objects can easily belong to more than one category. Pluto is a dwarf planet. It is also a Kuiper belt object. It is also a plutino. Ceres is a dwarf planet. It is also a main belt asteroid. What is so hard about that concept?Derek Balsam 14:50, 25 August 2006 (UTC)

• bah. Yes, asteroids still exist, but Ceres isn't one any longer. I know people in wikipedia like the "plutinos" and the "cubewanos" a lot, but that's not a reason. Kuiper belt and Asteroid belt (their locations) are enough, and not ambigious like that categorization, that is most probably biased. -Pedro 15:44, 25 August 2006 (UTC)

Provide an official statement from the IAU that says, precisely, "Ceres is not an asteroid" or "Ceres is no longer an asteroid" and I'm sure everyone will be happy to change the article. RandomCritic 16:55, 25 August 2006 (UTC)

És teimoso. You know there's no such statement. But there is no statement that says "Ceres is an asteroid", but there is the strong "Ceres is a dwarf planet", besides "asteroids" were never an official category, asteroids were "minor planets", now "small bodies of the SS". Asteroids have no media attention like Planets. Noone cares if the asteroids loose a member.

• if you want a "drawing":
• popular -> official
• moon -> satellite
• asteroid -> minor planet

after the definition:

• small planet + bigger minor planets -> dwarf planets
• remaining minor planets -> small bodies of the SS.

That's enough. I think the IAU does't write for children. They just said Pluto, and Ceres are dwarf planets, ditto: pluto is not a planet, Ceres is not a minor planet. --Pedro 17:06, 25 August 2006 (UTC)

The Picture

Is it possible to get a new picture of Pluto, maybe an artists conception? The current one looks like a disco ball. --Pahoran513 00:34, 26 August 2006 (UTC)

How about this one? --Exodio 03:26, 26 August 2006 (UTC)

I think the caption needs to be changed. It isn't clear which is supposed to be Pluto... why are there two? What is the other? --Kimbalee1 05:27, 26 August 2006 (UTC)

Charon, maybe? Arch O. La ^{Grigory Deepdelver} 10:38, 26 August 2006 (UTC)

Which is Charon and which is Pluto? The caption still lacks that information. -24.92.41.95 02:46, 8 September 2006 (UTC)

Pluto is the larger one -- Nbound 02:49, 8 September 2006 (UTC)

Merge Table of dwarf planets in the solar system

Support

1. Support. I don't see why this needs to be a separate article; any necessary information in it should be incorporated into the tables in the present article. RandomCritic 22:56, 26 August 2006 (UTC)
2. Support as per RandomCritic. Arch O. La ^{Grigory Deepdelver} 23:12, 26 August 2006 (UTC)
3. Support The info should be here. I suspect there will be a lot of these in the future but we can deal with that then. Sophia 08:11, 27 August 2006 (UTC)
4. Support The table should be part of this article, not a seperate article. Md84419 10:20, 27 August 2006 (UTC)
5. Support As above and see comments below. C-squared 01:54, 29 August 2006 (UTC)
6. Support Shoot, I messed up and didn't check for the comments. I redirected the table to the dwarf planet article as it originally was. Oops ... should I revert? *blush* -Seinfreak37 19:12, 29 August 2006 (UTC)

I went back and incorporated all new information from that table into the one in this article. RandomCritic 02:16, 30 August 2006 (UTC)

1. Support For three entries this shouldn't be a seperate page. Even with double the entries it should be part of this page. Perhaps when (if) the number ever reaches an unmanageable size the page can be remade, but for now it's superfluous. aLii 16:26, 16 September 2006 (UTC)

Oppose

1. Oppose Most important Wikipedia articles are either already too long or on their way to getting there. As most of us know, excessive article length contributes to slow loading and other technical problems. Leave as is with emphasis on link to table. Rlquall 14:33, 27 August 2006 (UTC)

