Talk:Kuiper belt

Pronunciation of Kuiper

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". Serendi^podous 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. -RadicalOne•^{Contact Me}•_{Chase 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 http://en.wikipedia.org/wiki/Talk:Kuiper_belt, but the only discussion I see regarding the pronunciation of Kuiper is http://en.wikipedia.org/wiki/Talk:Kuiper_belt#Pronunciation_of_Kuiper, 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 http://en.wikipedia.org/wiki/Dutch_language#Vowels. [œy] being not a native vowel in English may have caused this confusion. —Preceding unsigned comment added by Upquark2 (talk • contribs) 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." Serendi^podous 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." Serendi^podous 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. Serendi^podous 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"Serendi^podous 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". Serendi^podous 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. – Kerαunoςcopia^◁_galaxies 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)

From a South African English point of view Afrikaans /ui/ is perceived to be the rounded form of /ei/ or /y/ and therefore if speaking English and not trying to exactly match the Afrikaans pronunciation (as the /ui/ sound is not native in English) that is what it would be pronounced like. Kuiper would be pronounced as "caper" (the little green pickled thing). Now I'm not sure if Dutch /ui/ is pronounced the same as Afrikaans, but I suspect it is.

At school we were always taught to pronounce the sound in this way; if trying to say "Kuiper", say English "caper" but keeping the tongue firmly on the bottom of the mouth for the "A" sound, with lips rounded and slightly pouted as if to to kiss someone! — Preceding unsigned comment added by 77.102.254.132 (talk) 12:50, 13 July 2015 (UTC)

As a native Dutch speaker living in the Netherlands, I just wanted to say I think this is the best description I have ever seen, of how to pronounce the "ui" sound in Dutch. I had to try it to believe it, and yes, I think you nailed it. ;) As Dutch people we are aware how tricky our "double vowels" (au/ou, oe, eu, ui, ei/ij) are to pronounce for foreigners, and frankly, a lot of Dutch people do a sloppy job themselves on a daily basis. Especially "ui" "eu" and "ei/ij" may be tricky to learn, and tricky to distinguish between them. They are different though, and "ui" is also different from the "y" (like in "hyper"). They may sound so simmilar to a non-native Dutch speaker, that people may THINK they are hearing "y" even in an audio clip demonstrating the pronunciation (as evidenced by a few reactions here in this discussion), while a native Dutch speaker will say, no that's clearly an "ui" you are hearing. Greetings, RagingR2 (talk) 12:03, 4 February 2016 (UTC)

Origins

Some notes on origins and the Nice model

The instability has many variations, in those examined in the 2008 paper Neptune is scattered outward into a high eccentricity orbit which is then damped by dynamical friction and migrates out toward its current orbit. While Neptune's orbit is eccentric its mean motion resonances overlap and orbits in the region between its 3/2 and 2/1 resonance are chaotic, during this phase low inclination objects are shifted outward forming the cold belt. Later as Neptune is migrating outward the hot belt forms as some of the scattered objects are decoupled from Neptune through secular and mean motion resonances. In addition to the eccentricities in this variation not matching observation, the loosely bound binaries in the cold belt would be split if they encountered Neptune leading to suggestions that the cold disk formed in place, and the hot belt doesn't include enough higher inclination objects.

There were some later (rather technical) papers that examined what orbits Neptune could have which preserved a cold belt while populating a hot belt, these used lower eccentricities than the 2008 paper. And another that looked for ways of leaving the outer part of the cold belt with higher eccentricities.

Then there is the five planet version where in some cases Neptune migrates outward several AU before the planetary encounters begin. The hot belt is created in much of the same manner as in the 2008 paper, except part of this occurs before the planetary encounters, and the inclination distribution can be matched with the right combination of timescale and migration distance, Objects captured in the 2/1 resonance during the first part of Neptune's migration are left behind as a local concentration at 44 AU in the cold belt when Neptune semi-major axis jumps outward as it encounters the extra planet sometime before that is ejected. Later the eccentricity distribution of the cold belt can be truncated by slow resonance sweeping.

