Talk:Kuiper belt

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Pronunciation of Kuiper[edit]

A website about the Dutch pronunciation of names is linked as a source reference for the pronunciation of "Kuiper". Nevertheless, the English pronunciation is used in this article. In Dutch, the "ui" digraph is IPA: [œy], therefore I believe that "Kuiper" should be IPA: [ˈkœypər]. – Ilse@ 13:13, 15 July 2008 (UTC)

Well, the Dutch page has a recording of someone pronouncing "Kuiper," and he pronounces it "Kyper". Scroll down to where it says "scientists". Serendipodous 12:23, 17 July 2008 (UTC)
The IPA transcription is original research. No IPA is given on the linked site. Besides, the English name Cowper is cognate with Kuiper. I don't think there's any greater authority.--Rfsmit (talk) 22:01, 10 February 2010 (UTC)
I have always heard it pronouned as "Kaiper", which the article appears to be consistent with. -RadicalOneContact MeChase My Tail 22:04, 10 February 2010 (UTC)
Pronunciation discussion copied from its original location

Verbatim, below. Iridia (talk) 01:11, 21 April 2009 (UTC)

I've followed your advice and read, but the only discussion I see regarding the pronunciation of Kuiper is, in which Ilse@ confirms my correction, and Serendipodous's reply that the mentioned website has Kuiper pronounced as Kyper is wrong, it is clearly pronounced [œy], which is correct, see [œy] being not a native vowel in English may have caused this confusion. —Preceding unsigned comment added by Upquark2 (talkcontribs) 10:32, 20 April 2009 (UTC)

You claimed by your IPA link that it was the English pronunciation, which by your own admission is impossible. The Dutch pronunciation is provided in Kuiper's bio. kwami (talk) 10:46, 20 April 2009 (UTC)
OK, now I'm confused. Do you mean that in English, non-English names should be pronounced as if they were English? So Kuiper should be pronounced /ˈkaɪpər/ while it's actually a Dutch name? Confusing... but if it's the case, thanks for having learned something new. Upquark2 (talk) 10:57, 20 April 2009 (UTC)
Sigh. Please check that Dutch link again. If you go down to where it says "scientists", Gerard Kuiper's name is listed next to an audio file. Listen to the audio file, and the voice clearly says, "kyper." Presumably, Kuiper changed the pronunciation of his own name when he went to the States and, since he was in the States when he wrote his paper, it follows that that was the pronunciation he used at that time. Ergo, it is pronounced "Kyper." Serendipodous 11:14, 20 April 2009 (UTC)
Sorry, but the voice (native Dutch speaker) really says [œy], like 'ui' should be pronounced in Dutch. I agree it's close to 'Kyper', though. Upquark2 (talk) 11:41, 20 April 2009 (UTC)
Even if that weren't the case, his name has become fully anglicized by English-speaking astronomers, and we would still use their pronunciation. kwami (talk) 11:35, 20 April 2009 (UTC)
Reasonable argument, I can live with that. Upquark2 (talk) 11:41, 20 April 2009 (UTC)
The problem is that people, when told not to pronounce it "Kyper", tend to pronounce it "Koyper", as an analogy to "Huygens", so it's best, for English speakers anyway, to say "Kyper." Serendipodous 10:04, 24 April 2009 (UTC)

Fair enough that the name got Anglicized and therefore now rhymes with "viper" (as mentioned in the article), whereas in fact it does NOT rhyme with viper. I would suggest to at least add the original Dutch pronunciation to it. Something like this: (pronounced in English /ˈkaɪpər/, rhyming with "viper" and originally in Dutch: /'kœypər/). For Dutch people there is a big difference between aɪ and œy. Baske77 (talk) 21:18, 31 January 2010 (UTC)

Is there some way to indicate the difference to English speakers? Because I have listened to that word hundreds of times and I still can't hear it. Serendipodous 23:04, 31 January 2010 (UTC)
I don't think there is an easy way to indicate to native English speaking people how the sound is significantly different for Dutch people. As the English language does not have the sound it is hard to hear it, I think. In favour of my suggestion I would like to point you all to the article of Christiaan Huygens (also a Dutch name, with the same sound in it) Christiaan_Huygens Where indeed both the English and the Dutch pronunciation are mentioned. I think a similar construction would be good for the Kuiper Belt article. Baske77 (talk) 12:30, 2 February 2010 (UTC)
The Huygens article has "hy-gens" for the English and "hoy-gens" for the Dutch, which sound very different to English ears ("by"/"boy"). The Dutch pronunciation site I linked to sounds almost exactly like "ky-per"Serendipodous 14:01, 2 February 2010 (UTC)
Doesn't matter. That's Howgens, this is Cowper (heh heh). Your English ears aren't attuned to Dutch pronunciation, the same way Chinese ears have great difficulty distinguishing L and R; the same way my Northern English ears have great difficulty distinguishing Southern English A and I.--Rfsmit (talk) 22:12, 10 February 2010 (UTC)
My problem with this is that a lot of English speakers think that Kuiper should be pronounced like "koy-per", which doesn't appear to be the case. If I just include the recommended Dutch pronunciation without some kind of example, people might come away assuming it should be pronounced "koy-per". Serendipodous 16:25, 11 February 2010 (UTC)
Indeed, since the word is fully anglicised, the Dutch pronunciation is irrelevant in this article which is about the Kuiper Belt. People can go to the article on Kuiper, the man if they want to know how to pronounce the name of the person from whom the Belt's name comes. Ashmoo (talk) 23:37, 23 March 2010 (UTC)
Just a quick thanks for having the pronunciation in this article. I've always wondered and finally followed-up on my curiosity. – Kerαunoςcopiagalaxies 22:05, 26 May 2010 (UTC)
I don't want to argue here about the anglicised pronunciation of Kuiper, I only want to give some final information about the Dutch pronunciation. I'm Dutch, and I've met many people with English as their native tongue. Among them some who speak nearly accentless Dutch, but they allways 'give themselves away' in their pronunciation of the Dutch 'ui'. They simply can't get it done. It's not oy as in boy, neither y as in by. For a Dutch man's ears, these two suggestions don't even come close to what it should be. To be complete: uy is an old spelling of ui, and it's pronounced exactly the same way in modern Dutch (we can't be sure of the 17th century pronunciation).Dunglisher (talk) 20:47, 30 April 2012 (UTC)



