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)