I'm thinking of adding, well seeing how long it turned out, some of this to the origin section. Probably the point about the cold belt being formed at its current locations because of the loose binaries, the inclination distribution mismatch in the 2008 paper, and something about the five planet version.

But, this having been rated a feature article, I would like other opinions first.Agmartin (talk) 18:24, 1 February 2016 (UTC)

I think this would be good material to add. This article is somewhat dated and in need of refresh to be brought up to speed. -- Kheider (talk) 20:26, 1 February 2016 (UTC)

Same here. Serendi^podous 12:28, 13 February 2016 (UTC)

I've rewritten parts and added some new material from a recent five planet version of the Nice model with some comparison between the two versions.

@Agmartin:, just going through your additions to the article (great addition on the whole) and am unclear as to the definition of the "hot disk"; I'm assuming that is the same as the dynamically hot classical Kuiper belt, but am not certain. Serendi^podous 16:27, 27 February 2016 (UTC)

That's what I meant, I was trying to abbreviate since my additions were getting rather long. Given that the current division between the hot classical belt and the scattered disk at a semi-major axis of 50 AU appears arbitrary, I think it could also be used to refer to both, though using it that way may need to await a paper that specifically spells out that they formed via the same process. Agmartin (talk) 17:47, 27 February 2016 (UTC)

Perhaps using hot belt instead might have have been better. Agmartin (talk) 17:51, 27 February 2016 (UTC)

I've done some changings. Serendi^podous 18:04, 27 February 2016 (UTC)

Good idea about relocating sections. I switched the 'recent modifications' link to Hypothetical fifth giant planet. I've been pondering moving that article to five-planet Nice model since that is what it is describing. What do you think? Agmartin (talk) 19:46, 27 February 2016 (UTC)

Oort Cloud a thousand times more distant? I think not...

The article reads "The Kuiper belt should not be confused with the theorized Oort cloud, which is a thousand times more distant..." That depends on how you look at it...

Kuiper Belt: from 30 to 50 AU from the Sun. Oort Cloud: beginning at somewhere between 2000 and 5000 AU, and ending somewhere between 50.000 and 200.000 AU. (Note that the outer limit carries the greatest level of uncertainty.)

So depending on these numbers, you could say:

• the beginning of the Oort Cloud is somewhere between 67 and 167 times as distant as the beginning of the Kuiper Belt
• the center of the Oort Cloud is somewhere between 26.000 and 102.500 AU, so that's somwehere between 650 and 2562.5 times as distant as the center of the Kuiper Belt.
• the outer limit of the Oort Cloud is somewhere between 1000 and 4000 times as distant as the outer limiet of the Kuiper Belt.

As you can see, these numbers vary greatly, and it depends strongly on which way you look at it, which number is the most appropriate. Personally, I feel when describing how distant something is, it makes more sense to talk about where it begins, or MAYBE where the center is, but not where it ends. You don't say "Europe is XXXX kilometers away", and then refer to the geographical center of Europe or where Europe ends. No, you will refer to whatever European border you will reach first from your location. You don't say "that group of people is standing XXX meters away from me", and then refer to where the center of the group is. No, you will measure it according to where the first people from your position are standing. In any case: these numbers are also based on data (for the Oort Cloud specifically) that is still pretty uncertain.

So all things considered I think it's at the very least a false suggestion of accuracy, and in the worst case an exaggeration to say that the Oort Cloud is 1000 times as distant as the Kuiper Belt. I think a more appropriate description would be "2 or 3 orders of magnitude more distant". That way you leave it open whether it's in the 100's or in the 1000's; which is appropriate since the specific details of the Oort Cloud still carry a great level of uncertainty.

(P.S. And even then it's pretty generous, because if the Oort Cloud indeed will prove to begin at 2000 AU, then the beginning is "only" 67 times as distant as the Kuiper Belt's beginning, so that's not even in the 100's.)