""In the region between 40 and 42 AU, for instance, no objects can retain a stable orbit over such times, and any observed in that region must have migrated there relatively recently.[40]

Classical belt

Between approximately 42–48 AU, however, the gravitational influence of Neptune is negligible, and objects can exist with their orbits essentially unmolested"".

this is seem to me contrary, i don`t understand the objects of Kuiper belt at distance between 40 and 42 AU from the sun have stable or unstable orbits! --عباد مجاهد ديرانية (talk) 10:57, 22 February 2010 (UTC).

40<--->42 = not stable. 42<---->48 = stable. Is there a contradiction? HumphreyW (talk) 11:22, 22 February 2010 (UTC)
The 40-42 AU can be unstable (over the age of the solar system) due to resonance perturbation by Neptune. Anything in a 2:3 resonance with Neptune (39.5AU from the Sun) will have a mild eccentricity. Beyond 42AU the strong 2:3 Neptune resonance will not perturb/excite you. But all of this is also a function of eccentricity and inclination. The 1:2 resonance is near 48AU. -- Kheider (talk) 14:04, 22 February 2010 (UTC)

ah sorry, may i was sleepy --عباد مجاهد ديرانية (talk) 08:00, 23 February 2010 (UTC).

How to treat Eris[edit]

Taken from the Kuiper belt article (To be a KBO or not to be):

  • It is home to at least four dwarf planets – Pluto, Eris, Haumea and Makemake.
  • Scattered disc objects such as Eris are KBO-like bodies with extremely large orbits
  • Eris, the recently discovered object now known to be larger than Pluto, is often referred to as a KBO, but is technically an SDO.
  • The largest KBO is Eris, discovered in 2003
    -- Kheider (talk) 20:48, 22 February 2010 (UTC)
Someone keeps adding Eris to the Kuiper belt. Eris should not be in the Kuiper belt because the MPC does not consider it part of the Kuiper belt. Serendipodous 20:52, 22 February 2010 (UTC)
Semantics :) As long as wiki is consistent. I know Mike Brown even treats centaurs as KBOs, so yes mileage can vary. -- Kheider (talk) 20:59, 22 February 2010 (UTC)
So is the definition of planet but people seem to care about that. :) And yes, wikipedia should be consistent. I only wish the IAU would get its act together and define the Kuiper belt already. Serendipodous 21:00, 22 February 2010 (UTC)
  • Hi world: for what it is worth, working astronomers generally call everything with a semimajor axis outside of Neptune but inside of the Oort cloud a Kuiper belt object. The distinctions between things like SDOs and resonant objects etc. are dynamical, not physical. Leaving Eris out of a list of KBOs is very very odd. -Mike Brown — Preceding unsigned comment added by (talk) 21:33, 9 September 2011 (UTC)
Well, Mike, assuming you are Mike, maybe if you can convince the IAU to drop the absolute magnitude criterion for dwarf planets, you could also convince them to change their definition of the Kuiper belt. :) Serendipodous 04:35, 10 September 2011 (UTC)
That's only for naming purposes. Magnitude is not part of the definition of a DP. — kwami (talk) 05:18, 10 September 2011 (UTC)
BTW, on Mike's site he says that Sedna is not a KBO because it orbits outside the belt.[1]
Papers such as this one do speak of the scattered disk vs. the main KB and clearly imply that the SD is part of the KB too. But they do say that Sedna is beyond the KB. — kwami (talk) 15:50, 10 September 2011 (UTC)
This discussion has been had. Many times. see here. Again, the authority is the IAU. Serendipodous 16:23, 10 September 2011 (UTC)

Size distribution[edit]

The source from which the power law is taken says that dN/dD ∝ Dq, while the formula in our text says -q. Is it a mistake or have I misunderstood something? Jan.Kamenicek (talk) 09:18, 9 May 2010 (UTC)

The size distribution can (and is) defined in many different ways. Saying that dN/dD ∝ D-q and q=4 is equivalent to saying dN/dD ∝ Dq and q=-4 or even dN/dD ∝ D2-3q and q=2 as some authors may write it. So long as the article is consistent I don't think this matters too much. AstroMark (talk) 13:12, 9 May 2010 (UTC)
No, if you look int the source, it says that dN/dD ∝ Dq and that q=4 (not -4), so it is something completely different from what there is in this article. Jan.Kamenicek (talk) 19:06, 9 May 2010 (UTC)

I think there is a mistake (typo) in Bernstein et al. There should be minus, otherwise the number of objects would grow with object size which is obviously not the case. Bernstein refers to another source: Trujillo and Brown, The Radial Distribution of the Kuiper Belt, 2001. It says "number of objects between radius r and r+{\mathrm d}r following \propto r^{-q}{\mathrm d}r" and all discussed vaues of q are positive. --Egg 06:20, 11 May 2010 (UTC)

AstroMark is correct, however q is generally used in this exact context as dN/dD ∝ D-q. In Bernstein et al. it is dN/dD ∝ Dq on p. 1365, but it is D-q when mentioned in the discussion on p. 1380. q's value is discussed as positive in the literature. See Fraser et al. (2008) if anyone wants to go through the full thing and see discussion of the current best-known q value. Iridia (talk) 12:18, 11 May 2010 (UTC)

