Editing Classical Kuiper belt object

{{Short description|Kuiper belt object, not controlled by an orbital resonance with Neptune}}
[[File:UltimaThule_CA06_color_20190516.png|thumb|[[486958 Arrokoth]], the first classical Kuiper belt object [[List of minor planets visited by spacecraft|visited by a spacecraft]].]]
[[File:Cubewanos.png|thumb|The orbits of various cubewanos compared to the orbit of [[Neptune]] (blue) and [[Pluto]] (pink)]]
{{TNO}}

A '''classical Kuiper belt object''', also called a '''cubewano''' ({{IPAc-en|ˌ|k|juː|b|iː|ˈ|w|ʌ|n|oʊ}} "QB1-o"),{{efn|Somewhat old-fashioned, but "cubewano" is still used by the Minor Planet Center for their list of Distant Minor Planets.<ref>{{cite web |url=http://www.minorplanetcenter.org/mpec/K10/K10S44.html |title=Distant Minor Planets}}</ref>}} is a low-eccentricity [[Kuiper belt]] object (KBO) that [[orbit]]s beyond [[Neptune]] and is not controlled by an [[Resonant trans-Neptunian object|orbital resonance with Neptune]]. Cubewanos have orbits with [[Semi-major axis|semi-major axes]] in the 40–50&nbsp;[[astronomical unit|AU]] range and, unlike [[Pluto]], do not cross Neptune's orbit. That is, they have low-[[Orbital eccentricity|eccentricity]] and sometimes low-[[Orbital inclination|inclination]] orbits like the classical planets.

The name "cubewano" derives from the first [[trans-Neptunian object]] (TNO) found after Pluto and [[Charon (moon)|Charon]]: [[15760 Albion]], which until January 2018 had only the provisional designation (15760) {{mp|1992 QB|1}}.<ref>{{cite web |url=http://www2.ess.ucla.edu/~jewitt/kb/def_classical.html |title=Classical Kuiper Belt Objects |author-link=David Jewitt |first=David |last=Jewitt |publisher=UCLA |access-date=1 July 2013}}</ref> Similar objects found later were often called "QB1-os", or "cubewanos", after this object, though the term "classical" is much more frequently used in the scientific literature.

Objects identified as cubewanos include:
* [[15760 Albion]]<ref name=K10B62 /> (aka {{mp|1992 QB|1}} and gave rise to term 'Cubewano')
* [[Makemake|136472 Makemake]], the largest known cubewano{{Citation needed|reason=This conflicts with the main page for Makemake, which claims that Makemake is the second largest cubewano.|date=January 2024}} and a [[dwarf planet]]<ref name=K10B62 /> 
* [[50000 Quaoar]] and [[20000 Varuna]], each considered the largest TNO at the time of discovery<ref name=K10B62 /> 
* [[19521 Chaos]], [[58534 Logos]], [[53311 Deucalion]], [[66652 Borasisi]], [[88611 Teharonhiawako]]
* {{mpl|(33001) 1997 CU|29}}, {{mpl|(55636) 2002 TX|300}}, {{mpl|(55565) 2002 AW|197}}, {{mpl|(55637) 2002 UX|25}}
* [[486958 Arrokoth]]

[[Haumea|136108 Haumea]] was provisionally listed as a cubewano by the [[Minor Planet Center]] in 2006,<ref name=K06X45>{{cite web |date=2006-12-12 |title=MPEC 2006-X45: Distant Minor Planets |url=https://minorplanetcenter.net//mpec/K06/K06X45.html |access-date=2008-10-03 |df=dmy-all |publisher=IAU Minor Planet Center & Tamkin Foundation Computer Network}}</ref> but was later found to be in a [[resonant trans-Neptunian object|resonant]] orbit.<ref name=K10B62>
{{cite web |date=2010-01-30 |title=MPEC 2010-B62: Distant Minor Planets (2010 FEB. 13.0 TT) |author=Brian G. Marsden |department=IAU Minor Planet Center |publisher=Harvard-Smithsonian Center for Astrophysics |url=http://www.minorplanetcenter.org/mpec/K10/K10B62.html |archive-url=https://archive.today/20120904012403/http://www.minorplanetcenter.org/mpec/K10/K10B62.html |url-status=dead |archive-date=2012-09-04 |df=dmy-all |access-date=2010-07-26}}</ref>

== {{vanchor|Orbits 'hot' and 'cold' populations}} ==
[[File:TheKuiperBelt 55AU Classical.svg|thumb|300px|[[Semimajor axis]] and [[orbital inclination|inclination]] of cubewanos (blue) compared to [[Resonant trans-Neptunian object|resonant TNOs]] (red).]]