Greetings, RagingR2 (talk) 00:35, 5 February 2016 (UTC)

Composition

Looking at the citations in this section it doesn't appear to have been updated recently. I have found this review article from 2012 discussing the composition and the surfaces of the Kuiper belt objects. The Compositions of Kuiper Belt Objects And this more recent paper Agmartin (talk) 22:26, 1 March 2016 (UTC)

Some things from the first source that could be added to this section.

The binary objects with known masses determined from their orbits and diameters determined by measuring albedo using thermal emissions have a variety of densities. Some small objects have densities significantly below that of ice indicating that they are very porous and contains little rock. The largest objects are more dense indicating that they contain a significant fraction of rock. The varying densities may be due to the locations where they formed with the mix of materials varying with distance from the sun, or be due to loss of ice when objects merged to form the largest bodies.

The albedos of the moderate to large objects increase with diameter.

The spectra of the largest bodies indicate the presence of methane, in some cases dissolved in nitrogen, carbon monoxide is also expected to be present. Their presence on the surface of only the largest objects may be due to their retaining a thin atmosphere. The methane in processed by radiation into ethane and heavier hydrocarbons causing surfaces to darken and redden. Crystalline ice has been detected on surfaces of moderate to large objects, this may be due to cryovolcanism aided by the depression of the melting point of water due the ammonia.

The colors of smaller objects are either dark and neutral or brighter and very red. Binaries have similar colors indicating that both components formed in similar locations or that they binaries formed in their original collapse. One hypothesis for the differing colors is that the red objects formed far enough from the sun to retain methanol. The cold classicals are all red, other dynamical classes contain a mix of colors. Agmartin (talk) 22:45, 3 March 2016 (UTC)

I'll get going on this soon. Serendi^podous 22:52, 3 March 2016 (UTC)

Histogram

I've replaced the histogram with an up to date one split by inclinations above and below 5 degrees. That file didn't include Neptune trojans. The link to the file with those included is here

Histogram of Kuiper belt objects with inclinations above and below five degrees. Includes Neptune trojans.

(click on edit to see the link) if that is the preferred version. Agmartin (talk) 21:54, 4 May 2016 (UTC)

What is the "kernel"? I don't think that's defined in the text. Serendi^podous 21:35, 4 May 2016 (UTC)

I mentioned a concentration of objects left behind when Neptune jumped outward in the origin section. I hadn't noticed that it wasn't discussed previously. I guess I'll need to add that. Agmartin (talk) 21:54, 4 May 2016 (UTC)

size distribution

I believe the illustration and text related to the size distribution power law are wrong. If N represents the number of objects with diameters greater than D then if q=4 the number of objects of diameter 2D should be 1/16 of those of diameter D. The total number of objects larger than 2D should be 1/8 of those larger than D. If I'm misunderstanding would someone point out what I'm missing. Agmartin (talk) 20:25, 11 August 2016 (UTC)

• In the usual usage, dn/ds ∝ s^-q, which you have to integrate to get the total number larger than that size. To talk about how many objects are of size D, technically, you need to specific a size range over which you're talking about. In any event, that whole section needs to be totally redone, because it started as outdated whatnot, and updates have been tacked on here and there without any real organisation. Kepler47 (talk) 17:03, 8 December 2016 (UTC)

Unnecessary(?) information on mass

In the main section, the Kuiper belt is said to be "20 to 200 times as massive." as the asteroid belt. This doesn't seem to be helpful because it is so vague and uncertain. Should it be removed?

PS: Is there a certain name for the main section of the article? I don't know what to call it. — Preceding unsigned comment added by 50.5.96.209 (talk) 23:25, 7 May 2017 (UTC)

