Talk:Dwarf planet/Archive 1

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Archive 1 Archive 2


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 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, 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:
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 (talkcontribs) .

  • 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. 04:08, 4 September 2006 (UTC)


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. - 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 - 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? - 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. 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.


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. 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

Someone proposed a merge from icedwarf. 03:36, 25 August 2006 (UTC)

I think it's user:Wetman


But isn't an ice dwarf necessarily a dwarf planet, and thus a subcategory of dwarf planet, because they need be larger than comets, which would make them into dwarf planets anyhow? 22:37, 25 August 2006 (UTC)


  • I'm neutral on the idea. 03:38, 25 August 2006 (UTC)
  • Oppose. "Ice dwarf" is a redundant article, but it ought to be merged not with Dwarf planet but with Trans-Neptunian object. Not all ice dwarfs (using the definition in the article) are dwarf planets, and at least one dwarf planet, Ceres, is not an ice dwarf. RandomCritic 03:56, 25 August 2006 (UTC)
Additional: The article Plutonian object which was hastily merged (without discussion) to Ice dwarf ought to be merged, instead, with Dwarf planet. I have reverted Plutonian object to its last pre-merger form so this can be done.
I have now merged the material from Plutonian object with Dwarf planet.RandomCritic 13:23, 25 August 2006 (UTC)
Update - The folks at Trans-Neptunian object didn't want "ice dwarf" either, mostly based on the text of the article which misidentified the term with "pluton" -- although before the IAU frenzy Ice dwarfs was a small redundant stub about TNOs, with nothing about planets or plutons in it at all. I'm removing both merger requests and restoring "ice dwarf" to its pre-IAU state -- perhaps the TNO people will reconsider it in a few weeks.RandomCritic 15:47, 25 August 2006 (UTC)
  • strong oppose this shouldnt even be a vote. this is a diffent group of celestial bodies.--Pedro 11:03, 25 August 2006 (UTC)
  • Oppose. Not all ice dwarves are dwarf planets, and this article alone seems decent enough to keep separately. --Nishkid64 14:29, 25 August 2006 (UTC)
  • Oppose. Ceres is a dwarf planet, and not an ice dwarf. They are not the same thing.Derek Balsam 15:01, 25 August 2006 (UTC)
  • Oppose Just because some body in orbit around the sun is classified as an Ice Dwarf does not guarentee that it is a Dwarf Planet. Just because what we have currently found to be Ice Dwarves also (for the most part) happen to be Dwarf Planets, does not mean that all of the Ice Dwarves that we find in the future will also be able to be known under that title. 15:19, 25 August 2006 (UTC)

Consensus Conclusion

Consensus is do not merge. 18:53, 31 August 2006 (UTC)

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. - 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


  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)


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)



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)


Hi, can we have an image of the three dwarf planets? Like Terrestrial planet size comparisons.jpg 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)


According to the fifth paragraph of this site <> , 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. 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)

mergefrom Candidate planet

Should we redirect Candidate planets here?


  1. Support -- Arch O. La Grigory Deepdelver 08:33, 4 September 2006 (UTC)


  1. Oppose Dwarf Planet is currently an IAU defined term. Candidate planets is not and should be merged with the 2006 redefinition of planet article which is where descriptions of failed proposals belong. Sophia 10:48, 4 September 2006 (UTC)
  2. Oppose, per Sophia. —Nightstallion (?) 11:13, 19 September 2006 (UTC)


See the related vote at Talk:2006_redefinition_of_planet#mergefrom_Candidate_planet and related comments at Talk:Candidate_planets#Merge_Suggestions.Arch O. La Grigory Deepdelver 02:32, 5 September 2006 (UTC)

Changed Spelling

To the "u" out of neighborhood. I don't know if thats the English spelling (as apposed to the American spelling) as near as I could tell it was a misspell. Feel free to change if I was wrong.

It's British spelling (probably international spelling in this case) and was used in the original wording. --Aranae 09:07, 1 September 2006 (UTC)

Many recent edits have converted fulfil (UK) to fulfill (USA) and vice versa. Not only is this a waste of time, it is also against wiki policy (somewhere). Come on guys, surely life is too short for this? Abtract 22:27, 15 November 2006 (UTC)

You're correct that it's a waste of time. I'd actually thought that my edits were maintaining the original version, but now that I look back through the history it's hard to determine which came first. Anyways, as you suggested, it's not a big deal. --Ckatzchatspy 22:40, 15 November 2006 (UTC)

Chart: volume

I removed km3 from the volume entry because only a ratio is displayed--unless someone has the actual volumes in km3 handy? AOB 22:19, 2 September 2006 (UTC)

Minor planet numbers

Looks like all dwarf planets have now been assigned with minor planet numbers. 1 Ceres, (136199) 2003 UB313 — and 134340 Pluto.--JyriL talk 16:02, 7 September 2006 (UTC)

Offering a different planet classification

The following seems to fall under the category of original research/soapbox and is therefore not suitable for inclusion in the article. Because of this, further discussion is also not needed here.Michaelbusch 16:02, 11 September 2006 (UTC)

The "dethronement" of planet Pluto from its position, as the outermost planet in our Solar system, evoked a sensational storm, not only in the astronomical society, but in the whole scientific community around the world and beyond, pro and contra.