There are two basic dynamical classes of classical Kuiper-belt bodies: those with relatively unperturbed ('cold') orbits, and those with markedly perturbed ('hot') orbits.

Most cubewanos are found between the 2:3 [[orbital resonance]] with Neptune (populated by [[plutino]]s) and the 1:2 resonance. [[50000 Quaoar]], for example, has a near-circular orbit close to the [[ecliptic]]. Plutinos, on the other hand, have more eccentric orbits bringing some of them closer to the Sun than [[Neptune]].

The majority of classical objects, the so-called ''cold population'', have low inclinations (<&thinsp;5[[Degree (angle)|°]]) and near-circular orbits, lying between 42 and 47&nbsp;AU. A smaller population (the ''hot population'') is characterised by highly inclined, more eccentric orbits.<ref name="JewittDelsanti2006">{{cite book |last1=Jewitt |first1=D. |author1-link=David Jewitt |last2=Delsanti |first2=A. |year=2006 |chapter=The Solar System Beyond The Planets |title=Solar System Update : Topical and Timely Reviews in Solar System Sciences |publisher=[[Springer (publisher)|Springer]]-[[Praxis Publishing|Praxis]] |chapter-url=http://www2.ess.ucla.edu/~jewitt/papers/2006/DJ06.pdf |isbn=978-3-540-26056-1 |url=http://www.ifa.hawaii.edu/faculty/jewitt/papers/2006/DJ06.pdf |access-date=March 2, 2006 |archive-url=https://web.archive.org/web/20070129151907/http://www.ifa.hawaii.edu/faculty/jewitt/papers/2006/DJ06.pdf |archive-date=2007-01-29 |df=dmy-all |url-status=dead}})</ref> The terms 'hot' and 'cold' has nothing to do with surface or internal temperatures, but rather refer to the orbits of the objects, by analogy to molecules in a gas, which increase their relative velocity as they heat up.<ref name="Levison2003">{{cite journal |last1=Levison |first1=Harold F. |last2=Morbidelli |first2=Alessandro |date=2003 |title=The formation of the Kuiper belt by the outward transport of bodies during Neptune's migration |journal=[[Nature (journal)|Nature]] |volume=426 |issue=6965 |pages=419–421 |doi=10.1038/nature02120 |pmid=14647375 |bibcode=2003Natur.426..419L|s2cid=4395099 }}</ref>

The [[Deep Ecliptic Survey]] reports the distributions of the two populations; one with the inclination centered at 4.6° (named ''Core'') and another with inclinations extending beyond 30° (''Halo'').<ref name="DES_Elliot2006">
{{cite journal |author=J. L. Elliot |year=2006 |title=The Deep Ecliptic Survey: A Search for Kuiper Belt Objects and Centaurs. II. Dynamical Classification, the Kuiper Belt Plane, and the Core Population |journal=[[Astronomical Journal]] |volume=129 |issue=2 |pages=1117–1162 |bibcode=2005AJ....129.1117E |doi=10.1086/427395 |display-authors=etal|doi-access=free }} ({{cite web |url=http://alpaca.as.arizona.edu/~trilling/des2.pdf |title=Preprint |archive-url=https://web.archive.org/web/20060823112517/http://alpaca.as.arizona.edu/~trilling/des2.pdf |archive-date=2006-08-23 |df=dmy-all}})</ref>

=== Distribution ===
The vast majority of KBOs (more than two-thirds) have inclinations of less than 5° and eccentricities of less than 0.1&nbsp;. Their semi-major axes show a preference for the middle of the main belt; arguably, smaller objects close to the limiting resonances have been either captured into resonance or have their orbits modified by Neptune.

The 'hot' and 'cold' populations are strikingly different: more than 30% of all cubewanos are in low inclination, near-circular orbits. The parameters of the plutinos’ orbits are more evenly distributed, with a local maximum in moderate eccentricities in 0.15–0.2 range, and low inclinations 5–10°.
See also the comparison with [[scattered disk#Scattered objects versus classical objects|scattered disk objects]].

