View source for Astronomy:Eris (dwarf planet)

{{Short description|Dwarf planet beyond Pluto in the Solar System}}
{{Infobox planet
| minorplanet      = yes
| background       = #C2E0FF
| name             = 136199 Eris
| symbol           = [[File:Eris symbol (bold).svg|24px|⯰<!--used i.a. by JPL/NASA-->]] (mostly astrological)
| image            = Eris and dysnomia2.jpg
| image_alt        = Eris (center) and Dysnomia (left); image taken by the Hubble Space Telescope
| caption          = Eris (center) and [[Astronomy:Dysnomia (moon)|Dysnomia]] (left of center); image taken by the [[Astronomy:Hubble Space Telescope|Hubble Space Telescope]]
| discoverer       =
  {{plainlist |
* [[Biography:Michael E. Brown|M. E. Brown]]
* [[Biography:Chad Trujillo|C. A. Trujillo]]
* [[Biography:David L. Rabinowitz|D. L. Rabinowitz]]<ref name="discovery" />
  }}
| discovered       = January 5, 2005<ref name="New Planet" />
| mpc_name         = (136199) Eris
| pronounced       = {{IPAc-en|ˈ|ɛr|ᵻ|s}},<ref name=Lex>{{Cite dictionary |url=http://www.lexico.com/definition/Eris |archive-url=https://web.archive.org/web/20200731013201/https://www.lexico.com/definition/eris |archive-date=July 31, 2020 |title=Eris |dictionary=Lexico UK English Dictionary |publisher=[[Organization:Oxford University Press|Oxford University Press]]}}<br />{{MW|Eris}}</ref><ref name=dictcom/> {{IPAc-en|ˈ|ɪər|ᵻ|s}}<ref name=MW>Noah Webster (1884) ''A Practical Dictionary of the English Language''</ref><ref name="dictcom">{{dict.com|Eris}}</ref>
| adjective        = Eridian {{IPAc-en|ɛ|'|r|ɪ|d|i|ə|n}}<ref name=Morrison/><ref name=ID>Ian Douglas (2013) ''Semper Human''</ref>
| note             = yes
| alt_names        = {{mp|2003 UB|313}}<ref name="jpldata" /><br />Xena (nickname)
| named_after      = [[Astronomy:Eris (mythology)|Ἔρις]] ''Eris''
| mp_category      =
  {{plainlist |
* [[Astronomy:Dwarf planet|Dwarf planet]]
* [[Astronomy:Trans-Neptunian object|TNO]]
* [[Astronomy:Scattered disc|SDO]]
* Binary<ref name="MPC" /><ref name="Buie2007" />
  }}
| orbit_ref        = <ref name="jpldata" />
| epoch            = May 31, 2020<br />([[Astronomy:Julian day|JD]] 2459000.5)
| aphelion         = {{cvt|97.457|AU|Tm|sigfig=5|lk=on}}
| perihelion       = {{cvt|38.271|AU|Tm|sigfig=4}}
| time_periastron  = ≈ 1 December 2257<ref name="Horizons2257"/><br />±11 days
| semimajor        = {{cvt|67.864|AU|Tm|sigfig=5}}
| eccentricity     = 0.43607
| period           = {{nowrap|559.07 [[Astronomy:Julian year|yr]] (204,199 [[Day|d]])}}
| avg_speed        = {{val|3.434|u=km/s}}
| mean_anomaly     = {{val|205.989|ul=°}}
| mean_motion      = {{Deg2DMS|0.00175200|sup=ms}} / day
| inclination      = {{val|44.040|u=°}}
| asc_node         = {{val|35.951|u=°}}
| arg_peri         = {{val|151.639|u=°}}
| earliest_precovery_date = September 3, 1954
| satellites       = [[Astronomy:Dysnomia (moon)|Dysnomia]]
| mean_diameter    = {{val|2326|12|u=km}}
| mean_radius      = {{val|1163|6|u=km}}<ref name="sicardy" /><ref name="Beatty2010-NewScientist" />
| mass             =
  {{plainlist |
* {{val|1.6466|0.0085|e=22|u=kg}} (system)<ref name="Holler2021" />
* {{val|1.638|0.014|e=22|u=kg}} (Eris only){{efn|name=erismass}}
* 0.0027 [[Astronomy:Earth mass|Earths]]; 0.22 Moons
  }}
| surface_area     = {{val|1.70|0.02|e=7|u=km2}}{{refn|group=lower-alpha|name=volumesurface|Calculated from the mean radius}}
| volume           = {{val|6.59|0.10|e=9|u=km3}}{{refn|group=lower-alpha|name=volumesurface}}
| density          = {{val|2.43|0.05|u=g/cm3}}<ref name="Holler2021" />
| surface_grav     = {{val|0.82|0.02|u=m/s<sup>2</sup>}}<br />{{val|0.084|0.002}} [[Physics:G-force|''g'']]{{refn|group=lower-alpha|name=calc|Calculated based on the known parameters}}
| escape_velocity  = {{V2|16.65|1163|2}}&thinsp;±&thinsp;0.01 km/s{{refn|group=lower-alpha|name=calc}}
| sidereal_day     = {{val|15.786|u=d}} ([[Astronomy:Tidal locking|synchronous]])<ref name="Szakats2022"/>
| axial_tilt       = ≈ {{val|78.3|u=°}} to orbit (assumed){{refn|name=tilt|group=lower-alpha|Assumed axial tilt if Eris rotates in the same plane as Dysnomia's orbit, which is tilted 78.29° with respect to Eris's orbit.<ref name="Holler2021" />}}<ref name="Holler2018" /><br/>≈ {{val|61.6|u=°}} to [[Astronomy:Ecliptic|ecliptic]] (assumed){{refn|name=tilt|group=lower-alpha}}{{efn|name=ecliptictilt|Holler et al. (2021) determined an ecliptic latitude of {{mvar|β}} {{=}} 28.41° for the north pole of Dysnomia's orbit, which is assumed to be similarly oriented as Eris's rotational north pole.<ref name="Holler2021"/><ref name="Holler2018"/>  {{mvar|β}}  is the angular offset from the ecliptic plane, whereas inclination  {{mvar|i}}  with respect to the ecliptic is the angular offset from the ecliptic north pole at {{nobr| {{mvar|β}} {{=}} +90° ;}}  {{mvar|i}}  with respect to the ecliptic would be the [[Angle#Combining angle pairs|complement]] of  {{mvar|β}}. Therefore, given {{nobr| {{mvar|β}} {{=}} 28.41° ,}}  {{nobr| {{mvar|i}} {{=}} 90° – (28.41°) {{=}} 61.59° }} from the ecliptic.}}
| albedo           = {{val|0.96|+0.09|-0.04}} {{sic}}<!--this isn't backwards--> [[Physics:Geometric albedo|geometric]]<ref name="sicardy" /><br />{{val|0.99|+0.01|-0.09}} [[Physics:Bond albedo|Bond]]<ref name="Verbiscer2022" />
| temp_name1       = (approx)
| min_temp_1       = 30&nbsp;[[Kelvin|K]]
| mean_temp_1      = 42&nbsp;K<ref>{{cite web |title=Eris Facts |url=https://space-facts.com/eris/ |website=Space Facts |access-date=May 26, 2021 |archive-date=May 28, 2023 |archive-url=https://web.archive.org/web/20230528054504/https://space-facts.com/eris/ |url-status=live }}</ref>
| max_temp_1       = 56&nbsp;K
| spectral_type    = [[Astronomy:Trans-Neptunian object#Colors|B−V]]=0.78, V−R=0.45<ref name="Snodgrass et al. 2010" />
| magnitude        = 18.7<ref name="AstDys" />
| abs_magnitude    = –1.21<ref name="jpldata" />
| angular_size     = {{val|34.4|1.4}} milli-arcsec<ref name="Brown-2003-UB313" />
}}