The reason this problem has aroused was the discovering the new trans-Plutonian planet as Xena and many other "icy balls" in outer Solar system in the so called Kuiper Belt. To stop this "inflation" in the planet population, the International Astronomical Union (IAU) decided, in its Prague meeting, to reduce the number of newly discovered planets, including Pluto, which has been discovered about seventy years ago (1930), As follows: Under the new rules, a planet must meet three criteria: it must orbit the Sun, it must be big enough for gravity to squash it into a round ball, and must have cleared other things out of the way in its orbit. The Solar system, therefore, will maintain its original size. The "classical" Planets are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. These are the final eight members of the Solar system. Pluto has been excluded as a "dwarf" planet. This "new" astronomical concept of the Solar system, is based on the traditional model of the Solar system, upon the heliocentric conception, adopted, in the second half of the second millennium (XVI century) by Copernicus, Galilei and Kepler 500 years ago. This archaic point of view, leading to the theory of classical understanding the principal astronomical laws, built up the Solar system, as seen by the observations the orbit of the planets and satellites. My new updated proposition for understanding the composition of the Solar system, based upon modern astrophysics, is as follows: There are three groups of satellites around our Sun: The first one - the four giant gaseous "sub-stellar" satellites, namely: Jupiter, Saturn, Uranus and Neptune. Each of those satellites, like the Sun, is composed mainly of low density hydrogen and has greater volume then any other planet. They have rings around them, planet-sized satellites and small debris circling around them. ! The second group is composed of so called “Real Planets”, which are made of solid dense material. Their volume is about several thousand Kilometer in diameter (The planet Earth and Pluto also belong in this group). The third group is composed of small homogenous debris in the Kuiper Belt and other rings, such as the Asteroid Belt. Comets also belong to this group. Michael Popper, Taverne, Switzerland [user:michael_popper]

All that just because people cant let go of the reclassification of 134340 Pluto. Its a ball of rock among many in the Kuiper Belt. -- Nbound 11:17, 11 September 2006 (UTC)

  • Nbound that does not mean it is not a planet.--Pedro 11:18, 11 September 2006 (UTC)

No, it means precisely that, science needs a consistent and non-arbitary point to define things, Pluto didnt make the cut... goodbye Pluto... -- Nbound 11:28, 11 September 2006 (UTC)

I would have supported either the 12 planet or 8 planet plan btw, as long as the defining point was consistent -- Nbound 11:29, 11 September 2006 (UTC)

  • the first draft was, it is not now. I think planetary scientists should also form a proper international association and make their own definition: "The cism of planetary science" eheh. IMO, only planetary scientist should have a say on what's a planet. Or, in the other hand, turn this into real politics, because maybe tomorrow geologists will say Europe is a peninsula, not a continent. --Pedro 12:07, 11 September 2006 (UTC)

The main problem with the first draft (this is not my opinion btw) was that it was too open, it allowed what could possibly be hundreds of objects to be classified as planets, when only a tiny fraction of those were planets in any real sense (be that by perspective, or physical properties). It has been noted by many planetary scientists that there are really only 8 planets which dominate their area, while there are many more, which are planet-like but arent unique by any means, and often sharing orbits with other planetoids and asteroidal matter. This distinction is what the resolution was tryin to achieve... a defining point between the "planets" which dominate their surrounds, and the "planets" which while being planet-like do not. Its funny you say that because Europe is recognized (in conjunction with Asia) as Eurasia, they are really only separated by a historical line. See Also: Eurasian Plate -- Nbound 12:43, 11 September 2006 (UTC)

  • don't confuse planetary scientists with the broader "astronomer". I don't think most planetary scientists agree with this definition, but that's what I think. "clearing the neighbourhood" is something a planetary scientist will never think of for definition of a planet. Planetary scientists are most interested in physical aspects of the body proper. Eurasia is part of plate tectonics topic, continents aren't plates, Europe is a continent. that's why they (politians et al) can do the same for Pluto. Like someone said, the IAU can even vote to declare Pluto as a banana split. Should we (the world) accept it? too many?! There are much more stars than sand on Earth. it is the universe we live on. Pluto is a dwarf planet. Ok. Yesterday I told some friends that Pluto was no longer a planet, you can guess the answer, they though I was crazy. But don't focus on plutinos and the cubewanos (please!) and all that new kind of categorizations that is not really used broadly, articles on planets/moons and dwarf planets should focus on the object itself and little on other things that some astronomers like. If not, Pluto is also a planet.--Pedro 13:08, 11 September 2006 (UTC)

I think most planetary scientists do agree with the definition (hence why it passed the vote). clearing its orbit has everything to do with the characteristics of a planet, as it suggests a different path of "planetary growth" (via accretion) than these other objects which have become under the influence of the larger (and thus more gravitationally dominant) planets. I wont continue due to michaelbusch's nonsoapbox comment above but ill leave you with one thing: Should our science be driven by popular opinion or scientific theory? I know which id prefer :) -- Nbound 23:12, 11 September 2006 (UTC)

Newbie question

I quote: five orders of magnitude in Λ. What exactly is Λ? Why is it significant? Rwflammang 12:39, 14 September 2006 (UTC)

Added a basic explanation. Please keep in mind that a single point of view is presented here and a single model. Close to a violation of NPOV in my opinion. Eurocommuter 13:14, 14 September 2006 (UTC)

Color scheme of draft proposal/vote outcome diagrams

The "draft proposal" and "outcome of the vote" diagrams at the end of the article contain some light cyan text on a white background, which is virtually unreadable. I suggest that the diagrams use text colors that have more contrast from the background. - 15:23, 14 September 2006 (UTC)

Indeed. Hope it's a bit better now. Eurocommuter 21:54, 14 September 2006 (UTC)

Ixion, Sedna, Quaoar

I don't understand, we are waiting for the IAU to declare them dwarf planets, or...?--TheFEARgod (listening) 20:40, 14 September 2006 (UTC)

  • ...Small solar system bodies. ---Pedro 21:11, 14 September 2006 (UTC)

Dwarf planets names

Hmm several people here want to have pluto with its original name and the two other dwarf planets with the numbers