Cubewanos form a clear 'belt' outside Neptune's orbit, whereas the plutinos approach, or even cross Neptune's orbit. When orbital inclinations are compared, 'hot' cubewanos can be easily distinguished by their higher inclinations, as the plutinos typically keep orbits <20°. The high inclination of 'hot' cubewanos has not been explained.<ref>
{{cite web |last=Jewitt |first=D. |author-link=David Jewitt |year=2004 |title=Plutino |url=http://www.ifa.hawaii.edu/~jewitt/kb/plutino.html |url-status=dead |archive-url=https://web.archive.org/web/20070419234021/http://www.ifa.hawaii.edu/~jewitt/kb/plutino.html |archive-date=2007-04-19 |df=dmy-all}}</ref>

{{multiple image
 |direction = horizontal
 |align= center
 |width1= 458
 |width2= 200
 |image1= KBOs and resonances.png
 |image2=TheKuiperBelt Projections 55AU Classical Plutinos.svg
 |footer=''Left:'' TNO distribution of cubewanos (blue), [[resonant trans-Neptunian object|resonant TNOs]] (red), [[Scattered disk object|SDO]]s (grey) and [[sednoid]]s (yellow). ''Right:'' Comparison of the aligned orbits (polar and ecliptic view) of cubewanos, plutinos, and Neptune (yellow).
}}
{{clear}}

== Cold and hot populations: physical characteristics ==
In addition to the distinct orbital characteristics, the two populations display different physical characteristics.

The difference in colour between the red cold population, such as [[486958 Arrokoth]], and more heterogeneous hot population was observed as early as in 2002.<ref name="Doressoundiram2002">
{{cite journal |author1=A. Doressoundiram |author2=N. Peixinho |author3=C. de Bergh |author4=S. Fornasier |author5=P. Thebault |author6=M. A. Barucci |author7=C. Veillet |title=The Color Distribution in the Edgeworth-Kuiper Belt |journal=The Astronomical Journal |date=October 2002 |arxiv=astro-ph/0206468 |bibcode=2002AJ....124.2279D |doi=10.1086/342447 |volume=124 |issue=4 |page=2279|s2cid=30565926 }}</ref>
Recent studies, based on a larger data set, indicate the cut-off inclination of 12° (instead of 5°) between the cold and hot populations and confirm the distinction between the homogenous red cold population and the bluish hot population.<ref name="LacerdaJewitt2008">
{{cite journal |first1=Nuno |last1=Peixinho |first2=Pedro |last2=Lacerda |first3=David |last3=Jewitt |author3-link=David Jewitt |title=Color-inclination relation of the classical Kuiper belt objects |journal=The Astronomical Journal |date=August 2008 |arxiv=0808.3025 |bibcode=2008AJ....136.1837P |doi=10.1088/0004-6256/136/5/1837 |volume=136 |issue=5 |pages=1837|s2cid=16473299 }}</ref>

Another difference between the low-inclination (cold) and high-inclination (hot) classical objects is the observed number of [[binary asteroid|binary objects]]. Binaries are quite common on low-inclination orbits and are typically similar-brightness systems. Binaries are less common on high-inclination orbits and their components typically differ in brightness. This correlation, together with the differences in colour, support further the suggestion that the currently observed classical objects belong to at least two different overlapping populations, with different physical properties and orbital history.<ref name="NollGrundy-binaries2008">
{{cite journal |author1=K. Noll |author2=W. Grundy |author3=D. Stephens |author4=H. Levison |author5=S. Kern |title=Evidence for two populations of classical transneptunian objects: The strong inclination dependence of classical binaries |journal=Icarus |date=April 2008 |arxiv=0711.1545 |bibcode=2008Icar..194..758N |doi=10.1016/j.icarus.2007.10.022 |volume=194 |issue=2 |pages=758|s2cid=336950 }}</ref>