<!--Please check talk page before editing about any related Eris/Pluto size issues
-->
'''Eris''' ([[Astronomy:Minor-planet designation|minor-planet designation]] '''136199 Eris''') is the most [[Physics:Mass|mass]]ive and second-largest known [[Astronomy:Dwarf planet|dwarf planet]] in the [[Astronomy:Solar System|Solar System]].<ref>{{Cite web |url=https://www.asc-csa.gc.ca/eng/astronomy/solar-system/dwarf-planets.asp |title=Dwarf Planets |date=March 12, 2020 |accessdate=January 1, 2023 |publisher=[[Organization:Canadian Space Agency|Canadian Space Agency]] |archive-date=November 26, 2020 |archive-url=https://web.archive.org/web/20201126072537/https://www.asc-csa.gc.ca/eng/astronomy/solar-system/dwarf-planets.asp |url-status=live }}</ref> It is a [[Astronomy:Trans-Neptunian object|trans-Neptunian object]] (TNO) in the [[Astronomy:Scattered disc|scattered disk]] and has a high-[[Astronomy:Orbital eccentricity|eccentricity]] orbit. Eris was discovered in January 2005 by a [[Organization:Palomar Observatory|Palomar Observatory]]–based team led by [[Biography:Michael E. Brown|Mike Brown]] and verified later that year. In September 2006, it was named after the Greco{{En dash}}Roman [[Astronomy:Eris (mythology)|goddess of strife and discord]]. Eris is the [[Astronomy:List of Solar System objects by size|ninth-most massive known object]] orbiting the [[Astronomy:Sun|Sun]] and the sixteenth-most massive overall in the [[Astronomy:Solar System|Solar System]] (counting [[Astronomy:Natural satellite|moons]]). It is also the largest known object in the solar system that has not been visited by a spacecraft. Eris has been measured at {{convert|2326|±|12|km|sp=us|0}} in diameter;<ref name="sicardy" /> its mass is 0.28% that of the [[Astronomy:Earth mass|Earth]] and 27% greater than that of [[Astronomy:Pluto|Pluto]],<ref name="Brown Schaller 2007" /><ref name="070614_eris_mass" /> although Pluto is slightly larger by volume.<ref name="NASA Pluto larger 2015" /> Both Eris and Pluto have a surface area that is comparable to the area of {{wipe|Russia}} or [[Earth:South America|South America]].

Eris has one large known [[Astronomy:Natural satellite|moon]], [[Astronomy:Dysnomia (moon)|Dysnomia]]. In February 2016, Eris's distance from the Sun was {{convert|96.3|AU|e9km e9mi|abbr=unit}},<ref name="AstDys" /> more than three times that of [[Astronomy:Neptune|Neptune]] or Pluto. With the exception of long-period comets, Eris and Dysnomia were the most distant known natural objects in the Solar System until the discovery of {{mpl|2018 AG|37}} and {{mpl|2018 VG|18}} in 2018.<ref name="AstDys" />

Because Eris appeared to be larger than Pluto, [[Organization:NASA|NASA]] initially described it as the Solar System's [[Astronomy:Planets beyond Neptune|tenth planet]]. This, along with the prospect of other objects of similar size being discovered in the future, motivated the [[Organization:International Astronomical Union|International Astronomical Union]] (IAU) to [[Astronomy:Definition of planet|define the term ''planet'']] for the first time. Under the [[Astronomy:IAU definition of planet|IAU definition]] approved on August 24, 2006, Eris, Pluto and [[Astronomy:Ceres (dwarf planet)|Ceres]] are "dwarf planets",<ref name= IAUPressRelease2006 /> reducing the number of known planets in the Solar System to eight, the same as before Pluto's discovery in 1930. Observations of a stellar [[Astronomy:Occultation|occultation]] by Eris in 2010 showed that it was slightly smaller than Pluto,<ref name="Brown2010-occult" /><ref name="Brown2010-Plutosize" /> which was measured by ''[[Astronomy:New Horizons|New Horizons]]'' as having a mean diameter of {{convert|2377|±|4|km|sp=us|0}} in July 2015.<ref name="Measurement">{{cite web|url=http://www.nasa.gov/feature/how-big-is-pluto-new-horizons-settles-decades-long-debate/|title=How Big Is Pluto? New Horizons Settles Decades-Long Debate|year=2015|access-date=July 13, 2015|publisher=[[Organization:NASA|NASA]]|archive-url=https://web.archive.org/web/20150713175323/http://www.nasa.gov/feature/how-big-is-pluto-new-horizons-settles-decades-long-debate/|archive-date=July 13, 2015|url-status=live}}</ref><ref name="Pluto System after New Horizons">{{Cite journal |last1=Stern |first1=S. A. |last2=Grundy |first2=W. |last3=McKinnon |first3=W. B. |last4=Weaver |first4=H. A. |last5=Young |first5=L. A. |display-authors=2 |date=September 2018 |title=The Pluto System After ''New Horizons'' |url=https://www.annualreviews.org/doi/10.1146/annurev-astro-081817-051935 |journal=Annual Review of Astronomy and Astrophysics |volume=56 |pages=357–392 |arxiv=1712.05669 |bibcode=2018ARA&A..56..357S |doi=10.1146/annurev-astro-081817-051935 |access-date=April 5, 2022 |s2cid=119072504 |archive-date=October 21, 2022 |archive-url=https://web.archive.org/web/20221021142559/https://www.annualreviews.org/doi/10.1146/annurev-astro-081817-051935 |url-status=live }}</ref>

== Discovery ==
Eris was discovered by the team of [[Biography:Michael E. Brown|Mike Brown]], [[Biography:Chad Trujillo|Chad Trujillo]], and [[Biography:David L. Rabinowitz|David Rabinowitz]]<ref name="New Planet" /> on January 5, 2005, from images taken on October 21, 2003.<ref name="Brown-AJ2005-635"/> The discovery was announced on July 29, 2005, the same day as {{dp|Makemake}} and two days after {{dp|Haumea}},<ref name="MaughJohnson" /> due in part to [[Astronomy:Controversy over the discovery of Haumea|events that would later lead to controversy about Haumea]]. The search team had been systematically scanning for large outer [[Astronomy:Solar System|Solar System]] bodies for several years, and had been involved in the discovery of several other large TNOs, including [[Astronomy:50000 Quaoar|50000 Quaoar]], [[Astronomy:90482 Orcus|90482 Orcus]], and [[Astronomy:90377 Sedna|90377 Sedna]].<ref name="Schilling2008" />