We must decide whether:

  1. they will be named with the numbers (1 Ceres)
  2. without (Ceres)

Let's decide it here. (the decision made should have no exception - Pluto for example)--TheFEARgod (listening) 21:54, 14 September 2006 (UTC)

I think the most common usage for these dwarf planets will be simply by their names: Ceres, Pluto, Eris, and the others that are to follow them into this category. If the mythological figure on which they are based is obscure enough (such as perhaps Sedna and Quaoar if they are elevated to dwarf planet), they should be placed by their name only. If a disambiguation is required then number-name is perferable to a parenthetical statement following the name because it is the official name of the object anyway. --Aranae 03:16, 15 September 2006 (UTC)

and one more question. I need a short explanation why Pluto doesn't need and other DPs need numbers??--TheFEARgod (listening) 10:39, 15 September 2006 (UTC)
Pluto was considered to be a planet until recently, although its status as a planet has been under increasing attack ever since 1978 (when Charon was discovered and showed that Pluto is much smaller than originally thought) and more so since 1992 (when the Kuiper Belt objects started being discovered). In fact Pluto lacked a minor planet number until this year, when it formally became cataloged as number 134340. The result is that Pluto has traditionally been described without a number (if only because it lacked a number). The time has come to change that, but the old habit is going to be hard to break. There are now related discussions going on at talk:Pluto and talk:136199 Eris. --EMS | Talk 15:11, 15 September 2006 (UTC)
Pluto handily beats the other uses of its name in name recognition right now. Therefore "Pluto" goes straight to the dwarf planet instead of a disambiguation page. The same can't be said for Ceres and Eris at present. The reason for the number is that it is a (the) technically correct name that needs to be at the beginning the article that also serves to disambiguate. If Pluto fades into obscurity in the future such that Roman Hades and/or Mickey's dog are equally well-known usages, then Pluto would also warrant a number to disambiguate. --Aranae 04:48, 16 September 2006 (UTC)

In favor of numbers included. While the number isn't the common name, it has just been established, so how can it be the common name? Also, I rarely hear anyone call Ceres "1 Ceres". That having been said, I am in support of including the numbers, as it is the official name. Being a part of WP:USRD, we've been debating what the names of the state routes should be. We've concluded that we should go by the official name (which is commonly used) but is not the most commonly used name. For example, most people refer to a state route in Pennsylvania as PA-39. But we chose to use the title Pennsylvania Route 39. I think the same should be used here. Instead of Ceres it should be 1 Ceres. Just like the other two dwarf planets, and others if the IAU should add to the list. --myselfalso 16:21, 15 September 2006 (UTC)

Having the numbers in the name is superfluous for anyone but an astronomer. This is not an encyclopedia for astronomers, but one for the general public. The full designation should be listed somewhere in the article, but the article should use the name that people, and the general news media, use. Saying that the number should be included is like saying that the cocaine article should be renamed as methyl 3-benzoyloxy-8-methyl-8-azabicyclo[3.2.1]octane-4-carboxylate. No-one other than a chemist would use that name, so trying to force it onto the general public is inherently illogical. aLii 17:27, 15 September 2006 (UTC)
As a planetary astronomer, I am biased, but the full designation is needed in many cases to remove ambiguity. Ceres, Eris, etc, are all mythological figures, so we would need rename all of the pages to something like Ceres (dwarf planet), Eris (dwarf planet), etc. Even that doesn't cover all cases, because there are a few duplicates in the catalog: Europa is both a moon (at Jupiter) and an asteroid (52 Europa) and two different asteroids are named Romulus. The cocaine analogy is false, because there there is near-zero potential for confusion and even a chemist would call cocaine cocaine.Michaelbusch 17:43, 15 September 2006 (UTC)
Are you honestly trying to tell me that while you're sitting around discussing dwarf planets over a cup of tea with other planetary astronomers, you actually use the term 134340 Pluto instead of simply Pluto? If that is what you are saying I don't believe you. Even If you were writing a scientific paper about dwarf planets my guess is that you'd state the full official name once, and then use the colloquial name for the rest of the paper. There is obviously more of a problem with naming the Eris article Eris, but Eris (dwarf planet) is fine. Re-direct pages can be made for all the various designations, but I think we should go with the simplest possible name for each body, not the most "officially correct" (whatever that means). For many asteroids, comets and even stars the simplest name will infact be a designation code, but for major bodies it doesn't seem necessary for codes to make up part of the article title. aLii 23:04, 15 September 2006 (UTC)
I'm in favor of names only where the body is not a point of confusion like the example between Europa and 51 Europa provided above. For example Pluto, Ceres, Eris... if you're talking planets there is no confusion about which giant space rock you're talking about. JohnnyBGood t c VIVA! 17:51, 15 September 2006 (UTC)

I'm in favor of names only because we have a new classification for a celestial body.--TheFEARgod (listening) 18:13, 15 September 2006 (UTC)

Comment - if we just choose the name only, then we will need to move Ceres. This will need to be approved on that page too. Arguably, Ceres, the dwarf planet, is no more well known than the goddess. Richard B 18:32, 15 September 2006 (UTC)

In favour of numbers - first off, the number serves to disambiguate the name, and according to the guidelines at Wikipedia:Disambiguation: "When there is another word (such as Cheque instead of Check) or more complete name that is equally clear (such as Titan rocket), that should be used." The parentheses option (i.e. putting "Ceres (dwarf planet)" is only second in the list. In addition, both dwarf planets and SSSB fall under the category of "minor planets", as evidenced by the IAU/MPC's handling of the number system. Furthermore, the existence of redirects and disambiguation pages means that you won't have to remember the numbers anyway. Chaos syndrome 11:44, 17 September 2006 (UTC)