== Toward a formal definition ==
There is no official definition of 'cubewano' or 'classical KBO'. However, the terms are normally used to refer to objects free from significant perturbation from Neptune, thereby excluding KBOs in orbital resonance with Neptune ([[resonant trans-Neptunian object]]s). The [[Minor Planet Center]] (MPC) and the [[Deep Ecliptic Survey]] (DES) do not list cubewanos (classical objects) using the same criteria. Many TNOs classified as cubewanos by the MPC, such as dwarf planet [[Makemake]], are classified as ScatNear (possibly [[Perturbation (astronomy)|scattered]] by Neptune) by the DES. {{mpl|(119951) 2002 KX|14}} may be an inner cubewano near the [[plutino]]s. Furthermore, there is evidence that the Kuiper belt has an 'edge', in that an apparent lack of low-inclination objects beyond 47–49&nbsp;AU was suspected as early as 1998 and shown with more data in 2001.<ref name="Trujillo 2001">
{{cite journal |last1=Trujillo |first1=Chadwick A. |last2=Brown |first2=Michael E. |year=2001 |title=The Radial Distribution of the Kuiper Belt |url=http://www.gps.caltech.edu/~chad/publications/2001-trujillo-brown.pdf |journal=The Astrophysical Journal |volume=554 |issue=1 |pages=L95–L98 |bibcode=2001ApJ...554L..95T |doi=10.1086/320917 |s2cid=7982844 |url-status=dead |archive-url=https://web.archive.org/web/20060919003142/http://www.gps.caltech.edu/~chad/publications/2001-trujillo-brown.pdf |archive-date=2006-09-19 |df=dmy-all}}</ref> Consequently, the traditional usage of the terms is based on the orbit's semi-major axis, and includes objects situated between the 2:3 and 1:2 resonances, that is between 39.4 and 47.8 AU (with exclusion of these resonances and the minor ones in-between).<ref name="JewittDelsanti2006"/>

These definitions lack precision: in particular the boundary between the classical objects and the [[scattered disk]] remains blurred. {{Asof|2023}}, there are 870 objects with perihelion (q) > 40 AU and aphelion (Q) < 48 AU.<ref name="MPC_list"/>

=== DES classification ===
Introduced by the report from the [[Deep Ecliptic Survey]] by J. L. Elliott et al. in 2005 uses formal criteria based on the mean orbital parameters.<ref name="DES_Elliot2006" /> Put informally, the definition includes the objects that have never crossed the orbit of Neptune. According to this definition, an object qualifies as a classical KBO if:
* it is not [[Resonant trans-Neptunian object|resonant]]
* its average [[Tisserand's parameter]] with respect to Neptune exceeds 3
* its average eccentricity is less than 0.2.

=== SSBN07 classification ===
An alternative classification, introduced by [[Brett J. Gladman|B. Gladman]], [[Brian G. Marsden|B. Marsden]] and C. van Laerhoven in 2007, uses a 10-million-year orbit integration instead of the Tisserand's parameter. Classical objects are defined as not resonant and not being currently scattered by Neptune.<ref name="ArizonaBook_Gladman2007">
{{cite book |last1=Gladman |first1=B. J. |last2=Marsden |first2=B. |last3=van Laerhoven |first3=C. |year=2008 |chapter=Nomenclature in the Outer Solar System |title=The Solar System Beyond Neptune |chapter-url=http://www.lpi.usra.edu/books/ssbn2008/7002.pdf |archive-url=https://web.archive.org/web/20121102205338/http://www.lpi.usra.edu/books/ssbn2008/7002.pdf |archive-date=2012-11-02 |url-status=live |editor-last=Barucci |editor-first=M. A. |publisher=University of Arizona Press |location=Tucson |isbn=978-0-8165-2755-7 |display-editors=etal}}</ref>

Formally, this definition includes as ''classical'' all objects with their ''current'' orbits that
*are non-resonant (see the [[Resonant trans-Neptunian object#Classification methods|definition of the method]])
*have a semi-major axis greater than that of Neptune (30.1 AU; i.e. excluding centaurs) but less than 2000 AU (to exclude inner-Oort-cloud objects)
*are not being scattered by Neptune
*have their eccentricity <math>e < 0.240</math> (to exclude detached objects)
Unlike other schemes, this definition includes the objects with major semi-axis less than 39.4 AU (2:3 resonance)—termed '''''inner classical belt''''', or more than 48.7 (1:2 resonance) – termed '''''outer classical belt''''', and reserves the term '''''main classical belt''''' for the orbits between these two resonances.<ref name="ArizonaBook_Gladman2007" />