Thanks everybody for their answers. Jan.Kamenicek (talk) 18:23, 11 May 2010 (UTC)

Capitalization of "Belt"[edit]

I feel very strongly that this article should make reference, both in its title and throughout its text, to the Kuiper Belt. The name "Kuiper Belt" is the unique name of a unique thing, like the Isthmus of Panama, the Sea of Cortez, the Bering Strait, or Vancouver Island. We may consider all of these to be compound proper nouns. The same holds true for the Oort Cloud. If one goes to one will find "Kuiper Belt" and "Oort Cloud" exclusively. NASA is right, of course! Writtenright (talk) 03:37, 21 June 2010 (UTC)writtenright

If we did that, then we'd have to call the asteroid belt the Asteroid Belt and I don't think there's a consensus to do that. Serendipodous 04:41, 21 June 2010 (UTC)
I'm not sure if it's necessary to capitalize "belt" in this case; I can see both sides of it... But the Kuiper Belt was named for someone, whereas the asteroid belt wasn't -- it's just a belt of asteroids, hence the name. Omnedon (talk) 04:58, 21 June 2010 (UTC)
Seems to me both are equally justified/correct, and WP just happens to have gone for Kb. Rothorpe (talk) 20:53, 9 August 2010 (UTC)
This isn't a decision for WIkipedia editors to make -- the answer is how is the capitalization most standardly found in dictionaries and authoritative scientific print publications. Unfortunately I'm finding "Kuiper belt" in one dictionary, which does seem to contradict its composite-noun use (e.g. you won't find "The Kuiper belt of comets...", or "The Kuiper is a belt of..."). But not up to me. If "Kuiper Belt" is sometimes found in authoritative sources, then it's "The Kuiper belt (sometimes Kuiper Belt)...". Also to be dealt with: "Kuiper belt objects", capitalized KBOs (which certainly sounds like a composite entity and not a phrase, but...). — Preceding unsigned comment added by (talk) 04:00, 3 November 2012 (UTC)

A subtle difference[edit]

"Originally considered a planet, Pluto's position as part of the Kuiper belt has caused it to be redefined as a 'dwarf planet." reads as Pluto was redefined whereas it wasn't, planet was. JIMp talk·cont 19:23, 22 November 2010 (UTC)

changed to "reclassified". Serendipodous 22:07, 22 November 2010 (UTC)

the number of known Kuiper belt objects (KBOs) has increased to over 9000[edit]

guys, over 9000 is a 4chan meme and the source "DBZ #1.28" is an episode of Dragon Ball Zee.Hexrei2 (talk) —Preceding undated comment added 04:59, 4 March 2011 (UTC).

That's really embarrassing. I can't believe no one here noticed it. Thanks for the headsup. Serendipodous 09:01, 4 March 2011 (UTC)

The solar wind[edit]

It is supposed that the solar wind moves direct planetary orbital .but it might be all around any quarter of sun , then we can suppose that the kuiper belt be spherical round solar system (not ring ). is it because of Einshtein general relativity that the solar wind have to move in such direction?--Akbarmohammadzade (talk) 05:31, 25 June 2011 (UTC)Iran

--Akbarmohammadzade (talk) 09:03, 26 June 2011 (UTC) well the O'ort belt is far from us , but we can see the effects of Kuiper belt where that first send water here to earth. ( in fact I am studying about the effects of solar wind on production of water in solar system , which cased the existence of life in this system)Akbarmohammadzade (IUST)--[[ Special:Contributions/|]] (talk) 08:52, 26 June 2011 (UTC) — Preceding unsigned comment added by (talk)

The Kuiper belt is a belt. The Oort cloud, is, presumably, a sphere. Serendipodous 09:24, 26 June 2011 (UTC)

Power law 3? Or 4?[edit]

What is the exponent in the power law? The text states "q = 4 ±0.5" but that is immediately followed by a numeric example "there are for instance 8 (=2^3) times more objects in 100–200 km range than objects in 200–400 km range. In other words, for every object with the diameter of 1,000 km (621 mi) there should be around 1000 (=10^3) objects with diameter of 100" which seems to be using an exponent of 3. Geoffrey.landis (talk) 18:15, 2 September 2011 (UTC)

  • q refers to the differential power law, i.e. dn/ds ~ s^{-q} , while the latter is using cumulative number in a range, i.e. dn/ds Δs - so they're in agreement. WilyD 18:22, 7 September 2011 (UTC)


"Kuiper" is not an English sound and WP:PRON also says that such usages only may be useful. The basic concern of WP:PRON is mere IPA. The addition of rhyme in the case of this article is redundant and makes Wikipedia look like an elementary school rhyming dictionary, which it is not. Also, "viper" is not a welcoming word for the lead. Brandmeistertalk 10:04, 27 May 2012 (UTC)

Your issues with its addition appear to be principally aesthetic rather than practical, and I don't really think aesthetics are worth fighting an edit war over. So in any case I'm grateful you finally decided to take this to the talk page. The rhyming pronunciation is for Kuiper's Anglicised name, which is different from the Dutch original. You could argue that it is not strictly necessary, but it saves the reader a minute or so of clicking and reading small print, so I think it helps. Serendipodous 10:09, 27 May 2012 (UTC)
The IPA template provides instant pronunciation hints by just pointing to with the cursor, so even if a person doesn't know what IPA is, (s)he would easily get it. A rhyming word often clutters the lead, where the reader may want to instantly skip to the text. Personally I don't think "viper" or any other rhyming word here is vital for the article (or is a major improvement). Brandmeistertalk 10:26, 27 May 2012 (UTC)
Tell ya what. How about a tie-break? Let someone else post, and whichever side that person agrees with, that's what we go for? Serendipodous 11:15, 27 May 2012 (UTC)
I don't mind. Brandmeistertalk 11:46, 27 May 2012 (UTC)
I suspect a lot of kids are drawn to this article, and few of them will be familiar w the IPA. So IMO giving a rhyme is useful. If not "viper" (though kids would probably like that), there "hyper", "piper", "riper", "wiper". — kwami (talk) 10:42, 7 January 2013 (UTC)