I wondered how the different POV's which we all know from the newsmedia are sketched in this article. But as far as I can see the "unofficial" POV is not mentioned at all: only the recent majority-vote POV is mentioned. This despite the fact that the term was certainly not recently invented nor is it owned by any group. Thus for the time being, I put the NPOV marker. Harald88 11:31, 15 September 2006 (UTC)

The non-official POV is well mentioned in 2006 redefinition of planet where it belongs, this article is about the term dwarf planet, not the controversy of the recent redefinition -- Nbound

This article presents only one opiniated definition of planet vs dwarf planet, while we all know that a big disagreement exists about this matter. Purposefully omitting other notable POV's is definitely misinformation against WP:NPOV. Harald88 11:07, 16 September 2006 (UTC)
This article is about the term not the redefinition itself -- Nbound 11:23, 16 September 2006 (UTC)
That's fine - if indeed indicated as a term as introduced and used by a certain group of people. Let's make that clear. Harald88 12:27, 16 September 2006 (UTC)
The term is used by all but a few people, certain group does not do it justice -- Nbound 12:30, 16 September 2006 (UTC)

The numbers are roughly equal - several hundred on each side - and insufficient to be of more value than just that of a poll. Note that this doesn't liberate this article from the obligation to describe all notable opinions, especially within that same organisation. Thus one or two sentences about that, together with an appropriate link, are still lacking. Harald88 12:44, 16 September 2006 (UTC)

I now add such remarks as well as a link to the abovementioned article, and consequently I'll remove the NPOV banner. It's of course a matter of taste where such remarks fit best; the main point is to have them in there. Harald88 22:01, 16 September 2006 (UTC)

If no-one else has any major problems with NPOV on this article I will remove the tag in a while (to give people time to comment) -- Nbound 11:52, 15 September 2006 (UTC)

Concur: the term is official. NPOV should be put instead on Orbital domination section instead: it presents a single (while respectable, of course) model and opinion (see #Newby question). Other models and opinions (on whether the physical parameters alone, without orbital consideration should be defining characteristics of dwarf, uber, inter … planets) should be added, and in the meantime, the existing text NPOV’ed with in one model for example... One cannot read a single paper and build an article (Orbital domination) around it IMHO. Eurocommuter 12:07, 15 September 2006 (UTC).

I see your point, but the orbital dominance model seems to be the model the new planetary definitions are built around, it should get the attention of this article, though perhaps a short paragraph at the end outlining that this is not the only model, but the base of the current definition? -- Nbound 12:13, 15 September 2006 (UTC)

I have made a mention of other theories in the orbital dominance section, any elaboration on this though should really be in the main article of clearing the neighbourhood. -- Nbound 12:34, 15 September 2006 (UTC)

Well, I would expect that it could be as many ways to model orbital dominance as to skin the cat. I do not have any special interest in this field, but this Wikipedia article before by small addition/explanation could imply that the lambda parameter is as established as the gravitational constant. Just wanted to encourage editors to look for alternative models/papers. Or, to confirm that this model of dominance have been actually endorsed by IAU. If this is the case, please just quote the source related to IAU. Regards Eurocommuter 12:40, 15 September 2006 (UTC)

I'll leave the NPOV tags up as it may coerce an ethusiastic editor to find a reference to verify whether or not it is the IAU endorsed model of definiting oribtal dominance -- Nbound

I really do not believe anything is ‘official’ as a whole in this still on-going debate redefining Pluto (and the justification the existance of this definition). To call this stuff ‘official’ is pure POV conjecture. Nonprof. Frinkus 08:30, 4 November 2006 (UTC)

subpage on naming

In light of the 136199 Eris recently being renamed Eris (dwarf planet) and any renaming of Pluto being rejected, I have started Talk:Dwarf_planet/Naming. I hope to have editors from all of the "dwarf planet" pages use it to hammer out a coherent policy on this issue. --EMS | Talk 02:20, 17 September 2006 (UTC)

New Template for dwarf planet names

(from the Naming sub-page) You can now enter {{dp|Name}} and it will automatically bring up the correct minor planet number without you needing to look it up, but it will display only as the name. E.g. {{dp|Ceres}} will give Ceres i.e. [[1 Ceres|Ceres]].

These can be used mid-article to provide links to the correct article titles, without using redirects and saving time writing minor planet numbers in.

Only covers the dwarf planets - {{dp|Pluto}} will link to [[134340 Pluto|Pluto]] at the moment - just in case it ever changes - but you wouldn't need to currently use the template for links to the Pluto article - it's just at Pluto

The template can of course be amended if the naming convention changes e.g. if the IAU issues a new dwarf planet catalogue system - meaning that no links would have to be changed - just the template. Richard B 00:56, 20 September 2006 (UTC)

Ceres no longer considered an asteroid by the IAU

Some light on the mystery as to whether or not Ceres is still an asteroid: text from the IAU's website:

"Q: What is Ceres? A: Ceres is (or now we can say it was) the largest asteroid, about 1000 km across, orbiting in the asteroid belt between Mars and Jupiter. Ceres now qualifies as a dwarf planet because it is now known to be large enough (massive enough) to have self-gravity pulling itself into a nearly round shape."

"Q: Didn’t Ceres used to be called an asteroid or minor planet? A: Historically, Ceres was called a “planet” when it was first discovered (in 1801) orbiting in what is known as the asteroid belt between Mars and Jupiter. Because 19 th century astronomers could not resolve the size and shape of Ceres, and because numerous other bodies were discovered in the same region, Ceres lost its planetary status. For more than a century, Ceres has been referred to as an asteroid or minor planet."