Routine observations were taken by the team on October 21, 2003, using the 1.2&nbsp;m [[Astronomy:Samuel Oschin telescope|Samuel Oschin]] [[Astronomy:Schmidt telescope|Schmidt telescope]] at [[Organization:Palomar Observatory|Palomar Observatory]], California, but the image of Eris was not discovered at that point due to its very slow motion across the sky: The team's automatic image-searching software excluded all objects moving at less than 1.5&nbsp;[[Arcsecond|arcsecond]]s per hour to reduce the number of false positives returned.<ref name="Brown-AJ2005-635"/> When [[Astronomy:90377 Sedna|Sedna]] was discovered in 2003, it was moving at 1.75&nbsp;arcsec/h, and in light of that the team reanalyzed their old data with a lower limit on the angular motion, sorting through the previously excluded images by eye. In January 2005, the re-analysis revealed Eris's slow orbital motion against the background [[Astronomy:Star|star]]s.<ref name="Brown-AJ2005-635"/>

[[File:2003 UB313 confronto pt.jpg|thumb|left|upright=2|Relative distances and sizes of the classical planets, Pluto and Eris]]

Follow-up observations were then carried out to make a preliminary determination of Eris's [[Physics:Orbit|orbit]], which allowed the object's distance to be estimated.<ref name="Brown-AJ2005-635"/> The team had planned to delay announcing their discoveries of the bright objects Eris and {{dp|Makemake}} until further observations and calculations were complete, but announced them both on July 29 when the discovery of another large TNO they had been tracking—{{dp|Haumea}}—was [[Astronomy:Controversy over the discovery of Haumea|controversially announced]] on July 27 by a different team in Spain.<ref name="New Planet" />

[[Astronomy:Precovery|Precovery]] images of Eris have been identified back to September 3, 1954.<ref name="jpldata" />

More observations released in October 2005 revealed that Eris has a moon, later named [[Astronomy:Dysnomia (moon)|Dysnomia]]. Observations of Dysnomia's orbit permitted scientists to determine the mass of Eris, which in June 2007 was calculated to be {{val|1.66|0.02|e=22|u=kg}},<ref name="Brown Schaller 2007" /> {{val|27|2|u=%}} greater than Pluto's.

== Name ==
Eris is named after the [[Religion:Greek mythology|Greek]] goddess ''[[Astronomy:Eris (mythology)|Eris]]'' (Greek {{lang|grc|Ἔρις}}), a personification of strife and discord.<ref name="USGS-UB-313" /> The name was proposed by the Caltech team on September 6, 2006, and it was assigned on September 13, 2006,<ref>{{cite web|url=http://web.gps.caltech.edu/~mbrown/planetlila/|title=New Planet|first=Mike|last=Brown|website=web.gps.caltech.edu|access-date=January 5, 2010|archive-url=https://web.archive.org/web/20120517130215/http://web.gps.caltech.edu/~mbrown/planetlila/|archive-date=May 17, 2012|url-status=live}}</ref> following an unusually long period in which the object was known by the [[Astronomy:Provisional designation in astronomy|provisional designation]] '''{{mp|2003 UB|313}}''', which was granted automatically by the IAU under their naming protocols for [[Astronomy:Minor planet|minor planet]]s.

The name ''Eris'' has two competing pronunciations, with a "long" or with a "short" ''e'', analogous to the two competing pronunciations of the word ''[[Physics:Era|era]]''.<ref name="dictcom"/> Perhaps the more common form in English, used i.a. by Brown and his students,<ref name="pluggd.tv-2007" /> is {{IPAc-en|ˈ|ɛr|ᵻ|s}} with disyllabic laxing and a short ''e''.<ref name=Lex/> However, the classical English pronunciation of the goddess is {{IPAc-en|ˈ|ɪər|ᵻ|s}}, with a long ''e''.<ref name=MW/> 

The Greek and Latin oblique stem of the name is ''Erid-'',<ref>{{L&S|Eris|ref}}</ref> as can be seen in Italian ''Eride'' and Russian Эрида ''Erida'', so the adjective in English is ''Eridian'' {{IPAc-en|ɛ|'|r|ɪ|d|i|ə|n}}.<ref name=Morrison>{{Cite web|url=http://astrobiology.nasa.gov/ask-an-astrobiologist/question/?id=2971|archive-url=https://web.archive.org/web/20090425125638/http://astrobiology.nasa.gov/ask-an-astrobiologist/question/?id=2971|title=David Morrison (2008) ''Ask an Astrobiologist''|archive-date=April 25, 2009}}</ref><ref name=ID/>

=== Xena ===
Due to uncertainty over whether the object would be classified as a [[Astronomy:Planet|planet]] or a [[Astronomy:Minor planet|minor planet]], because varying nomenclature procedures apply to these classes of objects,<ref name="IAU-2003-UB313" /> the decision on what to name the object had to wait until after the August 24, 2006, IAU ruling.<ref name="IAUC 8747" /> For a time the object became known to the wider public as ''Xena''. "Xena" was an informal name used internally by the discovery team, inspired by the title character of the television series ''Xena: Warrior Princess''. The discovery team had reportedly saved the nickname "Xena" for the first body they discovered that was larger than Pluto. According to Brown,

{{Blockquote|We chose it since it started with an X ([[Astronomy:Planet X|planet "X"]]), it sounds mythological ... and we've been working to get more female deities out there (''e.g.'' [[Astronomy:90377 Sedna|Sedna]]). Also, at the time, the TV&nbsp;show was still on TV, which shows you how long we've been searching!<ref name="AAS-XenaGabrielle" />}}

Brown said in an interview that the naming process was stalled:

{{Blockquote|One reporter [Ken Chang]<ref>{{cite book|title=How I Killed Pluto and Why it Had it Coming|author=Mike Brown|year=2012|publisher=Spiegel & Grau|page=159}}</ref> called me up from ''{{wipe|The New York Times}}'' who happened to have been a friend of mine from college, [and] ... asked me, "What's the name you guys proposed?" and I said, "Well, I'm not going to tell." And he said, "Well, what do you guys call it when you're just talking amongst yourselves?"&nbsp;... As far as I remember this was the only time I told anybody this in the press, and then it got everywhere, which I only sorta felt bad about; I kinda like the name.<ref name="WGBH" />}}