Unsatisfactory exploration section

This is an interesting article, but the exploration section is unclear and dated, and well below the standard for a TFA. 1. "Scientists awaited data from the Pan-STARRS survey project to ensure as wide a field of options as possible." "field of options" for what? From the next paragraph, it is clear that it is the next target for New Horizons after Pluto, but the reader should not have to wait until then to understand. 2. The Pan-STARRS project to find a suitable target is presumably now finished since a target has been chosen, but the comments still assume that the project is at an early stage. 3. "it was revealed that Hubble's search had uncovered three potential targets" In the previous paragraph it was implied that the search was being conducted by earth based telescopes. 4. The article states that it will be announced in August or September 2016 whether funding is available for the target beyond Pluto. Presumably the result was favourable, and the article should cover this. 5 New Horizons is not mentioned until the exploration section, and the article has not been updated to take account of what has been learned from the mission. Dudley Miles (talk) 21:28, 14 May 2017 (UTC)

I've revised most of your concerns; as for how the New Horizons mission changed our understanding of the Kuiper belt, well, it hasn't yet- we know a lot more about Pluto, but Pluto is not a typical member of the Kuiper belt. The next KBO encounter is more likely to provide this page with new information. Even so, it's like trying to learn about a beach by looking at grains of sand. Serendi^podous 06:48, 15 May 2017 (UTC)

Thanks. The section is greatly improved, although I think there is still far too much detail on how the new target was chosen for a general article on the Kuiper Belt. I do not, however, agree with your comment about Pluto. It is mentioned 54 times in the article and has its own sub-section. I think there should be a brief summary of the discoveries, together with your comment that the general increase in knowledge about the KB is limited because Pluto is atypical and we should learn more from the next encounter. The article on Planet Nine says that it may perturb the orbits of outer KBOs, and I think this should also be covered. Dudley Miles (talk) 07:34, 15 May 2017 (UTC)

Planet Nine is creeping everywhere at the moment. Let's corral the thing until we actually find it. Pluto's importance is more cultural and historical than scientific; specific discoveries about Pluto tell us little about the Kuiper belt in general. We'd need a few more missions to a few more large objects before we could draw any conclusions. Serendi^podous 07:46, 15 May 2017 (UTC)

"As for how the New Horizons mission changed our understanding of the Kuiper belt, well, it hasn't yet" - I wouldn't say that. New Horizons already provided a large number of results about the Kuiper Belt, from crater statistics on Pluto and Charon to the physical properties and orbital dynamics of 1994 JR1. It has observed all other distant dwarf planets (Makemake, Haumea and Eris) studying their surface properties. Results for that are expected to be published within the next months.Renerpho (talk) 04:16, 21 May 2017 (UTC)

The crater count info might be worth including, if I could make head or tail of it. The paper seems to be suggesting there should be a large amount of small craters, but then admits there aren't. Serendi^podous 12:29, 21 May 2017 (UTC)

They are comparing the crater counts from New Horizons with those expected using a model (the Schlicting paper they cite) where the kuiper belt objects started as ~km sized bodies that underwent runaway growth. The model predicts a large number of small bodies (and thus small craters) observations show few small craters leading to speculation that the kuiper belt objects formed as larger objects. It is mentioned briefly in the origin section.Agmartin (talk) 19:32, 21 May 2017 (UTC)

Some recently published New Horizons results Icarus special issue unfortunately most are pay-walled.Agmartin (talk) 19:34, 21 May 2017 (UTC)

And a few articles from last year at Science good summaries were in research March 18, 2016 free access if you register.

Most of this material would be better placed in the Pluto or New Horizons articles, however.Agmartin (talk) 19:43, 21 May 2017 (UTC)

Dubious

The Kuiper belt extent may be out of date. Dr Alan Stern states Kuiper belt extends to approximately 70 AU New Horizons Press Briefing: Science Results & First Clear Photos from Ultima Thule, not 50 AU. The greater extent is based upon recent OSSOS survey data OSSOS: X. How to Use a Survey Simulator: Statistical Testing of Dynamical Models Against the Real Kuiper Belt — Preceding unsigned comment added by Ehb54x (talk • contribs) 19:35, 3 January 2019 (UTC)

These numbers refer to two different things. The extend of the Kuiper belt mentioned in the article refers to the semi-major axis a (an object's average distance from the Sun). There is a sudden drop in the number of objects after a=50 AU, the so-called Kuiper cliff. Because of the moderate eccentricity of the orbits, the drop is less pronounced when you go by the distance from the Sun, which is what Alan Stern was referring to. What matters for spacecraft exploration is the actual distance of an object from the Sun, not its average distance. You still find plenty of objects out to 70 AU. Renerpho (talk) 05:27, 6 January 2019 (UTC)

Definition improvement

Can we be explicit in the definition that the star alluded to in the definition wrt "circumstellar disc" is, in fact, the Sun? This is of course obvious to those with some knowledge of the topic, but the WP:LEAD and especially the definition should really not assume that.