--Ckatzchatspy 05:03, 22 September 2006 (UTC)

Article Naming - a new proposal

Hmm, it looks like no one mentioned here, that there is a new proposal for the naming of articles for the dwarf planets at Talk:Dwarf planet/Naming#A New Proposal. Nfitz 01:11, 2 October 2006 (UTC)

"Dwarf planet and other solar system categories" section

I've removed the "Dwarf planet and other solar system categories" section from the article pending discussion. Here is the text in question:

"The categorization of solar system objects into the three categories of planet, dwarf planet, and Small Solar-System Body established by IAU Resolution 5A does not supersede previous classifications based on other criteria, such as a body's location in the Solar System, its composition, or its history. The Resolution itself makes reference to the classes asteroid, Trans-Neptunian object (TNO), and comet (footnote 3).[1]"

"None of these classes (asteroid, TNO, comet) is coterminous with any of the categories of planet, dwarf planet, and Small Solar-System Body. They may or may not be subsets of the latter categories. The language in footnote 3 that Small Solar-System Bodies "currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies," although technically ambiguous, implies that "comets and other small bodies" are subsets of the category "Small Solar-System Body". The use of the word "most", however, indicates that asteroids and TNOs are sets that only partially overlap the category; this is consistent with the naming of asteroid 1 Ceres and TNOs Pluto and Eris as dwarf planets and not Small Solar-System Bodies. A reasonable conclusion is that Ceres continues to be the largest asteroid and Pluto and Eris continue to be Trans-Neptunian objects despite also being categorized as dwarf planets."

It appears that the text is not based on verifiable definitions, but instead sounds like the dreaded "original research". While it would be nice to have a concrete definition of what is what in the solar system, I don't think Wikipedia should be creating that definition. If anyone has thoughts on this, or (more importantly) can provide citations for the conclusions reached in the text, please add them. Thanks! --Ckatzchatspy 08:32, 3 October 2006 (UTC)

I agree that it is probably best left out. It's interpreting and drawing conclusions from the text of the IAU resolution etc, not merely setting out interpretations and conclusions made by others. Also, whether (for example) Ceres is still an asteroid is best dealt with in that article. Similarly for Pluto and Eris. --Cuddlyopedia 12:10, 3 October 2006 (UTC)


Archived talk down to the beginning of September 2006. RandomCritic 00:43, 16 October 2006 (UTC)

Lack of Clarity

Is a dwarf planet a planet that happens to be of type dwarf, or not a planet at all? For example, a berry is a fruit, but a fruit is not necessarily a berry; berry is just a subcategory of fruit. If it is not a planet, I a surprised there is no hyphen, because it dwarf looks to be an adjectives, and nothing more. It seems dwarf is a subcategory of planet, and this article does not explain this clearly, especially to lay people. Nonprof. Frinkus 20:41, 3 November 2006 (UTC)

"Dwarf planet" is that name of a type of solar system object. If the article doesn't say it's a subcategory of "planets", that's because that's not how it's defined. If it helps, think of it as one word that happens to have a space in the middle. TCC (talk) (contribs) 23:50, 3 November 2006 (UTC)
Is it good English to have two words work as one? With such an explanation, it probably would be difficult to get all school children to understand the precise difference between ‘planet’ and ‘dwarf planet’ and yet another possible contradiction in rules in English grammar. As for the science behind this (or severe lack thereof, real science is not a popularity contest and should not be determined by vote) ... “new planet definition that relegates Pluto to "dwarf planet" status is drawing intense criticism from astronomers. It appears likely that the definition will not be widely adopted by astronomers for everyday use, even though it is the International Astronomical Union's (IAU) official position.”. [from New Scientist Space] “"Alan Stern, who heads NASA's New Horizons mission to Pluto and works at the Southwest Research Institute in Boulder, Colorado, US, says the new definition is "awful". "The definition introduced is fundamentally flawed," he told New Scientist. "As a scientist, I'm embarrassed."”.

He goes on to say that only 4 of 8 objects in the IAU's new planetary definition meet their convoluted criteria (Earth and Jupiter for example, do not). He gives technical details for why that is. Another strong point was that “the new definition was pushed by people who are unhappy with having large numbers of planets” (very unscientific). All of that in addition that only astronomers were present, and less than 5% of the total IAU membership voted. Perhaps Richard Conn Henry likes to make a semantical (and only time will show how insignificant) victory to satisfy his own personal opinions.
So, given all of these numerous flaws, why does the main Pluto article now redefine Pluto as a ‘dwarf planet’ when frankly, I yet to see any real consensus (scientific or otherwise) nor any earth shattering supporting logic? Can I change that, or give both the title of ‘planet’ and ‘dwarf planet’ equal standing in all sections of that article?
Nonprof. Frinkus 08:27, 4 November 2006 (UTC)
Well, first off, you should probably pose that question over at Talk:Pluto rather than here, seeing as how it involves changes to that article. Secondly, I don't think the article is "redefining" Pluto - the IAU redefined it. Wikipedia, as an encyclopedia, bases its definitions of "planet" and "dwarf planet" on the decisions of the governing body for a particular field - in this case, the IAU. That doesn't mean that the article can't cover the controversy - in fact, that would be an important part of the coverage, and it is well represented. However, there is a real difference between writing about a controversy and participating in it. By doing what you propose, you would cross that line. (Just my two cents.) --Ckatzchatspy 09:34, 4 November 2006 (UTC)
Me controversial … moohey, sorry about that.  :-) Almost all of what I wrote there, was sourced in the same flavour (albeit not exact word for word due to copywrite) is not original by me, so I did not realize I was participating in it. And you are correct, this does not belong here … one question led to another, and I am not sure how to properly transition stuff over.
Ummm, is there a Wikipedia policy that states that each section of subject matter has only one official governing body to make decisions, and that this encyclopædia must be in lock step with that organization for the official take? Some of the complaints of scientists I mentioned there, is the fact some governing bodies could be much more narrow than the community directly researching that type of subject matter as a whole. Unless there is some official policy stating that one organization will be anointed master of each subject matter for official takes … does not Wikipedia participate in the controversy as well (by choosing sides for who gets top billing, even though both sides of issue might be represented when some areas)?
Nonprof. Frinkus 20:07, 4 November 2006 (UTC)

If a Dwarf star is a Star, should not a dwarf planet be a planet?