== Families ==
The first known [[collisional family]] in the classical Kuiper belt—a group of objects thought to be remnants from the breakup of a single body—is the [[Haumea family]].<ref name="BrownBarkume2007">
{{cite journal |last1=Brown |first1=Michael E. |last2=Barkume |first2=Kristina M. |last3=Ragozzine |first3=Darin |last4=Schaller |first4=Emily L. |year=2007 |title=A collisional family of icy objects in the Kuiper belt |journal=Nature |volume=446 |issue=7133 |pages=294–6 |bibcode=2007Natur.446..294B |doi=10.1038/nature05619 |pmid=17361177 |s2cid=4430027 |url=https://authors.library.caltech.edu/34346/2/nature05619-s1.pdf |archive-url=https://web.archive.org/web/20180723192004/https://authors.library.caltech.edu/34346/2/nature05619-s1.pdf |archive-date=2018-07-23 |url-status=live}}</ref> It includes Haumea, its moons, {{mpl|2002 TX|300}} and seven smaller bodies.{{efn|As of 2008. The four brightest objects of the family are situated on the graphs ''inside'' the circle representing Haumea.{{clarify|reason=What graphs is this note referring to?|date=July 2023}}}} The objects not only follow similar orbits but also share similar physical characteristics. Unlike many other KBO their surface contains large amounts of water ice (H<sub>2</sub>O) and no or very little [[tholin]]s.<ref name="Pinilla-Alonso2009">
{{cite journal |last1=Pinilla-Alonso |first1=N. |last2=Brunetto |first2=R. |last3=Licandro |first3=J. |last4=Gil-Hutton |first4=R. |last5=Roush |first5=T. L. |last6=Strazzulla |first6=G. |year=2009 |title=The surface of (136108) Haumea ({{mp|2003 EL|61}}), the largest carbon-depleted object in the trans-Neptunian belt |journal=Astronomy and Astrophysics |volume=496 |issue=2 |pages=547 |arxiv=0803.1080 |bibcode=2009A&A...496..547P |doi=10.1051/0004-6361/200809733|s2cid=15139257 }}</ref> The surface composition is inferred from their neutral (as opposed to red) colour and deep absorption at 1.5 and 2. [[micrometre|μm]] in [[infrared]] [[electromagnetic spectrum|spectrum]].<ref name="Pinilla-Alonso2007">
{{cite journal |last1=Pinilla-Alonso |first1=N. |last2=Licandro |first2=J. |last3=Gil-Hutton |first3=R. |last4=Brunetto |first4=R. |year=2007 |title=The water ice rich surface of (145453) 2005 RR<sub>43</sub>: a case for a carbon-depleted population of TNOs? |journal=Astronomy and Astrophysics |volume=468 |issue=1 |pages=L25–L28 |arxiv=astro-ph/0703098 |bibcode=2007A&A...468L..25P |doi=10.1051/0004-6361:20077294|s2cid=18546361 }}</ref> Several other collisional families might reside in the classical Kuiper belt.<ref name=chiang>{{cite journal |last1=Chiang |first1=E.-I. |title=A Collisional Family in the Classical Kuiper Belt |journal=[[The Astrophysical Journal]] |date=July 2002 |volume=573 |issue=1 |pages=L65–L68 |arxiv=astro-ph/0205275 |doi=10.1086/342089 |bibcode=2002ApJ...573L..65C |s2cid=18671789 }}</ref><ref name=pairs>{{cite journal |last1=de la Fuente Marcos |first1=Carlos |last2=de la Fuente Marcos |first2=Raúl |title=Dynamically correlated minor bodies in the outer Solar system |journal=[[Monthly Notices of the Royal Astronomical Society]] |date=11 February 2018 |volume=474 |issue=1 |pages=838–846 |arxiv=1710.07610 |doi=10.1093/mnras/stx2765 |doi-access=free |bibcode=2018MNRAS.474..838D|s2cid=73588205 }}</ref>

== Exploration ==
[[File:2014 MU69 orbit.jpg|thumb|New Horizons trajectory and the orbits of Pluto and 486958 Arrokoth]]

As of January 2019, only one classical Kuiper belt object has been observed up close by spacecraft. Both [[Voyager program|Voyager spacecraft]] have passed through the region before the discovery of the Kuiper belt.<ref>{{cite web |url=http://pluto.jhuapl.edu/News-Center/PI-Perspectives.php?page=piPerspective_02_28_2018 |title=The PI's Perspective: Why Didn't Voyager Explore the Kuiper Belt? |date=28 February 2018 |first=Alan |last=Stern |access-date=13 March 2018}}</ref> [[New Horizons]] was the first mission to visit a classical KBO. After its successful exploration of the [[Pluto]] system in 2015, the [[NASA]] spacecraft has visited the small KBO 486958 Arrokoth at a distance of {{convert|3500|km|mi}} on 1&nbsp;January 2019.<ref>{{cite web |url=http://www.planetary.org/blogs/emily-lakdawalla/2018/0124-new-horizons-prepares-for-2014mu69.html |title=New Horizons prepares for encounter with 2014&nbsp;MU69 |first=Emily |last=Lakdawalla |publisher=Planetary Society |date=24 January 2018 |access-date=13 March 2018}}</ref>