The first sentence currently reads:

The Kuiper belt (/ˈkaɪpər/), occasionally called the Edgeworth–Kuiper belt, is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune (at 30 AU) to approximately 50 AU from the Sun.

Instead, I'd like to see the predicate reworked thus:

...is a circumstellar disc centered on the Sun in the outer Solar System, extending from the orbit of Neptune (at 30 AU) to approximately 50 AU from the Sun.

Afaic, the first definition is completely compatible with a small brown dwarf orbiting arond the Sun at about 40 AU, with a 10 AU belt around it. Let's not require that schoolchildren reading the article have some prior knowledge of the Solar System in order to make sense of the first sentence. I actually like the definition at Simple English wiki, and we could do worse than borrow from it and expand it to come up with a definition more appropriate for en-wiki, but still as clear as the one at Simple.

The alternate name Edgeworth–Kuiper belt should not appear in the Lead at all, imho, but in the body somewhere. The policy WP:COMMONNAME governs here; and references to "Edgeworth-Kuiper" seem like a tiny minority. Also, "Edgeworth" is not among the top ten tokens appearing before "Kuiper belt" in English books. There is no policy based on primacy of discovery, for better or worse, and a very infrequent usage like this should not appear in the definition; possibly it could end up the last paragraph of the lead: "..and it is sometimes known as the E-K b. because of Kenneth Edgeworth's contributions."

Also, I'm not a fan of bare urls in any reference, much less in the first sentence,; and per WP:LEAD you don't need references in the lead of an article anyway, if the article is structured properly. Why aren't these references in the body, and properly expanded?

After removing the dictionary reference from the first sentence, I'd add a reference from a work in the field, rather than a dictionary entry, which is written by lexicographers, not science writers. I find some of the suggested wording in this book intended for a juvenile audience pretty satisfactory; here are some choices:

• a ring of small objects beyond Neptune (attributed to Kuiper)
• a band of rocky and icy objects past Neptune
• similar to the asteroid belt, but more icy

Taking all of the above into consideration, I'd like to propose a couple of possibilities for the lead sentence:

• The Kuiper belt (/ˈkaɪpər/) is a circumstellar disc centered on the Sun in the outer Solar System, extending from the orbit of Neptune (at 30 AU) to approximately 50 AU from the Sun.
• The Kuiper belt (/ˈkaɪpər/) is a a band of rocky and icy objects in the outer Solar System extending from the orbit of Neptune to approximately 50 AU from the Sun.

I prefer the second one. The main reason is, it states clearly what it is, without jargon, which is what a definition should do. It gives up "circumstellar disc", but that can be added back in sentence two. Overall, it leaves the first sentence quite clear. Thoughts? Mathglot (talk) 09:49, 2 February 2019 (UTC)

• I agree with your assessment in general. I'd prefer the first of your two lead sentence options, because "band" is not defined, and is ambiguous (not specifying orientation; does it stretch around the Sun, or radially away from the Sun, from Neptune to 50 AU?). "Ring of small objects" seems like a better option. "Similar to the asteroid belt, but more icy" is not very explanatory if you don't know what the asteroid belt is.
  I first thought the addition of "centered around the Sun" is unnecessary (silly), but it is true that the current lead section does leave ambiguity. With the changes you suggest to the first sentence, this becomes obsolete, but it could be done in the second sentence if the mention of "circumstellar disc" is moved there. Renerpho (talk) 07:20, 3 February 2019 (UTC)
  I'd like to add that the changes you are proposing might be substantial, if applied consistently (removing links from the lead, restructuring the article). This is a featured article so an overhaul of the lead section deserves to be properly discussed before it is implemented. I suggest you add a note to the WikiProject Astronomy and WikiProject Solar System talk pages, to invite participation in this discussion. Renerpho (talk) 07:31, 3 February 2019 (UTC)