That's just a grammatical mistake, so it doesn't prove that a dwarf planet is a planet.

Nonprof. Frinkus 06:17, 6 January 2007 (UTC)

What's a grammatical mistake? Dwarf star or a dwarf planet? I believe IAU motivated it's decision by referring to an earlier mistake, but does one wrong rectify the other? I think this kind of terminology should be defined by linguists, not astronomers. Those fools seem to think language rules doesn't matter. I also think that we shouldn't take IAU too seriously, when they don't handle terminology seriously. Said: Rursus 13:54, 19 April 2007 (UTC)

Should this article explain why this definition is required?

Should this article on "Dwarf planet" explain the reasons why it is so important to have a separate definition for the term "Planet"? No where in this article does it seem to clearly justify the why this definition is so importantly required. Could I be wrong here? Nonprof. Frinkus 05:49, 5 November 2006 (UTC)

Doesn't anyone have a clear answer here? That would be helpful for my own research and for inclusion in this article.  :) Nonprof. Frinkus 06:17, 6 January 2007 (UTC)

"As defined, the term "dwarf planet" does not apply to other planetary systems." I think this statement does not make sense as it stands, nor does it's citation support the statement. The definition DOES apply to other systems just fine: if the body has cleared its orbit of most other mass, it is an extrasolar planet, if it has not then it is an extrasolar dwarf planet. There is possibly a problem insofar that extrasolar planets have highly elliptical orbits, so the concept of orbital clearance isn't easily applied, but that should be made clear. That concern would BTW also apply to any undiscovered very large bodies in our system with highly elliptical orbits.

Alternative Term

Is anyone else concerned that astronomers came up with the name 'dwarf planet' which is supposed to make things easier for the public and for schoolkids? Not only is it confusing to say that a dwarf planet is not a planet, but the name could make astronomers a laughing stock. Every smart ass kid in the classroom is going to say: 'Sir/Miss, dwarf planets, is that where dwarfs come from?' and all the kids will fall around laughing. Snow White and the seven Plutonians anyone? Somebody call Peter Jackson, his casting problems for The Hobbit (if it's ever made)are over - all he has to do is go to Pluto haha. It might well be a public relations disaster that would hold astronomers up to ridicule.

All joking aside, it is understandable that scientists like to have precedents for when they coin new terminology but 'dwarf planet' is not the answer. With all the talk of densities of rock and ice etc, the debate moved into the realms of geology and that is where the real precedents lie. Many terms in geology use the suffix 'ule' from Latin and Greek as a dimunitive. Here are some example- note that they have the relevant quality of roundness:

  • Globe - globule;
  • Sphere - spherule;
  • Grain - granule;
  • Node - nodule

Also of interest are some terms from biology.

  • An 'ovule' is an unfertilised or undeveloped seed (from Latin ovum), and
  • 'sporule' is a small spore. It may seem strange for astronomy to borrow from such a source, but with talk of stars being 'born and 'dying' etc, maybe it is not so strange.

How about Planetule to describe Pluto (?), Ceres et al.

To the general public it would be easy to understand as meaning 'a very small or 'undeveloped' planet or planet like object'. It would square the circle of describing something that's like a planet, but doesn't make the grade to being a fully fledged one.

As to how to distinguish a planetule from a planet, that's another day's work, but at least it would solve the 'Snow White' problem!Neelmack 21:08, 17 November 2006 (UTC)Neelmack

Wikipedia:No orginial research. Michaelbusch 20:30, 11 January 2007 (UTC)
I find the proposal very interesting, but I have to agree here is the wrong place to discuss it. You should contact your closest member of the IAU. I hope you will have success. Rgerhards 09:23, 12 January 2007 (UTC)

I emailed several members of the IAU but got no replies. Does anyone know of a suitable website or forum where I can post my suggestion for discussion? Neelmack 19:26, 13 March 2007 (UTC)

I think we need not take the so called terminology (scorn!) determined by IAU too seriously, just wait and see how the humankind use the word planet – I believe that faulty term won't be used, and Wikipedia is obligued to use terms in a way that reflect the actual usage. Said: Rursus 14:01, 19 April 2007 (UTC)
I remind both of you that this is the talk page for the article Dwarf planet, not a forum for discussion of the article's subject. For that debate, please work off-line. Michaelbusch (talk) 18:26, 19 November 2007 (UTC)


I archived the talk from September-October 2006. RandomCritic 12:11, 22 November 2006 (UTC)

Whether or not a dwarf planet is a planet.

i personally believe that dwarf planets should be considered planets because their relationship to planets is the same as that of dwarf stars to other stars and dwarf stars are considered stars. —The preceding unsigned comment was added by (talk) 18:44, 18 December 2006 (UTC).