Update, extension request[edit]

Could someone update the histogram [2] to include the objects found since 2007, and ideally extend it on the right to 55 or 60 AU, so that the "Kuiper cliff" is more clearly visible? Thanks! --Roentgenium111 (talk) 19:57, 12 December 2012 (UTC)

Like this? It's not that visible by eye - the R^4 detection probability is still dominant; plus, including scattered objects washes it out. But the MPC does, so I have to. WilyD 12:02, 13 December 2012 (UTC)
@WilyD: That looks great, thanks! If you could give the data list you used as a reference, I'd like to add it to the article.
I think this is a list of just the Kuiper-belt objects (in spite of the list's name), BTW; it doesn't include SDO's like Eris or Sedna. --Roentgenium111 (talk) 22:40, 2 January 2013 (UTC)
That is indeed the list I used. If my word choice was unclear, "Hot classical" objects wash out the Kuiper cliff, then, since they're just scattered disk objects. But until someone gets around to writing a paper on the point, I think Wikipedia is stuck with this. WilyD 08:17, 3 January 2013 (UTC)
I see. But WP seems to consider "hot classical objects" to be KBOs as well, according to Classical Kuiper belt object. So your data list is as good as it can be, apparently. --Roentgenium111 (talk) 20:28, 6 January 2013 (UTC)
As with most things to do with the outer solar system, the terminology is a pain in the friggin arse. We have very little to go on and there isn't much of a call for any kind of standard as of yet. So the IAU's half-baked "definition" is pretty much all we can use. Serendipodous 21:35, 6 January 2013 (UTC)
Yeah, I know. The literature and (correspondingly) most experts do too. But it's wrong, so it screws up the plot, and bothers me. "Someone" will have to fix it there before we fix it here though. WilyD 08:20, 7 January 2013 (UTC)

Correction to "Kuiper cliff" Section[edit]

Paragraph 2, sentence 1 says "Earlier models of the Kuiper belt had suggested that the number of large objects would increase by a factor of two beyond 50 AU . . ." If it's a cliff, shouldn't this say decrease instead of increase? — Preceding unsigned comment added by JKW (talkcontribs) 12:42, 16 April 2013 (UTC)

Yes. If you would read it more carefully, then you would see that it says that it does decrease. The sentence you quote describes what people expected to find. --JorisvS (talk) 12:45, 16 April 2013 (UTC)
Ah, yes, you're right. I read the passage too quickly. Thank you for correcting me, and thanks for the outstanding article. Please delete this talk section since it adds nothing useful.--JKW (talk) 15:53, 16 April 2013 (UTC)


In the introduction's second paragraph, the first line reads a bit weird: "Since the belt was discovered in 1992,[6] the number of known Kuiper belt objects (KBOs) has increased to over a thousand, and more than 100,000 KBOs over 100 km (62 mi) in diameter are believed to exist.[7]" If the number of large objects are over 100,000, then of course the total number of objects are over 1,000: that seems uninformative. I have no idea what the correct numbers are though, just wanted to point it out. — Preceding unsigned comment added by CBoeckle (talkcontribs) 15:54, 16 December 2013 (UTC)

  • 1000 is the number of known objects (it's about 1500), 100 000 is someone or another's guess at the number of large objects. WilyD 16:04, 16 December 2013 (UTC)

We need to update our Kuiper belt graphs[edit]

There's a collection of them over at the Commons. Most haven't been updated since 2008. In particular the main image needs redoing with new info. Unfortunately I don't have the skills to do this. Serendipodous 13:25, 10 December 2014 (UTC)

Just the same plots, more or less, with newer data? WilyD 14:21, 10 December 2014 (UTC)

Actually, the total number of discoveries since that plot was made ain't many (though it says 2012?) WilyD 14:56, 10 December 2014 (UTC)

Really? As far as I know the main image hasn't been updated since 2007, and there have been some pretty extensive surveys done since then. But hey, you know better than me, and if you think the graphs don't need updating, I'll take your word for it. Serendipodous 16:27, 10 December 2014 (UTC)
Well, this is a vs i with symbol-size corresponding to H today. WilyD 16:58, 10 December 2014 (UTC)
Hm. Doesn't seem that different, though it's hard to tell because the original is so squashed. Your image probably deserves to replace it on aesthetic grounds alone. Serendipodous 17:37, 10 December 2014 (UTC)
There are lots of problems with that image (axis labels too small, colors too washed out, etc.) I could play around with it if you're keen (tomorrow, perhaps). Some idea of what you're looking for might help. WilyD 17:47, 10 December 2014 (UTC)

[outdent]Well, I like the wider spread that makes things clearer; perhaps labels on the largest objects? A black background would be best, maybe? Serendipodous 18:59, 10 December 2014 (UTC)

Well, i dunno how I feel about the labels.
I dunno aboot the labels, eh?