=== Choosing an official name ===
[[File:Animation showing movement of 2003 UB313-2-.gif|thumb|left|Animation showing the movement of Eris on the images used to discover it. Eris is indicated by the arrow. The three frames were taken over a period of three hours.]]
According to science writer Govert Schilling, Brown initially wanted to call the object "[[Philosophy:Lila (Hinduism)|Lila]]", after a concept in [[Religion:Hindu mythology|Hindu mythology]] that described the cosmos as the outcome of a game played by [[Philosophy:Brahman|Brahman]].<ref name="Schilling2008" /> The name could be pronounced like "Lilah", the name of Brown's newborn daughter. Brown was mindful of not making his name public before it had been officially accepted. He had done so with [[Astronomy:90377 Sedna|Sedna]] a year previously, and had been heavily criticized. However, no objection was raised to the Sedna name other than the breach of protocol, and no competing names were suggested for Sedna.<ref name="MPC_20040928">{{cite web
| title = M.P.C. 52733
| work = Minor Planet Circulars
| publisher = Minor Planet Center
| url = http://www.minorplanetcenter.org/iau/ECS/MPCArchive/2004/MPC_20040928.pdf
| page = 1
| year = 2004
| access-date = August 30, 2010
| archive-url = https://web.archive.org/web/20110725080207/http://www.minorplanetcenter.org/iau/ECS/MPCArchive/2004/MPC_20040928.pdf
| archive-date = July 25, 2011
| url-status = live
}}</ref>

He listed the address of his personal web page announcing the discovery as ''/~mbrown/planetlila'' and in the chaos following the [[Astronomy:Controversy over the discovery of Haumea|controversy over the discovery of Haumea]], forgot to change it. Rather than needlessly anger more of his fellow astronomers, he simply said that the webpage had been named for his daughter and dropped "Lila" from consideration.<ref name="Schilling2008" />

Brown had also speculated that ''[[Religion:Persephone|Persephone]]'', the wife of the god [[Religion:Pluto (mythology)|Pluto]], would be a good name for the object.<ref name="New Planet" /> The name had been used several times for planets in science fiction<ref name="TechRepublic2006" /> and was popular with the public, having handily won a poll conducted by ''New Scientist'' magazine.<ref name="O'Neill2005-NewScientist" /> ("Xena", despite only being a nickname, came fourth.) This choice was not possible once the object was classified as a dwarf (and thus minor) planet, because there was already a [[Astronomy:Minor planet|minor planet]] with that name, [[Astronomy:399 Persephone|399 Persephone]].<ref name="New Planet" />

The discovery team proposed ''[[Astronomy:Eris (mythology)|Eris]]'' on September 6, 2006. On September 13, 2006, this was accepted as the official name by the IAU.<ref name="caltech" /><ref name="IAU0605" /> Brown decided that, because the object had been considered a [[Astronomy:Planet|planet]] for so long, it deserved a name from [[Religion:Greek mythology|Greek]] or Roman mythology like the other planets. The asteroids had taken the vast majority of Graeco-Roman names. ''Eris'', whom Brown described as his favorite goddess, had fortunately escaped inclusion.<ref name="WGBH" /> "Eris caused strife and discord by causing quarrels among people," said Brown in 2006, "and that's what this one has done too."<ref>{{cite web |last=Sullivan |first=Andy |year=2006 |title=Xena renamed Eris in planet shuffle |url=http://www.abc.net.au/science/articles/2006/09/15/1741585.htm |access-date=January 29, 2020 |publisher={{wipe|Reuters}} |archive-date=January 28, 2020 |archive-url=https://web.archive.org/web/20200128124714/http://www.abc.net.au/science/articles/2006/09/15/1741585.htm |url-status=live }}</ref>

Planetary symbols are no longer much used in astronomy, but NASA has used the Hand of Eris, {{angbr|[[File:Eris symbol (fixed width).svg|16px|⯰]]}} (U+2BF0), for Eris.<ref>{{cite web |url= https://www.jpl.nasa.gov/infographics/what-is-a-dwarf-planet |author= JPL/NASA |date= April 22, 2015 |website= Jet Propulsion Laboratory |title= What is a Dwarf Planet? |access-date= 2021-09-24 |archive-date= December 8, 2021 |archive-url= https://web.archive.org/web/20211208181916/https://www.jpl.nasa.gov/infographics/what-is-a-dwarf-planet |url-status= live }}</ref> This is a symbol from Discordianism, a religion that worships the goddess Eris.<ref name=faulks/> Most astrologers use this symbol, while some use a symbol resembling that of Mars but with the arrow pointing downward, {{angbr|16px|⯱}} (U+2BF1).<ref name=faulks>{{cite web|url=https://www.unicode.org/L2/L2016/16173-eris-sedna.pdf|title=Eris and Sedna Symbols|last=Faulks|first=David|date=June 12, 2016|website=unicode.org|archive-url=https://archive.today/20170508160706/http://www.unicode.org/L2/L2016/16173-eris-sedna.pdf|archive-date=May 8, 2017}}</ref> Both symbols have been included in [[Unicode]].<ref>{{cite web |url=https://www.unicode.org/charts/PDF/U2B00.pdf |title=Miscellaneous Symbols and Arrows |author=<!--Not stated--> |date=1991–2021 |website=unicode.org |publisher=Unicode |access-date=6 August 2022 |archive-date=August 2, 2022 |archive-url=https://web.archive.org/web/20220802202914/https://www.unicode.org/charts/PDF/U2B00.pdf |url-status=live }}</ref>

== Classification ==
[[File:TheTransneptunians 73AU.svg|thumb|upright=1.5|Distribution of trans-Neptunian objects]]
Eris is a trans-Neptunian [[Astronomy:Dwarf planet|dwarf planet]] (plutoid).<ref name="plutoid" /> Its orbital characteristics more specifically categorize it as a [[Astronomy:Scattered disc|scattered-disk object]] (SDO), or a TNO that has been "scattered" from the [[Astronomy:Kuiper belt|Kuiper belt]] into more-distant and unusual [[Physics:Orbit|orbit]]s following gravitational interactions with [[Astronomy:Neptune|Neptune]] as the [[Astronomy:Solar System|Solar System]] was forming. Although its high orbital inclination is unusual among the known SDOs, theoretical models suggest that objects that were originally near the inner edge of the Kuiper belt were scattered into orbits with higher inclinations than objects from the outer belt.<ref name="GallardoBrunini" />

Because Eris was initially thought to be larger than [[Astronomy:Pluto|Pluto]], it was described as the "tenth planet" by [[Organization:NASA|NASA]] and in media reports of its discovery.<ref name="JPL-2005-126" /> In response to the uncertainty over its status, and because of ongoing debate over whether Pluto should be classified as a [[Astronomy:Planet|planet]], the IAU delegated a group of astronomers to develop a sufficiently precise definition of the term ''planet'' to decide the issue. This was announced as the IAU's ''[[Astronomy:IAU definition of planet|Definition of a Planet in the Solar System]],'' adopted on August 24, 2006. At this time, both Eris and Pluto were classified as ''[[Astronomy:Dwarf planet|dwarf planet]]s,'' a category distinct from the new definition of ''planet.''<ref name="IAU 2006 5&6" /> Brown has since stated his approval of this classification.<ref name="Britt2006" /> The IAU subsequently added Eris to its [[Astronomy:List of minor planets|Minor Planet Catalogue]], designating it ''(136199) Eris.''<ref name="IAUC 8747" />