According to this it isn't. Abtract 18:53, 18 December 2006 (UTC)
Dwarf star means many different things: white dwarf, red dwarf, brown dwarf. A white dwarf weighs within a factor of ten as much as the sun, as does a red dwarf, and both fused hydrogen at some point. A brown dwarf is different: there is no hydrogen fusion, the masses are much lower. If you wish, the relationship between a planet and a dwarf planet is like that between the Sun and a brown dwarf: one important physical boundary in mass has been crossed, but another has not. Personal opinion is also not grounds for inclusion in Wikipedia. Michaelbusch 19:24, 18 December 2006 (UTC)
Red dwarfs have a mass less than 1/3 of the sun--which is itself a yellow dwarf. But are we bere to discuss stars or planets? Arch O. La Grigory Deepdelver 17:26, 19 December 2006 (UTC)
I don't think that the claim "The category dwarf planet is not a subset of the category planet" can be defended. I feel there are clearly three categories: ("Dwarf planet", "nondwarf planet") both members of the set of planets, and "small solar system bodies." The reason that I say this is that the Earth is currently a nondwarf planet but will become a dwarf planet whenever some clutter (including human clutter and junk) intrudes onto our orbit, until th point the planet cleans it up again; while Pluto is a dwarf planet that could become a nondwarf planet is someone were to pop out there with a big net and clear up its orbit, and Neptune and Jupiter are dwarf planets because of the Trojans at their L4/L5 points. A planet can move from one category to another freely, without changing its own form in any way: and in fact, any dwarf planet, given enough time, will become a nondwarf planet by clearing its own orbit. It is silly to say that a planet can become a nonplanet just by changing the things it shares its orbit with, and vice versa. It is silly to say that two planets at eachothers' L3 points are automatically dwarf planets because they share the same orbit. It is acceptable, however, to say that the categorisation of the TYPE of planet changes depending on its orbital companions, though, just as it can change from being a binary planet to a regular one without changing its essential planettiness. 22:07, 16 October 2007 (UTC)
You're letting linguistics fool you. By the IAU's definition of the two terms, dwarf planets are not planets. Also, it'd take a lot more than a few billion tons of debris in our orbit for the Earth to be classified as a dwarf planet. (Mars would be at greater risk.) Look at the cleared the neighbourhood article for more on that. Ben Hocking (talk|contribs) 22:26, 16 October 2007 (UTC)

The Solar System or Our Solar System

Currently, the second paragraph says:

The term "dwarf planet" applies only to objects in the Solar System.[2] and is quite distinct from "planet" and "small solar system body".

I would like to suggest changing this to

The term "dwarf planet" applies only to objects in our solar system,[2] and is quite distinct from "planet" and "small solar system body".

Yes, I am aware that "the Solar System" (with capital letters) refers to our own solar system, as opposed to any other solar system in the universe. However, the average man on the street might not be aware of such a distinction. Since the intent of this paragraph is to say that the term "dwarf planet" only applies to our own solar system, I feel that it is appropriate for us to make this point clearer in this one specific instance.

I had been bold and made this change myself, but was reverted by Ckatz. I'm therefore bringing the discussion to the Talk page. (Incidentally, Ckatz also restored the incorrect full stop before the reference marker, which I had replaced by a comma.) Bluap 19:24, 5 January 2007 (UTC)

Sorry if it wasn't clear, but I think you misunderstood my edit summary. What I meant was that there is only one system that is properly referred to as "solar" - ours, the "Sol" system. There aren't other "solar systems", so using "our" would be incorrect for either "Solar System" or "solar system". It also means that when we say a term such as "dwarf planet" applies only to "the solar system", we are being specific. That was the basis for undoing your edit. (My apologies for not noticing the comma - minor changes in punctuation aren't easy to see in the diffs.) --Ckatzchatspy 19:53, 5 January 2007 (UTC)
Ahh - I see that I was getting confused between solar system and planetary system. (Interestingly stellar system redirects to star system, while I would have thought that a redirect to planetary system might have been more appropriate.) I'll get my thinking cap on, and find a new way of wording those couple of paragraphs. Bluap 21:20, 5 January 2007 (UTC)
"Dwarf planet" … does this definition only apply to this (Sol's) solar system … and is not used for any other planetary star system found in space? I am seeking clarification, thank-you. Nonprof. Frinkus 06:13, 6 January 2007 (UTC)
As per the article (third paragraph), "As defined, the term "dwarf planet" does not apply to other planetary systems." Hope this helps... --Ckatzchatspy 06:27, 6 January 2007 (UTC)
Oops, thank-you very much.  :) I thought that was an err, because I've been dumbly lost about the logical requirements for a new yet so awfully specific category, other than naming rock/ice balls to big to ignore. I will update my numbers, merci. Nonprof. Frinkus 06:29, 7 January 2007 (UTC)

New dwarf planet

..According to BBC. See title:

--TheFEARgod (Ч) 14:24, 17 January 2007 (UTC)

I think the BBC made a mistake on the headline... I couldn't find any mention online about it being reclassified. Potentially, yes, but that dates back to the fall. --Ckatzchatspy 17:40, 17 January 2007 (UTC)
That article is very badly garbled (see Talk:2003 EL61). EL61 is not classified as a dwarf planet by the IAU. Michaelbusch 19:20, 17 January 2007 (UTC)
Besides, classifying anything as a "dwarf planet" is a mistake. Its a planetary body, the size of Pluto. Said: Rursus 14:02, 19 April 2007 (UTC)

Eris' Mass

Can we get a citation for Eris' mass? I have not been able to verify this figure anywhere. All other sources say that it is unknown and astronomers are going to use the moon's orbit to calculate the mass. Notably, the Eris page does not give a figure, either. I'd love to be proven wrong; I just need a source. -- Joshua BishopRoby 00:40, 3 February 2007 (UTC)