Well, I'll leave that up to you. :) Looks nice though! :)Serendipodous 11:52, 11 December 2014 (UTC)

Well, Pluto and Eris work okay? I suppose. But the other two are too small? Personally, I find it a bit confusing to have the labels hanging loose outside the symbols, but perhaps people think I'm nuts? WilyD 11:56, 11 December 2014 (UTC)
Makemake kinda works too. I think you could get away with just moving 2Haumea" above the circle. Serendipodous 12:02, 11 December 2014 (UTC)
Well, if you'd rather, I can leave the labels, but inconsistent placement ain't good. WilyD 12:31, 11 December 2014 (UTC)
Fair enough. Serendipodous 16:24, 11 December 2014 (UTC)
Well, if you don't want any changes to those, I'll think about the main image (but that'll take longer). WilyD 18:04, 11 December 2014 (UTC)
Not as hard as I'd thought; I used to be a lot shittier at this sort of thing, I guess. Anyways, the minor planet centre no longer separates out centaurs and scattered disk objects (which is good in that separating the scattered disk from the hot classicals is dumb, but is bad in that including centaurs here is not good). Also, I plotted all the planets (including Pluto!), so everyone less than two earth masses should probably be cut. Orange is probably the wrong colour for planets (looks too much like the solar yellow?) Doesn't stand out that well against grey (also a bad choice?) What to do about centaurs? plot everyone with a < 30 in a different colour? Other points? WilyD 14:44, 12 December 2014 (UTC)
Pluto shouldn't be presented as a planet, for it is not one. It is simply the largest Kuiper belt object. --JorisvS (talk) 15:23, 12 December 2014 (UTC)
Well, unless you don't count resonant objects as Kuiper belt objects (which you shouldn't!). But it's just because I used the default MERCURY planet input. WilyD 15:29, 12 December 2014 (UTC)
Okay, better colours (I thought - brightness looks a lot lousier as a thumb), cut extraneous planets, cut centaurs (though Scattered Disk Objects are still included, as the Minor Planet Centre no longer pretends you can meaningfully distinguish between SDOs and Hot Classical objects). Probably, at least, the colour of the KBOs needs to be brighter? Previous plot had Neptune Trojans, Centaurs, and Jupiter Trojans; are those still desirable? Were they ever? WilyD 15:52, 12 December 2014 (UTC)
Nevermind the colour complaint, I think it's good now. WilyD 15:55, 12 December 2014 (UTC)
Looks good now. If we want a plot without centaurs, we could also have a separate one; I think the one with them is also informative. Depending on which resonance (and therefore semi-major axis), resonant objects are either considered KBOs or SDOs, though never classicals. --JorisvS (talk) 16:29, 12 December 2014 (UTC)
Well, I can make a second with centaurs on ... Tuesday, maybe. Not before. Perhaps with and without trojans (though main belt/near Earth asteroids are certainly out - not resolvable). If there's any authoritative source of resonant objects (or at least a citable one), they can be marked out, but I don't think there is. Classicals aren't really a thing to intelligently use, though, since Hot Classicals and Cold Classicals don't form a clade. But since the literature is a hopeless mess, we're hosed here. WilyD 17:07, 12 December 2014 (UTC)
You could pick the cut-off inclination (which seems 12° per classical Kuiper belt object) and maybe give them different colors or something. I can't think of an easy way to weed out the resonant KBOs, though. --JorisvS (talk) 17:38, 12 December 2014 (UTC)
Well, different people use different standards, and for obvious reasons - the hot and cold populations of the Kuiper belt overlap. Since there's ~0 agreement in the literature as to how to subdivide TNOs, we're not particularly obliged to reproduce something we know to be wrong. Doing some resonant objects ain't hard; but the published lists are woefully incomplete. But I'll think about highlighting objects named as 3:2 (and perhaps others?) in the literature. WilyD 09:56, 15 December 2014 (UTC)
True. It'll probably take relatively in-depth study of a KBO to know whether it is really part of the hot or the cold population and even then it could be difficult to decide in some cases. --JorisvS (talk) 11:59, 15 December 2014 (UTC)
+= Centaurs (Green), Neptune Trojans (Fuchsia?), and Uranian Trojan (Yellow-y).
Are Jupiter Trojans a good idea? They were on the old one, though I can't recall why I'd do that. WilyD 10:56, 15 December 2014 (UTC)
Wouldn't that just create blobs in the plot in front of and behind Jupiter? I'd have to see it to be able to properly judge that. --JorisvS (talk) 11:59, 15 December 2014 (UTC)
Yes, orange-y blobs
Well, one starts to run out of colours, especially if they're colour-blind. Jupiter Trojans are much more akin to asteroids to my mind than to TNOs. WilyD 12:13, 15 December 2014 (UTC)
Like KBOs, Jupiter trojans are often icy, and they may well have originated in the proto–Kuiper belt. During planetary migration (when Jupiter and Saturn went into 1:2 resonance, which would have destabilized any pre-existing Jupiter trojans) the ice giants plunged into the proto–Kuiper belt, sending many PKBOs inwards, some of which were then captured in Jupiter's Lagrangian points. I don't mind the orange blobs and they do make it clear that that area of space contains many known objects. --JorisvS (talk) 12:54, 15 December 2014 (UTC)
Well, asteroids are often icy too. While there's obviously some mixing, it's clear that all "small bodies in the outer solar system will all come from the same parent population" predictions of the Nice Model were wrong (although differing percentages of a few parent populations is still allowed) - I don't think . Frankly, it was always kinda silly, given that Hal was like the first guy to realise the high inclination and low inclination bodies have different size distributions. Although for the purposes of the plot, I suppose it hardly matters; we're stuck with the current imperfection state of information + a confused literature and being a secondary source. WilyD 13:43, 15 December 2014 (UTC)
There has indeed been a lot of mixing, e.g. Ceres has been hypothesized to have originated in the Kuiper belt. Moreover, it is silly to pretend that the entire proto–Kuiper belt was compositionally homogenous in the first place. Because of the extreme difficulty in determining origins, current characteristics are often preferred in classifications. --JorisvS (talk) 13:50, 15 December 2014 (UTC)
Well, with sufficient mixing, the resulting populations would've been homogenous. Origins are difficult to determine, but other classification schemes run into the problem that if you don't do it by origin, you either can't deal with the overlap, or use hard cuts that look artificial for our purposes. In any event, most objects aren't well enough characterised to hope to much meaningful anyways, though I could highlight objects that have been identified as resonant objects (which're overrepresented anyways, since they're overrepresented among low q objects). WilyD 18:28, 15 December 2014 (UTC)