@Renerpho: Thanks for your comments. Didn't notice that it was FA, and agree that it should be discussed in more detail in that case, before the lead is changed. Thanks for mentioning that. Re: "circmstellar disc": I was really hoping "circumsolar" was a word because that would have solved some of the problems with the current expression, but apparently it isn't; too bad. Mathglot (talk) 11:53, 3 February 2019 (UTC)

• Listed at WT:AST. Mathglot (talk) 11:49, 3 February 2019 (UTC)
• Listed at WT:SOLAR. Mathglot (talk) 11:49, 3 February 2019 (UTC)
• Listed at WT:ASTRO. Mathglot (talk) 11:49, 3 February 2019 (UTC)

---

References

Unlabeled objects in the lead image

The lead image shows green objects and "swamp green" objects. Green objects are labeled as centaurs. What are the "swamp green" objects and why are they unlabeled? — UnladenSwallow (talk) 10:54, 9 October 2019 (UTC)

I am not sure, but the category could be "other TNO", as used for example in Johnston's list. I suggest you ask the author of the original image. Renerpho (talk) 11:25, 9 October 2019 (UTC)

If so then it's the same category that I labeled swamp green in this diagram. Renerpho (talk) 11:31, 9 October 2019 (UTC)

Okay, maybe I'm colourblind (okay, definitely I'm colourblind), but the only green points I see are the centaurs. Whoever made the colour labels didn't choose a green that matches the plot very well, is that the source of confusion? (I say, hoping I didn't make the label) WilyD 11:33, 9 October 2019 (UTC)

Yeah, if you go back to the insertion, I just called centaurs green. I have no idea why someone added a colourbar with forest green for the swamp green I used WilyD 11:36, 9 October 2019 (UTC)

Thanks for the response, WilyD. There are two kinds of green used in the image. One that corresponds to centaurs, and a darker one (almost brown; UnladenSwallow calls it "swamp green") of unknown meaning. Renerpho (talk) 12:00, 9 October 2019 (UTC)

Ah, I just see from your insertion link that you labelled those as "scattered objects are dark green", right? Renerpho (talk) 12:01, 9 October 2019 (UTC)

The Centaurs are a very dark green colour. If there's another green used anywhere in the image, I can't find it. I could dig around for the code I used, but that was some years ago, and I'm liable not to find it. WilyD 12:04, 9 October 2019 (UTC)

See here, where I labelled the two kinds of green. Renerpho (talk) 12:28, 9 October 2019 (UTC)

Oh, yes, now I see it. Going back to the archives Talk:Kuiper_belt/Archive_2, you can see the forest green dots are centaurs, the mustard yellow dots are scattered disk, the pinkish dots labelled "scattered disk" are actually resonant objects, and the blue "kuiper belt objects" are classical kuiper belt objects (both hot and cold, normally I'd call mixing them an abomination against any and all gods, but I was probably following the minor planet centre. I'm not sure how that got mucked up. I WilyD 12:45, 9 October 2019 (UTC)

So, I fixed the colours and labels. Except, the colour boxen also have coloured edges, and I have no clew how those colours were decided, so they're essentially random now ? Cheerio WilyD 15:11, 9 October 2019 (UTC)

I've removed the box borders entirely. I think it looks fine. If you want them back, you can add |border=1px solid #0000003F parameter to {{legend2}}s—this will add borders of slightly darker shade than the colors of the boxen. — UnladenSwallow (talk) 23:18, 9 October 2019 (UTC)

Looks good to me. Thanks! Renerpho (talk) 23:48, 9 October 2019 (UTC)

2018 paper says mass of KB may be as low as 2% Earth's

https://link.springer.com/article/10.1007/s10569-018-9853-5 Serendi^podous 22:36, 26 November 2019 (UTC)