I just added the citation, to Mike's 2006 paper on satellites of KBOs. Michaelbusch 00:52, 3 February 2007 (UTC)
I added it to the Eris article as well. Michaelbusch 00:57, 3 February 2007 (UTC)
From the cited article: "One faint source is seen near 2003 UB313 (Eris). ... We thus conclude that the source is a satellite moving with 2003 UB313. With only a single observation of the satellite of 2003 UB313, we cannot yet measure or constrain the mass of 2003 UB313, but we can estimate likely orbital parameters to aid further study." (emphasis mine) The article is about the sighting of the satellite, not the measurement of its orbit or the calculation of the dwarf planet's mass. -- Joshua BishopRoby 01:05, 3 February 2007 (UTC)
Further in the article, they estimate Dysnomia's period as 14 days. I asked Darin Ragozzine, one of Mike's students, if they had an orbit and consequently a mass & density, and he told me they did, and referenced that paper. It may be that I mis-understood him with regards to the reference, but they have the period and the mass. Michaelbusch 03:32, 3 February 2007 (UTC)
Alright, but you can't really cite the conversation that you had with an astronomer. I assume you mean the following passage: "If the semimajor axis is 14% greater than the current separation, and if 2003 UB313 has the size estimated by assuming an albedo and density similar to Pluto's (Brown et al. 2005a), the satellite will have an orbital period of approximately 2 weeks." They're not deriving the mass of Eris based on the orbit, they're deriving the orbit based on the mass of Eris, assuming Eris has the same albedo and density as Pluto, which is a mammoth assumption to make. Michael, can you provide a citation for the mass of Eris, not an estimate of the mass of Eris, or shall we put 'unknown' in there because the mass is, in fact, unknown? -- Joshua BishopRoby 17:40, 5 February 2007 (UTC)
They have the orbit now. I will check for more recent references. Note: we will never have anything other than an estimate for the mass of Eris or any other planet. Michaelbusch 18:05, 5 February 2007 (UTC)
The relevant paper would be M.E. Brown et al., 2007 in prep., which will be a paper giving the mass of Eris. It has not been published yet. Given this, we should place estimated tags (the mass and density given follow from the size and Dysnomia having a 14 day period. Presumably the paper will be more precise). Michaelbusch 18:27, 5 February 2007 (UTC)
Michael, could you please check out the recent addition to Eris (dwarf planet) (specifically the new sub-section "Mass and Density"). I suspect it could use a rewrite, but as it pertains to what you're discussing here, you're probably better suited to check it. Thanks. --Ckatzchatspy 20:19, 5 February 2007 (UTC)
I cleaned it up some. Hopefully, Mike will put out his paper giving the better mass value soon. Michaelbusch 20:25, 5 February 2007 (UTC)


I've noticed that the table showing the dwarf planets and the table showing the dawrf planet candidates do not match, on the dwarf planet table the names of the categories follow the Y-axis along the left while the candidate table has its category names along the X-axis at the top. Could someone change these two tables to make them similar? Ryan shell 18:58, 9 April 2007 (UTC) 18:57, 9 April 2007 (UTC)

That won't really do, both tables have a label column and three content columns, if either one is transposed, there will be far too many columns for the data to fit a sane web page view. Leave it as is. 15:35, 10 April 2007 (UTC)

4 dwarf planets?

I've been reading a special ASTRONOMY magazine, the 50 Greatest Mysteries of the Universe, and it says that the solar system has eight planets and 4 dwarf planets. Is it that they've made a typo error, or is it just me cause this article still mentions only 3 dwarf planets. — Alastor Moody (T + C + U) 04:19, 22 May 2007 (UTC)

It's not a typo exactly. It's a common enough statement. Loosely it's true anyhow. Pluto and Charon orbit each other. The IAU because it had two proposals mixed people up. You'll also see some include already without IAU approval other planetoids too like Sedna. Yisraelasper —Preceding comment was added at 11:35, 1 January 2008 (UTC)

Dwarf planet

(I moved this from my talk page in case anyone else wants to participate)

Hello... sorry, but I had to revert your edit at Dwarf planet. Charon is a unique case in that it is thought to possibly be part of a double-planet system (well, double dwarf planet now), based on Charon's large size relative to Pluto. This is not official, as the IAU has made no formal decision in this regard. However, it has been mentioned as a possible candidate for dwarf planet status, and was actually under consideration for designation as a planet under the initial IAU proposal last August. Hope this helps. --Ckatzchatspy 07:45, 11 June 2007 (UTC)
P.S. Sorry about the lack of an edit comment at Dwarf planet - my bad.

Thank you for your courteous explanation, but I'm actually aware of these facts. Since the IAU hasn't made an official ruling, Charon is still orbiting Pluto (similar to how Pluto was still a planet while the debate about it's status carried on, and it changed whenn they made it official.) I agree with the proposal because the barycenter of their interaction is actually not inside either one, whereas the Earth/Moon barycenter is inside the diameter of the Earth making it obvious that the Moon is the one orbiting the Earth. However even though the proposal makes sense we ought not act like it has already been announced. Anynobody 07:57, 11 June 2007 (UTC)
Fair enough - the remaining mention of Charon under the table of candidates is probably enough (and less confusing than the text you removed later in the article.) Cheers (and thanks for the nice note on my talk page!) --Ckatzchatspy 08:34, 11 June 2007 (UTC)
You're very welcome, I was thinking that mentioning the discussion in the IAU about Pluto/Charon and a brief explanation of why they are possibly(probably IMHO) not in a d. planet/sat relationship would be informative(with a source of course). I was just browsing when I came across the basic issue we're discussing and hadn't planned to do much editing here, right now I'm just taking a quick break from the articles I am editing to see what else is going on Wikipedia so if you want to write something about it in it's own subsection of candidates I'd say go for it. (Reason for giving it a subsection is dwarf planet rule four is no sats so it needs to be made clear this is under debate.) Anynobody 09:05, 11 June 2007 (UTC)