I'm surprised; there are a lot more blue dots interior to the Kuiper belt than I expected. Serendipodous 13:33, 15 December 2014 (UTC)

Previously SDOs were binned with Centaurs; but the MPC stopped distinguishing, so now they're binned with KBOs. WilyD 13:47, 15 December 2014 (UTC)
To check, the blue ones are TNOs with perihelia inside Neptune's orbit, right? --JorisvS (talk) 13:50, 15 December 2014 (UTC)
Blue ones are "distant objects" from the Minor Planet Centres list of distant objects, less objects with a < 30.05, which the Minor Planet Centre defines to be Centaurs. I'll have to dig around for what they mean by distant objects, but I think it's q > 5.2 au; So yes, the ones Serendipodous is talking about are a mix of Resonant and Scatted objects with q < 30.05 au). WilyD 18:28, 15 December 2014 (UTC)

Ah bugger! Does this mean that the MPC has changed its trans-Neptunian definition? That means we have to too! Serendipodous 18:50, 15 December 2014 (UTC)

Perhaps not - I was using their list here, although they do still seem to maintain separate centaurs + SDOs list and resonant + hot classicals + cold classicals but not any 5:2 or longer period resonants list. Like everything, jumbled mess. WilyD 22:35, 15 December 2014 (UTC)
Now with separate SDOs and Centaurs (@a=30.05)
Right, so I re-did it, separating Centaurs, SDOs, and "Kuiper Belt Objects", where "Kuiper belt objects" means a > 30.05, a < 50, and whatever eccentricity cut the MPC randomly chose. Note that this means resonant objects with a > 50 (such as 2000 FE8) are plotted as "Scattered Disk Objects", while those with a < 50 (Such as 1995 HM5) are plotted as Kuiper belt objects. Which ain't great. WilyD 10:42, 16 December 2014 (UTC)
Maybe we could also have the two sednoids in a distinct color? --JorisvS (talk) 10:46, 16 December 2014 (UTC)
The current best plot
I'm not sure we really want to encourage that kind of silliness (especially since everyone will have their own definition for "extended-detached" or whatnot). Since this is about the Kuiper belt, presumably that's the structure we want to show. I plotted the objects I could find sources called resonant as resonant (Which is Gladman et al. 2008, Petit et al. 2011, plus one from Sheppard et al. 2012 - if anyone's aware of recent sources, please do), and dialled down the brightness of everything but Classicals and Resonants. Drives me batty treating Hot Classicals and SDOs differently, but what can you do? Some way of separating Cold Classicals might be a good idea; I'll dig for someone I can blame for the choice. WilyD 14:36, 16 December 2014 (UTC)
Oh, and Alexandersen et al. 2014 WilyD 15:33, 16 December 2014 (UTC)
Alright, unless there's anything else, I suppose File:Plotoftheoutersolarsystemwithresonantobjectsandwhaticanonlyassumeareturtles.png and File:Whaticanonlyassumeisapornographicmovie.gif are what's wanted/needed. Since the plot's also used at Centaur (minor planet), I suppose I should make another version in which centaurs are brighter and classicals/kbos dimmer. Which I'll do unless anyone wants more changes? WilyD 09:50, 17 December 2014 (UTC)
Thanks! I was actually going to suggest that Centaur idea. Serendipodous 12:01, 17 December 2014 (UTC)
Yeah, no worries. Since it's all scripted now, making new plots is not terribly hard, if other variations are needed/wanted. WilyD 13:42, 17 December 2014 (UTC)

There may be only two known sednoids, they orbital parameters are distinctly different from those of the normal detached objects. It may be over the top for a plot focused on the Kuiper belt, but it may be interesting for a general plot of trans-Neptunian objects. --JorisvS (talk) 13:18, 17 December 2014 (UTC)

That's not remotely true. For instance, the de la Fuente Marcos paper shows how smoothly they blend into other extended objects (which themselves blend smoothly into hot classical and regular scattered). We could highlight every arbitrary division people have thrown around over the years, but the plot would be way too busy (which it already is). Even the articles here (which get a bit of press release hype into them) call Sednoids Detached objects (and detached notes everyone makes a different definition, because they joint smoothly with regular scattered). WilyD
Not quite. That paper discusses that the argument of perihelion is close to 0° for all minor planets with a>150 AU and q>30 AU, which is not only the detached objects and sednoids. It does mention Sedna and 2007 TG422 (the latter is just a scattered-disc object) as outliers in semi-major axis. But the sednoids are outliers, too: the perihelia of Sedna and 2012 VP113 are far larger than those of any of the detached ones (the next one is 2010 GB174 at 48.6 AU), and yet that article does not mention this as such. --JorisvS (talk) 16:40, 17 December 2014 (UTC)
Nominally different, but we're restricted in total number of colours that're legible (and already pushing that limit, I think; though again, being colourblind may influence that). The dynamical difference between a pericentre of 50 and 75 au in the solar system is neglible - (and heck, even the name appears to be just the title of Scott Sheppard's page on it - doesn't appear in the literature, and I've never heard it in the field. There are several more important divisions we're glossing over here. WilyD 18:16, 17 December 2014 (UTC)
The red part of the spectrum looks underused. Even using the red of the planets would be unproblematic. The difference is that normal detached objects could have been produced during an eccentric-Neptune phase during planetary migration, whereas this is impossible for the sednoids, which, for that reason, have also been called inner Oort cloud objects. I don't care too much about it, though. --JorisvS (talk) 18:55, 17 December 2014 (UTC)
I'm really not okay with re-using the planetary red, but a dark red or an orange-y red might be okay. Though, again, if we're going to add colour, we should use important, common divisions with the Kuiper belt (Cold Classical vs. Hot Classical, or Inner-Main-Outer, or Plutinos/Twotinos/Other Res), not push an unused classification. When the lit figures out if they're Hill Cloud objects (assuming such a thing exists), or if their pericentres were raised by a Lykawka-Mukai object, or whatever (Did Levison ever publish his work on collisional inject to make detached objects?), we might revisit it, but we shouldn't be using a relatively main article to push a somewhat fringe-y theory (especially using a term that basically exists only in the minds of Wikipedians). WilyD 10:50, 18 December 2014 (UTC)