== Orbit ==
thumb|The orbit of Eris (blue) compared to those of [[Saturn, [[Astronomy:Uranus|Uranus]], Neptune, and Pluto (white/gray). The arcs below the ecliptic are plotted in darker colors, and the red dot is the Sun. The diagram on the left is a polar view whereas the diagrams on the right are different views from the ecliptic.]]
thumb|Seen from Earth, Eris makes small loops in the sky through the constellation of [[Cetus (constellation)|Cetus.]]
Eris has an [[Astronomy:Orbital period|orbital period]] of 559 [[Astronomy:Julian year|years]].<ref name="AstDys" /> Its maximum possible distance from the [[Astronomy:Sun|Sun]] ([[Astronomy:Apsis|aphelion]]) is 97.5&nbsp;[[Astronomy:Astronomical unit|AU]], and its closest (perihelion) is 38&nbsp;AU.<ref name="AstDys" /> As the time of perihelion is defined at the [[Astronomy:Epoch|epoch]] chosen using an unperturbed [[Two-body problem|two-body solution]], the further the epoch is from the date of perihelion, the less accurate the result. [[Numerical integration]] is required to predict the time of perihelion accurately. Numerical integration by JPL Horizons shows that Eris came to perihelion around 1699,<ref name="Horizons1699"/> to aphelion around 1977, and will return to perihelion around December 2257.<ref name="Horizons2257"/> Unlike those of the eight planets, whose orbits all lie roughly in the same plane as the Earth's, Eris's orbit is highly [[Astronomy:Orbital inclination|inclined]]: it is tilted at an angle of about 44&nbsp;[[Degree (angle)|degrees]] to the [[Astronomy:Ecliptic|ecliptic]].<ref name="jpldata"/> When discovered, Eris and its moon were the most distant known objects in the Solar System, apart from long-period comets and [[Engineering:Space probe|space probe]]s.<ref name="New Planet" /><ref name="Peat-Heavens-Above" /> It retained this distinction until the discovery of {{mpl|2018 VG|18}} in 2018.<ref name=Carnegie2018>{{cite web |title=Discovered: The Most-Distant Solar System Object Ever Observed |url=https://carnegiescience.edu/news/discovered-most-distant-solar-system-object-ever-observed |publisher=Carnegie Science |access-date=December 18, 2018 |quote=The second-most-distant observed Solar System object is Eris, at about 96 AU. |archive-url=https://web.archive.org/web/20181217235028/https://carnegiescience.edu/news/discovered-most-distant-solar-system-object-ever-observed |archive-date=December 17, 2018 |url-status=live |date=December 17, 2018 }}</ref>

As of 2008, there were approximately forty known [[Astronomy:Trans-Neptunian object|TNOs]], most notably {{mpl|2006 SQ|372}}, {{mpl-|87269|2000 OO|67}} and {{dp|Sedna}}, that are currently closer to the Sun than Eris, even though their semimajor axis is larger than that of Eris (67.8&nbsp;AU).<ref name="MPC" />

[[File:Eris800yearsb.gif|thumb|left|The distances of Eris and Pluto from the Sun in the next 1,000 years]]

The Eridian orbit is highly [[Astronomy:Orbital eccentricity|eccentric]], and brings Eris to within 37.9&nbsp;AU of the Sun, a typical perihelion for scattered objects.<ref name="tjl2000">{{cite journal |first1=Chadwick A. |last1=Trujillo |first2=David C. |last2=Jewitt |first3=Jane X. |last3=Luu |s2cid=8240136 |title=Population of the Scattered Kuiper Belt |journal=The Astrophysical Journal |volume=529 |pages=L103–L106 |date=February 1, 2000 |url=http://www2.ess.ucla.edu/~jewitt/papers/SKBO/tjl2000.pdf  |access-date=July 2, 2008 |doi=10.1086/312467 |pmid= 10622765 |issue= 2 |archive-url = https://web.archive.org/web/20070812095910/http://www.ifa.hawaii.edu/faculty/jewitt/papers/SKBO/tjl2000.pdf |archive-date = August 12, 2007 |bibcode=2000ApJ...529L.103T|arxiv = astro-ph/9912428 |citeseerx=10.1.1.338.2682 }}</ref>  This is within the orbit of Pluto, but still safe from direct interaction with Neptune (~37 AU).<ref>{{cite journal|title=Dynamical classification of trans-neptunian objects: Probing their origin, evolution, and interrelation|author=Patryk Sofia Lykawka, Tadashi Mukai|url=https://www.sciencedirect.com/science/article/abs/pii/S001910350700036X|journal=Icarus|volume=189|issue=1|date=July 2007|pages=213–232|doi=10.1016/j.icarus.2007.01.001|bibcode=2007Icar..189..213L|access-date=January 29, 2020|archive-date=January 29, 2020|archive-url=https://web.archive.org/web/20200129185546/https://www.sciencedirect.com/science/article/abs/pii/S001910350700036X|url-status=live}}</ref> Pluto, on the other hand, like other [[Astronomy:Plutino|plutino]]s, follows a less inclined and less eccentric orbit and, protected by orbital resonance, can cross Neptune's orbit.<ref>{{cite web|title=The Plutinos|url=http://www2.ess.ucla.edu/~jewitt/kb/plutino.html|author=David Jewitt|work=UCLA|access-date=January 29, 2020|archive-date=April 19, 2007|archive-url=https://web.archive.org/web/20070419234021/http://www.ifa.hawaii.edu/~jewitt/kb/plutino.html|url-status=live}}</ref> In about 800&nbsp;years, Eris will be closer to the Sun than Pluto for some time (see the graph at the left).

As of 2007, Eris has an [[Astronomy:Apparent magnitude|apparent magnitude]] of 18.7, making it bright enough to be detectable to some amateur [[Astronomy:Telescope|telescope]]s.<ref>{{cite journal|title= Observations of dwarf planet (136199) Eris and other large TNOs on Lulin Observatory|author1= H.-W.Lin|author2= Y.-L.Wu|author3= W.-H.Ip|journal= Advances in Space Research|volume= 40|issue= 2|year= 2007|pages= 238–243|doi= 10.1016/j.asr.2007.06.009|bibcode= 2007AdSpR..40..238L|url= https://www.sciencedirect.com/science/article/pii/S0273117707006242|access-date= January 29, 2020|archive-date= January 29, 2020|archive-url= https://web.archive.org/web/20200129215446/https://www.sciencedirect.com/science/article/pii/S0273117707006242|url-status= live}}</ref> A {{convert|200|mm|in|adj=on|sp=us}} telescope with a [[Engineering:Charge-coupled device|CCD]] can detect Eris under favorable conditions.<ref group="lower-alpha">For an example of an amateur image of Eris, see [http://www.moonglow.net/ccd/pictures/pc/index.html#tnos Fred Bruenjes' Astronomy] {{Webarchive|url=https://web.archive.org/web/20051102025526/http://moonglow.net/ccd/pictures/pc/index.html#tnos |date=November 2, 2005 }}</ref> The reason it had not been noticed until now is its steep orbital inclination; searches for large outer Solar System objects tend to concentrate on the ecliptic plane, where most bodies are found.<ref>{{cite episode|title=Bye-Bye Planet Pluto|series=Horizon|network=BBC|date= June 22, 2006}}</ref>

Because of the high inclination of its orbit, Eris passes through only a few constellations of the traditional [[Astronomy:Zodiac|Zodiac]]; it is now in the constellation Cetus. It was in [[Astronomy:Sculptor (constellation)|Sculptor]] from 1876 until 1929 and [[Astronomy:Phoenix (constellation)|Phoenix]] from roughly 1840 until 1875. In 2036 it will enter [[Astronomy:Pisces (constellation)|Pisces]] and stay there until 2065, when it will enter [[Astronomy:Aries (constellation)|Aries]].<ref name="horizons" /> It will then move into the [[Celestial sphere|northern sky]], entering [[Astronomy:Perseus (constellation)|Perseus]] in 2128 and [[Astronomy:Camelopardalis|Camelopardalis]] (where it will reach its northernmost [[Declination|declination]]) in 2173.