== List ==
{{Main list|List of trans-Neptunian objects#List}}

Here is a very generic list of classical Kuiper belt objects. {{As of|2023|7}}, there are about 870&nbsp;objects with {{nowrap|q > 40 AU}} and {{nowrap|Q < 48 AU}}.<ref name="MPC_list">{{cite web |url=http://minorplanetcenter.net/db_search/show_by_properties?perihelion_distance_min=40&aphelion_distance_max=48 |title={{nowrap|q > 40 AU}} and {{nowrap|Q < 48 AU}} |website=minorplanetcenter.net |department=IAU Minor Planet Center |publisher=Harvard-Smithsonian Center for Astrophysics |access-date=31 July 2023}}</ref>
{{Colbegin}}
* [[15760 Albion]]
* [[20000 Varuna]]
* {{mpl|(307261) 2002 MS|4}}
* {{mpl|(307616) 2003 QW|90}}
* {{mpl|(444030) 2004 NT|33}}
* {{mpl|(308193) 2005 CB|79}}
* {{mpl|(119951) 2002 KX|14}}
* {{mpl|(120178) 2003 OP|32}}
* [[120347 Salacia]]
* {{mpl|(144897) 2004 UX|10}}
* {{mpl|(145452) 2005 RN|43}}
* {{mpl|(145453) 2005 RR|43}}
* [[148780 Altjira]]
* {{mpl|(15807) 1994 GV|9}}
* {{mpl|(16684) 1994 JQ|1}}
* [[174567 Varda]]
* {{mpl|(19255) 1994 VK|8}}
* [[19521 Chaos]]
* {{mpl|(202421) 2005 UQ|513}}
* {{mpl|(24835) 1995 SM|55}}
* {{mpl|(24978) 1998 HJ|151}}
* {{mpl|(278361) 2007 JJ|43}}
* {{mpl|(33001) 1997 CU|29}}
* [[486958 Arrokoth]]
* [[50000 Quaoar]]
* {{mpl|(52747) 1998 HM|151}}
* [[53311 Deucalion]]
* {{mpl|(55565) 2002 AW|197}}
* {{mpl|(55636) 2002 TX|300}}
* {{mpl|(55637) 2002 UX|25}}
* [[58534 Logos]]
* [[66652 Borasisi]]
* {{mpl|(69987) 1998 WA|25}}
* [[79360 Sila–Nunam]]
* {{mpl|(79983) 1999 DF|9}}
* {{mpl|(85627) 1998 HP|151}}
* {{mpl|(85633) 1998 KR|65}}
* {{mpl|(86047) 1999 OY|3}}
* [[88611 Teharonhiawako]]
* {{mpl|(90568) 2004 GV|9}}
{{Colend}}

== See also ==
* [[Lists of astronomical objects]]

== Footnotes ==
{{notelist|1}}

== References ==
{{reflist|25em}}

==External links==
{{Commonscat|Classical Kuiper belt objects}}
*{{cite web |first=David |last=Jewitt |author-link=David Jewitt |url=http://www2.ess.ucla.edu/~jewitt/kb.html |title=Kuiper belt site |publisher=UCLA}}
*{{cite web |url=http://www.boulder.swri.edu/ekonews/ |title=The Kuiper Belt Electronic Newsletter}}
*{{citation |department=IAU Minor Planet Center |publisher=Harvard-Smithsonian Center for Astrophysics |url=http://www.minorplanetcenter.org/iau/lists/TNOs.html |website=minorplanetcenter.org |url-status=dead |archive-url=https://web.archive.org/web/20100827234817/http://www.minorplanetcenter.org/iau/lists/TNOs.html |archive-date=2010-08-27 |df=dmy-all |title=List of Trans-Neptunian objects}}
*{{cite web |title=TNO pages |url=http://www.johnstonsarchive.net/astro/tnos.html |website=johnstonarchive.net}}
*{{cite web |title=Plot of the current positions of bodies in the Outer Solar System |url=http://www.minorplanetcenter.org/iau/lists/OuterPlot.html |website=minorplanetcenter.org |department=IAU Minor Planet Center |publisher=Harvard-Smithsonian Center for Astrophysics }}

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{{DEFAULTSORT:Classical Kuiper belt object}}
[[Category:Classical Kuiper belt objects| ]]