I added resonant identifications from a few places. I'm strongly tempted to add updated orbital elements for the objects listed here: if the MPC data doesn't have 2+ Oppositions, because a lot of those are scary-bad. WilyD 16:28, 17 December 2014 (UTC)

Upon investigation, so are a lot of the CFEPS ones, but I think they're less misleadingly bad, and more just plain bad. Anyways, I do plan to upload a new one once I've poached all the CFEPS values & resonant identifications, as well as one where the centaurs/scattered objects are bright and the classical/resonant objects dim. Anything else, is mostly easy, so feel free to ask (though, uh, the movie is still a little manual, so it's a smidge of work. Everything else is pretty trivial.) WilyD 10:38, 22 December 2014 (UTC)

Anyways, I notice Serendipodous (talk · contribs) put the movie file into the article, but given that it doesn't give any indication it's a movie, shouldn't the static one be used? Or an indication you can watch it be added?

Static one's fine by me, if you'd prefer it. Serendipodous 11:53, 22 December 2014 (UTC)
If there's some reason you used the movie file by all means do, but I couldn't guess why you did that. I suppose it doesn't really matter, but doing so shows the first frame of the movie (which is January 1st, 2000 positions) rather than the static (which uses December 1, 2014 positions). WilyD 12:04, 22 December 2014 (UTC)

I mostly automated the movie-makery, so I can easily fudge those around or make other variants, if people ask. WilyD 14:38, 24 December 2014 (UTC)

About the lead image - suggestions[edit]

Known objects in the Kuiper belt beyond the orbit of Neptune (data from the Minor Planet Center).

      Kuiper belt
      Scattered disc

      Jupiter Trojans
      Giant planets
      Neptune trojan

Known objects in the Kuiper belt, derived from data from the Minor Planet Center. Objects in the main belt are colored blue, whereas scattered objects are dark green. The four outer planets are red. Neptune's few known trojans are purple, whereas Jupiter's are grey. The scattered objects between Jupiter's orbit and the Kuiper belt are known as centaurs. The scale is in astronomical units. The pronounced gap at the bottom is due to difficulties in detection against the background of the plane of the Milky Way.
Outersolarsystem objectpositions labels comp.png
Known objects in the Kuiper belt beyond the orbit of Neptune

      Kuiper belt
      Scattered disc (outer region)

      Jupiter Trojans
      Giant planets
      Centaurs (inner region)

(data from the Minor Planet Center)

There has been a lot of talk about the lead image recently.


Here are two alternative versions (left) compared to the current version (right).


With all due respect to the effort previously invested, but the current lead image seems not very instructive to the general reader. I'd rather see it replaced by one of the alternatives. Since I don't want to complicate things too much I post them here and leave the article unchanged. Cheers, -- Rfassbind -talk 18:18, 25 January 2015 (UTC)

If I read this right, this is just the same plot but with the outermost objects cropped off. WilyD 11:11, 26 January 2015 (UTC)
The image on the top left is only slightly better Tetra quark (talk) 11:58, 26 January 2015 (UTC)
In any event "this is better" without any indication of why one thinks it's better is not very helpful. WilyD 12:34, 26 January 2015 (UTC)
Hi WilyD, what's your opinion? As you surely have noticed the differences are not just limited to cropping your image. BR, -- Rfassbind -talk 15:07, 26 January 2015 (UTC)
As far as I see, they're just crops. Are the brightnesses fiddled with or something? Since there are no KBOs beyond 60 au, I suppose plotting all the scattered disk objects ain't necessary, since we treated SDOs as not KBOs for weird historical reasons that I won't rant much about. Normally I wouldn't be caught dead making a plot without axes. WilyD 15:26, 26 January 2015 (UTC)
My first suggestion uses the same image currently used in the article, i.e. the version you uploaded on Dec 23, 2014 to wikipedia. Yes, scales and units are understandably a must-have for a professional, but since it is a WP:LEADIMAGE that accompanies the lead and also features a text in the caption, the lack of any plotted axis might be generously overlooked, I hope. BR, -- Rfassbind -talk 15:51, 26 January 2015 (UTC)
Yes, I see that it's the same image (and the other one is a crop o' the image I made a'for). I mean, I'll make whatever image, but if it's just a crop that's wanted, or a brightness complaint, or that making it big enough to include the Scattered Disk is unnecessary (but keep the axes), or ? is necessary to understand to do it. I try not to care, because I get irritated with all the errors that come out of the literature into the article, so I'm happy enough to do whatever. WilyD 16:03, 26 January 2015 (UTC)
It's because it is more zoomed in, showing only what interests. The legend is not a plus because it could be on the current image as well Tetra quark (talk) 16:09, 26 January 2015 (UTC)
Yes, exactly (if I may reply without being addressed) the image is not only cropped, it is also enlarged as if the original were 500px wide. As for the legend, there are certainly many other possible alternatives. However, the current version doesn't have a legend, my suggestion does, so I consider that an improvement. Don't you? Cheers, -- Rfassbind -talk 16:51, 26 January 2015 (UTC)