== Size, mass and density ==
{{multiple image
 | align     = left
 | direction = vertical
 | image1    = Eris, Earth & Moon size comparison.png
 | width1    = 300
 | caption1  = Size comparison: Eris (''lower left'') with the Moon and Earth (''top and right'')
 | image2    = The occultation of the dwarf planet Eris in November 2010.jpg
 | width2    = 300
 | caption2  = Illustration of the stellar occultation by Eris in November 2010. The resulting occultation [[Astronomy:Chord|chords]] project a circular silhouette for Eris, giving a spherical diameter of {{cvt|2326|km|mi}}
}}
{| class="wikitable plainrowheaders floatright"
|+ Size estimates
! scope="col" | Year !! Radius<br>km !! Source
|-
! scope="row" | 2005
| 1,199<!--1198.5--><!--Which is, 1199 _km_. If the accuracy was ±100km, it would imply it should only really be quoted to the nearest 10km, or 1200 km. This is spurious accuracy. Note how spitzer uses 1300.--><ref name="hst1" />
| ''[[Astronomy:Hubble Space Telescope|Hubble]]''
|-
! scope="row" | 2007
| 1,300<ref name="spitzer" />
| [[Astronomy:Spitzer Space Telescope|Spitzer]]
|-
! scope="row" | 2011
| 1,163<ref name="sicardy" />
| [[Astronomy:Asteroid occultation|Occultation]]
|}
{{image frame
|content={{Graph:Chart
   | width=400
   | height=200
   | type=rect
   | x=Triton,Eris,Pluto,Haumea,Titania,Makemake,Oberon,Rhea,Iapetus,Gonggong,Charon,Quaoar,Ceres,Orcus
   | y1=21.39,16.6,13.03,4.01,3.40,3.1,3.08,2.307,1.806,1.75,1.59,1.4,0.94,0.61
   | showValues=format:.1f, offset:1
   | xAxisAngle=45
}}
|width=440
|caption=The mass of Eris compared to other dwarf planets ({{dp|Pluto}}, {{dp|Haumea}}, {{dp|Makemake}}, {{dp|Gonggong}}, {{dp|Quaoar}}, {{dp|Orcus}}, {{dp|Ceres}}), [[Astronomy:Charon (moon)|Charon]], and the icy moons [[Astronomy:Titania (moon)|Titania]] (Uranus III), [[Astronomy:Oberon (moon)|Oberon]] (Uranus IV), [[Astronomy:Rhea (moon)|Rhea]] (Saturn V), Iapetus (Saturn VIII) and [[Astronomy:Triton (moon)|Triton]] (Neptune I). The unit of mass is {{e|21}} kg.
|border=no
}}

In November 2010, Eris was the subject of one of the most distant stellar occultations yet from Earth.<ref name="Beatty2010-NewScientist" /> Preliminary data from this event cast doubt on previous size estimates.<ref name="Beatty2010-NewScientist" /> The teams announced their final results from the occultation in October 2011, with an estimated diameter of {{val|2326|12|u=km}}.<ref name="sicardy" />

This makes Eris a little smaller than Pluto by area and diameter, which is {{val|2372|4|u=km}} across, although Eris is more massive. It also indicates a [[Physics:Geometric albedo|geometric albedo]] of 0.96. It is speculated that the high albedo is due to the surface ices being replenished because of temperature fluctuations as Eris's eccentric orbit takes it closer and farther from the Sun.<ref name="Brown-2003-UB313" />

The mass of Eris can be calculated with much greater precision. Based on the accepted value for Dysnomia's period at the time—15.774 days<ref name="Brown Schaller 2007" /><ref name="Brown-planetlila-moon" />—Eris is 27% more massive than Pluto. Using the 2011 occultation results, Eris has a density of {{val|2.52|0.07|u=g/cm3}},{{refn|group=lower-alpha|name=densitynote|Calculated by dividing the listed mass by the listed volume}} substantially denser than Pluto, and thus must be composed largely of rocky materials.<ref name="sicardy" />

Models of internal heating via [[Physics:Radioactive decay|radioactive decay]] suggest that Eris could have an subsurface ocean of liquid water at the mantle–core boundary.<ref name="Hussman2006">{{cite journal| doi = 10.1016/j.icarus.2006.06.005| last1 = Hussmann| first1 = Hauke| last2 = Sohl| first2 = Frank| last3 = Spohn| first3 = Tilman| date = November 2006| title = Subsurface oceans and deep interiors of medium-sized outer planet satellites and large trans-neptunian objects| journal = Icarus| volume = 185| issue = 1| pages = 258–273| url = https://www.researchgate.net/publication/225019299| bibcode = 2006Icar..185..258H| ref = {{sfnRef|Hussmann Sohl et al.|2006}}| access-date = December 2, 2017| archive-url = https://web.archive.org/web/20150831232202/http://www.researchgate.net/profile/Tilman_Spohn/publication/225019299_Subsurface_Oceans_and_Deep_Interiors_of_Medium-Sized_Outer_Planet_Satellites_and_Large_Trans-Neptunian_Objects/links/55018a3a0cf24cee39f7b952.pdf| archive-date = August 31, 2015| url-status = live}}</ref> [[Astronomy:Tidal heating|Tidal heating]] of Eris by its moon Dysnomia may additionally contribute to the preservation of its possible subsurface ocean.<ref name="Saxena2018"/>

In July 2015, after nearly a decade of Eris being thought to be the ninth-largest known object to directly orbit the Sun, close-up imagery from the ''[[Astronomy:New Horizons|New Horizons]]'' mission determined the volume of [[Astronomy:Pluto|Pluto]] to be slightly larger than that of Eris.<ref name="NBC2015-Pluto-n391321" /> Eris is now understood to be the tenth-largest known object to directly orbit the Sun by volume, but remains the ninth-largest by mass.

== Surface and atmosphere ==
[[File:2003 UB313 near-infrared spectrum.png|thumb|The infrared spectrum of Eris, compared to that of Pluto, shows the marked similarities between the two bodies. Arrows denote methane absorption lines.]]