2. Oppose We are in process of discovering exoplanets and broadly speaking, exo-objects around other star systems. Sooner or later, more likely sooner, we will discover "exo-dwarf planets" along already discovered "exoplanets". Lets leave separate page for Solar system dwarf planets and for general definition of all dwarf planets, including those in Solar system and in other star systems. We will need also "exo-dwarf planet" page one day. Homo Cosmosicus 15:45, 27 August 2006 (UTC)

Its not fair to mix "Planets" and "dwarf planets" into one table and to call it "table of dwarf planets" and then as such merge it with the article Dwarf Planets. Page Table_of_dwarf_planets_in_the_solar_system should contain only the list of dwarf planets, instead now after voting there are mixed "Planets" and "Dwarf planets" together. I fixed that error. Please learn to live with the fact that the "dwarf planets" are not "Planets". Homo Cosmosicus 13:42, 16 September 2006 (UTC)

3. Oppose Pluto was demoted because cutting edge research suggests we may be finding tens or hundreds of "dwarf planets" in the coming years. While there may only be three right now, it's just a matter of time before there's thirty. Let the page be, if it was merged back here it would end up getting its own page in a year or two anyhow... save someone else the time. ;P Utopianheaven 09:14, 28 August 2006 (UTC)

Comment, ever heard of the policy that Wikipedia is not a crystal ball? aLii 17:25, 17 September 2006 (UTC)

Neutral

Comments

Re: "Oppose" #2: Leaving aside the technical inability of current planet detection methods to detect ordinary terrestrial-sized planets, let alone "dwarf planets", the term "dwarf planet" has been defined by the IAU for the Solar system -- for extrasolar systems nothing has been defined at all. RandomCritic 16:47, 27 August 2006 (UTC)

The opposing arguments say that the table's length will eventually be a problem, and while that might be true, I think it's a preemptive strike against what's currently a non-problem. The table itself is not strong enough to stand alone as an article in its current form. Wikipedia is an organic, evolving beast, and common sense says right now that the table should be merged in here. Let's cross that bridge when we get there. C-squared 01:59, 29 August 2006 (UTC)

I echo C-squared's thinking/ The article is currently not too long, and this information may not be enought to stand as its own article, except as a stub. In the meanwhile the information should remaine here .As we discover other exo-objects that fit witin the other article, it can be expanded, so I'm not opposed to a separate article for Solar system dwarf planets including those in other star systems but this information should be kept here and can be changed later as the other page fills up per new discoveries, and/or if this page becomese too large.Giovanni33 02:52, 2 September 2006 (UTC)

Now I see the original table was changed from just table of dwarf planets to the "Table of planets and dwarf planets in the solar system", this is attempt to represent planets and dwarf planets as somehow almost equal, while there is clear distinction between those two objects.Homo Cosmosicus 13:14, 16 September 2006 (UTC)

Image

Hi, can we have an image of the three dwarf planets? Like the terrestrial planets one. I tried, using Image:Three proposed planets.jpg and Image:Plutoncharon.jpg, but failed miserably. Friggin' paint... I think this would improve the article's quality greatly - Jack (talk) 23:15, 28 August 2006 (UTC)

Hyphenation

According to the fifth paragraph of this site <http://skytonight.com/news/home/3707031.html> , the term dwarf planet should be hyphenated (ie) dwarf-planet, not dwarf planet. What is the now official designation ? However, whatever it is, I would expect most people to look for this term unhyphenated. The Yeti 11:00, 29 August 2006 (UTC)

The IAU refers to the classifications without the hypen (and they are after all the guys who invented it) -- Nbound 11:04, 29 August 2006 (UTC)

English Only?

I can't seem to find any reference that states that this change is only being made to the English terms as the article claims. All German sources that I've checked seem to think that it applies to them as well. 131.181.251.66 04:40, 31 August 2006 (UTC)

The IAU resolution was issued in English. Translations in a great many languages were made immediately afterwards. The IAU did not say how 'dwarf planet' should be translated into any particular language. Michaelbusch 05:43, 31 August 2006 (UTC)