Fraser et al. estimates the mass at 0.01 M_earth https://arxiv.org/abs/1401.2157 Simulations have ended with similar estimated masses https://arxiv.org/abs/1602.06988 or somewhat larger masses 0.03 M_earth https://arxiv.org/abs/1706.07447 Agmartin (talk) 03:29, 27 November 2019 (UTC)

Yeah, Wes' 2014 paper is the reference this article should be using (for the total mass - the size distribultion - I think Sam Lawler and Kat Volk have some OSSOS papers that cover sub-populations that'd be more up to date). A lot of the article is pretty dated, and there's a tendency for new info to get added without dated stuff going - see how the size distribution starts discussion q = 4 like it's 2002, then two paragraphs later says "Oh, that's wrong though". WilyD 05:58, 27 November 2019 (UTC)

I've swapped it out, but I'm not really qualified to sort out the data in the mass/size distribution section. Serendi^podous 15:42, 27 November 2019 (UTC)

My inclination with articles this close to my own research is to try to be hands-offy and restrict myself to technical assistance (otherwise I tend to get pedantic and get really irritated when I have to represent the state of the literature where I know it's wrong, stuff like that). But I can try & go through and point people in the right direction if it's helpful. WilyD 16:38, 27 November 2019 (UTC)

Is the Kuiper belt a torus?

In multiple places the juicer belt is referred to as a torus, is it actually a solid torus. This is obviously a nitpick but if it is really a torus that seems mathematically interesting INLegred (talk) 20:04, 30 October 2022 (UTC)

It is, to a first approximation, an annulus; and, to a second approximation, a (stretched-out) torus. But all that means is that it looks circular from above (like an annulus), and it is the thickest near the "middle" of the annulus.

Saying that its shape is similar to a (stretched-out) torus is a bit like saying that the orbits of the planets are circular and co-planar. It's approximately true, but real life is more complicated. Not only is the true shape not actually a mathematical torus, the actual Kuiper belt also has a lot of internal structure. There are gaps due to resonances with Neptune, different populations with different orbital distributions, collisional families leading to clumps, etc. etc...

The Kuiper belt does not have the shape of a solid torus (the thing you get from rotating a circle around an axis), not even approximately. Renerpho (talk) 22:04, 31 October 2022 (UTC)

Naming

The article says "Reportedly because the words "Kuiper" and "comet belt" appeared in the opening sentence of Fernández's paper, Tremaine named this hypothetical region the "Kuiper belt".

That may well be true (I don't have access to the original source), but the fact is, that the opening sentence of that paper does not contain the word "Kuiper" (it's in the second sentence). I think either the source says "opening sentences" or something similar, or the article should maybe point out that he was mistaken. 109.193.183.233 (talk) 00:00, 8 May 2023 (UTC)

Discovery vs prediction

The current text contains a contradictory statement about the first prediction of the existence of the Kuiper belt. Kuiper is said to have conjectured its existence in 1951; later, the text says that Fernandez was the first to predict its existence. This seems problematic , as Fernandez was only 3 years old in 1951. omsharan (talk) 23:58, 9 December 2023 (UTC)

Kuiper cliff

I'm not competent to edit this article -- but an error may appear in the Kuiper cliff section. The suspicious text is "the number of large objects would increase by a factor of two beyond 50 AU, so this sudden drastic falloff, known as the Kuiper cliff, was unexpected"

Doesn't that language mean that the word "increase" should be replaced by "decrease"? If not, perhaps a clarification is needed. Smallchief (talk) 11:35, 7 September 2024 (UTC)

@Smallchief: You have to go back a little further in the sentence, to where it 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, so this sudden drastic falloff, known as the Kuiper cliff, was unexpected. Models and simulations had indicated that there should be an increase. What we actually saw when we looked was a decrease. The reason for that discrepancy, which has been called the Kuiper cliff, remains unknown. Renerpho (talk) 19:47, 7 September 2024 (UTC)