The discovery team followed up their initial identification of Eris with [[Physics:Astronomical spectroscopy|spectroscopic]] observations made at the 8&nbsp;m Gemini North Telescope in Hawaii on January 25, 2005. Infrared light from the object revealed the presence of [[Chemistry:Methane|methane]] ice, indicating that the surface may be similar to that of Pluto, which at the time was the only [[Astronomy:Trans-Neptunian object|TNO]] known to have surface methane, and of Neptune's moon [[Astronomy:Triton (moon)|Triton]], which also has methane on its surface.<ref name="gemini.edu.tenth" /> In 2022, near-infrared spectroscopy of Eris by the [[Astronomy:James Webb Space Telescope|James Webb Space Telescope]] (JWST) revealed the presence of [[Physics:Deuterium|deuterated]] methane ice on its surface, at abundances lower than those in Jupiter-family comets like 67P/Churyumov–Gerasimenko.<ref name="Grundy2023"/> Eris's comparatively low deuterium abundance suggests that its methane is not primordial and instead may have been produced from subsurface geochemical processes.<ref name="Grundy2023"/> Substantial quantities of nitrogen ice on Eris was also detected by the JWST, and it is presumed to have originated from subsurface processes similar to Eris's likely non-primordial methane.<ref name="Grundy2023"/> The abundance of nitrogen ice on Eris is estimated to be one-third of that of methane by volume.<ref name="Grundy2023"/>

Unlike the somewhat reddish and variegated surfaces of Pluto and Triton, the surface of Eris appears almost white and uniform.<ref name="New Planet" /> Pluto's reddish color is thought to be due to deposits of [[Astronomy:Tholin|tholin]]s on its surface, and where these deposits darken the surface, the lower albedo leads to higher temperatures and the evaporation of methane deposits. In contrast, Eris is far enough from the Sun that methane can [[Physics:Condensation|condense]] onto its surface even where the albedo is low. The condensation of methane uniformly over the surface reduces any albedo contrasts and would cover up any deposits of red tholins.<ref name="Brown-AJ2005-635" /> This methane sublimation and condensation cycle could produce [[Earth:Penitente (snow formation)|bladed terrain]] on Eris, similar to those on Pluto.<ref name="Hofgartner2019"/><ref name="Grundy2023"/> Alternatively, Eris's surface could be refreshed through radiogenic [[Astronomy:Convection|convection]] of a global methane and nitrogen ice glacier, similar to Pluto's [[Astronomy:Sputnik Planitia|Sputnik Planitia]].<ref name="Grundy2017"/><ref name="Grundy2023"/> Spectroscopic observations by the JWST support the idea that Eris's surface is continually refreshing, as no signs of [[Chemistry:Ethane|ethane]], a byproduct of [[Physics:Radiolysis|radiolyzed]] methane, were detected on Eris's surface.<ref name="Grundy2023"/> 

Due to the distant and eccentric orbit of Eris, its surface temperature is estimated to vary from about {{convert|30|to|56|K|C F}}.<ref name="New Planet" /> Even though Eris can be up to three times farther from the Sun than Pluto, it approaches close enough that some of the ices on the surface might warm enough to sublime to form an [[Astronomy:Atmosphere|atmosphere]]. Because methane and nitrogen are both highly [[Chemistry:Volatility|volatile]], their presence shows either that Eris has always resided in the distant reaches of the Solar System, where it is cold enough for methane and nitrogen ice to persist, or that the celestial body has an internal source to replenish gas that escapes from its atmosphere.<ref name="Hofgartner2019"/> This contrasts with observations of another discovered TNO, {{dp|Haumea}}, which reveal the presence of [[Chemistry:Water|water]] ice but not methane.<ref name="Licandro-AA2006-458" />

== Rotation ==
Eris displays very little variation in brightness as it rotates due to its uniform surface, making measurement of its [[Rotation period|rotation period]] difficult.<ref name="Duffard2008"/><ref name="Szakats2022"/> Precise long-term monitoring of Eris's brightness indicates that it is tidally locked to its moon Dysnomia, with a rotation period [[Astronomy:Synchronous orbit|synchronous]] with the moon's orbital period of 15.78 [[Astronomy:Earth|Earth]] days.<ref name="Szakats2022" /> Dysnomia is also tidally locked to Eris, which makes the Eris–Dysnomia system the second known case of double-synchronous rotation, after [[Astronomy:Pluto|Pluto]] and [[Astronomy:Charon (moon)|Charon]]. Previous measurements of Eris's rotation period obtained highly uncertain values ranging tens of hours to several days due to insufficient long-term coverage of Eris's rotation.<ref name="Duffard2008" /><ref name="Roe2008"/><ref name="Holler2020"/> The [[Astronomy:Axial tilt|axial tilt]] of Eris has not been measured,<ref name="Holler2021" /> but it can be reasonably assumed that it is the same as Dysnomia's orbital inclination, which would be about 78&nbsp;degrees with respect to the ecliptic.<ref name="Holler2018" /> If this were the case, most of Eris's northern hemisphere would be illuminated by sunlight, with 30% of the hemisphere experiencing constant illumination in 2018.<ref name="Holler2018" />

== Satellite ==
{{Main | Astronomy:Dysnomia (moon) }}
[[File:ESO-L. Calçada - Eso1142c (by).jpg|thumb|alt=Dysnomia|Artist's conception of Eris and its dark moon Dysnomia]]
In 2005, the [[Astronomy:Adaptive optics|adaptive optics]] team at the Keck telescopes in Hawaii carried out observations of the four brightest [[Astronomy:Trans-Neptunian object|TNOs]] (Pluto, {{dp|Makemake}}, {{dp|Haumea}}, and Eris), using the newly commissioned [[Physics:Laser guide star|laser guide star]] adaptive optics system.<ref name="Brown Van Dam et al. 2006" /> Images taken on September 10 revealed a [[Astronomy:Natural satellite|moon]] in orbit around Eris. In keeping with the "Xena" nickname already in use for Eris, Brown's team nicknamed the moon "Gabrielle", after the television warrior princess's sidekick. When Eris received its official name from the IAU, the moon received the name ''[[Astronomy:Dysnomia (moon)|Dysnomia]],'' after the [[Astronomy:Dysnomia (deity)|Greek goddess of lawlessness]] who was Eris's daughter. Brown says he picked it for similarity to his wife's name, Diane. The name also retains an oblique reference to Eris's old informal name ''Xena'', portrayed on television by Lucy Lawless, though the connection was unintentional.<ref name="Tytell-ST2006" />

{| class="wikitable"
|+Eridian system
!Name
!Diameter<br>(km)
!Semi-major axis<br>(km)
!Mass<br>(× 10<sup>22</sup>&nbsp;kg)
!Discovery date
|-
|Eris
|{{val|2326|12}}<ref name="sicardy" />
|
|{{val|1.638|0.014}}{{efn|name=erismass|The mass of Eris by itself is the difference between the mass of the system ({{val|1.6466|0.0085|e=22|u=kg}})<ref name="Holler2021"/> and mass of Dysnomia by itself ({{val|8.2|5.7|e=19|u=kg}}).<ref name="Brown2023" /> }}
|January 5, 2005
|-
|Dysnomia
|{{val|615|60|50}}<ref name=Brown2023/>
|{{val|37273|64}}<ref name="Holler2021"/>
|{{val|.008|.006}}<ref name="Brown2023" />
|September 10, 2005<ref name="Brown Van Dam et al. 2006" />
|}