──────────────────────────────────────────────────────────────────────────────────────────────────── WilyD, it would be fabulous, if you can prepare a different version, that doesn't need the cropping. That would make things simpler and therefore better. Here's my suggestion (I'm trying to be as specific as possible and not to be regarded as being demanding)

  • Image: cutoff at 55 AU as in the cropped version
  • No AU scale
  • No legend in the image, as a concentric circle in a square does not give a lot of options
  • Slightly enlarge size of objects. Even if it's only +1 pixel it should be notable.
  • Lighten up color: KBOs from currently #0088CC (RBG 0.136.204) to #1AB3FF (RGB 26.179.255)
  • Planets: instead of labels "Jupiter", "Saturn", "Uranus" and "Neptune" → only J, S, U and N in twice as large, bold letters.
  • No label for the Sun, as the yellow dot in the middle needs no explanation other than in the caption's legend.
  • Lighten up the Neptune trojans (if mentioned in the legend). Currently RGB 102.0.102 or #660066. Change to RGB 255.51.255 or #FF33FF.
  • Upload the final version to wikicommons instead locally on wikipedia and add legend to description page in French, German, Spanish and Portuguese, so that the image can be used in these articles (I could take care of that topic, although Tetra Quark probably knows better most of these languages).
  • Displayed image width in the article would be 330px. The caption will feature a legend. The caption's text could be expanded and linking to "Classical KBOs", "Resonant KBOs" and "Plutinos", I think.

That's it. It would be an honor to participate in your efforts. Cheers, -- Rfassbind -talk 18:02, 26 January 2015 (UTC)

Known objects in the Kuiper belt beyond the orbit of Neptune (scale in AU).
      Jupiter Trojans
      Giant planets (J · S · U · N)
      Kuiper belt
      Scattered disc
      Neptune trojan
  • I lightened everything, but kept the Neptune trojans pretty dark, in line with the Uranian Trojan, Jupiter Trojans, Centaurs, and SDOs, which are also not KBOs (per Wikipediar, anyhew)
  • I kept the au scale, because removing it gave me the heebee-jeebees, but moved it so it wasn't wasting space
  • The cutoff is at 60 au, because the most distant thing being called a KBO is at 58.something au
  • I had nothing to do with the caption, which ain't part o' the image anyhow.
  • Si nous serons en d'accord d'une image finale, on peut uploader l'image au Wikimedia Commons, mais pour example images il faut les uploader ici, parce que c'est pas vaut the hassle, non? Aussi, je ne peut pas écrice des captions in German, Espagne, Portugeuse or des autre langues. So we'll just stick with the horse for le moment, eh? WilyD 10:33, 27 January 2015 (UTC)
Known objects in the Kuiper belt, derived from data from the Minor Planet Center. Objects in the main belt are colored blue, whereas scattered objects are dark green. The four outer planets are red. Neptune's few known trojans are purple, whereas Jupiter's are grey. The scattered objects between Jupiter's orbit and the Kuiper belt are known as centaurs. The scale is in astronomical units . The pronounced gap at the bottom is due to difficulties in detection against the background of the plane of the Milky Way.

Wow, that was fast and well done! I also think you did the right thing by keeping and amended scale and cutoff at 60 AU. I added a revised legend to your new image and reposted the original lead-image (left) again for comparison. Yes, let's do the wikicommon upload and international articles later, after we finished here. Also good to know that French won't be an issue ;)

Now, if anyone has additional suggestions, pls do so. Otherwise I'd like to address the caption, which I consider a vital part of the lead image. By using a legend some text in the original caption has become obsolete (strikethrough text). Good captions are short captions and mentioning (one of several) artifacts like in the end of the original caption is distracting to the general reader (especially when presenting a link to the Milky Way). Also the Minor Planet Center is best mentioned as a source after the legend. Questions:

Last thought: Maybe this is corny, but most general readers will come into contact with the Kuiper Belt article because of dwarf planet Pluto. What about indicating the position of Pluto by drawing a circle around it? I think it would be very intuitive for the general reader as he or she can easily relate to.

Once again, well done image. Cheers, -- Rfassbind -talk 16:12, 27 January 2015 (UTC)

Well, I have a script, so if it's just re-plotting the same data in a slightly different fashion, it ain't hard. Note that the orbital elements are from MPC for multi-opposition objects, but CFEPS for single opposition objects, plus CFEPS & a bunch of other sources (listed in the desc.) are used to identify resonant objects. WilyD 17:48, 27 January 2015 (UTC)
OK, very well Wily. I'll post this provisional version on the article's lead and hope to get some feedback to the open questions. Would it be correct to use a date in the caption, for example, "Known objects in the Kuiper belt [...] as of 2015"? -- Rfassbind -talk 02:50, 28 January 2015 (UTC)
Yeah, something like "Known Kuiper belt objects (or object positions?) as of 1st January 2015" would be correct, and gloss over unnecessary details, I think (which're on the image desc. page, for the truly curious). WilyD 09:27, 28 January 2015 (UTC)
I just uploaded the most recent image to wikimedia commons under your authorship and given license. See: w:File:Kuiper belt plot objects of outer solar system.png. Did I get most of it right? Cheers, Rfassbind -talk 13:54, 29 January 2015 (UTC)
Caption there should probably include colours for resonance objects, Uranian Trojan, Centaurs, even if it's not necessarily necessary here. WilyD 14:16, 29 January 2015 (UTC)