== Exploration ==
Eris was observed from afar by the outbound ''[[Astronomy:New Horizons|New Horizons]]'' spacecraft in May 2020, as part of its extended mission following its successful Pluto [[Engineering:Flyby (spaceflight)|flyby]] in 2015.<ref name="Verbiscer2022"/> Although Eris was farther from ''New Horizons'' (112&nbsp;AU) than it was from Earth (96&nbsp;AU), the spacecraft's unique vantage point inside the Kuiper belt permitted observations of Eris at high [[Physics:Phase angle|phase angles]] that are otherwise unobtainable from Earth, enabling the determination of the light scattering properties and [[Physics:Phase curve|phase curve]] behavior of the Eridian surface.<ref name="Verbiscer2022"/> 

In the 2010s, there were multiple studies for follow-on missions to explore the Kuiper belt, among which Eris was evaluated as a candidate.<ref>{{Cite news|url=https://www.astrobio.net/also-in-news/swri-team-makes-breakthroughs-studying-pluto-orbiter-mission/|title=SwRI team makes breakthroughs studying Pluto orbiter mission |date=October 25, 2018|work=Astrobiology Magazine|access-date=October 27, 2018|language=en-US |archive-url=https://web.archive.org/web/20181028035159/https://www.astrobio.net/also-in-news/swri-team-makes-breakthroughs-studying-pluto-orbiter-mission/ |archive-date=2018-10-28 |url-status=usurped}}</ref> It was calculated that a flyby mission to Eris would take 24.66 years using a Jupiter gravity-assist, based on launch dates of April 3, 2032, or April 7, 2044. Eris would be 92.03 or 90.19 AU from the Sun when the spacecraft arrives.<ref name="McGranaghan" />

== See also ==
* [[Astronomy:Clearing the neighbourhood|Clearing the neighbourhood]]
* [[Astronomy:Planet#Objects formerly considered planets|Former classification of planets]]
* List of Solar System objects most distant from the Sun
* [[Astronomy:List of trans-Neptunian objects|List of trans-Neptunian objects]]
* [[Astronomy:Mesoplanet|Mesoplanet]]

== Explanatory notes ==
{{Reflist|group=lower-alpha}}
<!--Note F is not linked to anywhere in the page. "If the object is in pole-on position, the side facing the Sun (and the observer) gets hotter producing stronger emissions thus resulting in overestimation of the diameter using the thermal method."-->

== References ==

{{Reflist
| refs =

<ref name="discovery">{{cite web
| date = May 1, 2007
| url = http://www.minorplanetcenter.org/iau/lists/NumberedMPs.html
| title = Discovery Circumstances: Numbered Minor Planets
| publisher = IAU: Minor Planet Center
| access-date = May 5, 2007
| archive-url = https://web.archive.org/web/20160504211412/http://www.minorplanetcenter.org/iau/lists/NumberedMPs.html
| archive-date = May 4, 2016
| url-status = live
}}</ref>

<ref name="New Planet">{{cite web
| title = The discovery of 2003 UB313 Eris, the largest known dwarf planet
| url = http://www.gps.caltech.edu/~mbrown/planetlila/
| last = Brown
| first = Mike
| publisher = California Institute of Technology, Department of Geological Sciences
| date = 2006
| access-date = May 3, 2007
| archive-url = https://web.archive.org/web/20110719163702/http://www.gps.caltech.edu/~mbrown/planetlila/
| archive-date = July 19, 2011
| url-status = live
}}</ref>

<ref name="jpldata">{{cite web
| type = December 14, 2019, solution date
| title = JPL Small-Body Database Browser: 136199 Eris (2003 UB313)
| url = https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=136199
| access-date = February 20, 2020
| archive-url = https://web.archive.org/web/20160412115622/http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=136199
| archive-date = April 12, 2016
| url-status = live
}}</ref>

<ref name="MPC">{{cite web
| title = List Of Centaurs and Scattered-Disk Objects
| publisher = Minor Planet Center
| url = http://www.minorplanetcenter.org/iau/lists/Centaurs.html
| access-date = September 10, 2008
| archive-url = https://web.archive.org/web/20110725075304/http://www.minorplanetcenter.org/iau/lists/Centaurs.html
| archive-date = July 25, 2011
| url-status = live
}}</ref>

<ref name="Buie2007">{{cite web
| last = Buie
| first = Marc
| date = November 6, 2007
| title = Orbit Fit and Astrometric record for 136199
| publisher = [[Astronomy:Deep Ecliptic Survey|Deep Ecliptic Survey]]
| url = http://www.boulder.swri.edu/~buie/kbo/astrom/136199.html
| access-date = December 8, 2007
| archive-url = https://web.archive.org/web/20120730162307/http://www.boulder.swri.edu/~buie/kbo/astrom/136199.html
| archive-date = July 30, 2012
| url-status = live
}}</ref>

<ref name="sicardy">{{cite journal
| title = Size, density, albedo and atmosphere limit of dwarf planet Eris from a stellar occultation
| journal = European Planetary Science Congress Abstracts
| volume = 6
| date = 2011
| url = http://meetingorganizer.copernicus.org/EPSC-DPS2011/EPSC-DPS2011-137-8.pdf
| access-date = September 14, 2011
| bibcode = 2011epsc.conf..137S
| last1 = Sicardy
| first1 = B.
| last2 = Ortiz
| first2 = J. L.
| last3 = Assafin
| first3 = M.
| last4 = Jehin
| first4 = E.
| last5 = Maury
| first5 = A.
| last6 = Lellouch
| first6 = E.
| last7 = Gil-Hutton
| first7 = R.
| last8 = Braga-Ribas
| first8 = F.
| last9 = Colas
| first9 = F.
| page = 137
| author10 = Widemann
| archive-url = https://web.archive.org/web/20111018043926/http://meetingorganizer.copernicus.org/EPSC-DPS2011/EPSC-DPS2011-137-8.pdf
| archive-date = October 18, 2011
| url-status = live
}}</ref>

<ref name="Beatty2010-NewScientist">{{cite web
| last = Beatty
| first = Kelly
| title = Former 'tenth planet' may be smaller than Pluto
| publisher = Sky and Telescope
| work = NewScientist.com
| date = November 2010
| url = https://www.newscientist.com/article/dn19697-former-tenth-planet-may-be-smaller-than-pluto.html
| access-date = October 17, 2011
| archive-url = https://web.archive.org/web/20120223213839/http://www.newscientist.com/article/dn19697-former-tenth-planet-may-be-smaller-than-pluto.html
| archive-date = February 23, 2012
| url-status = live
}}</ref>

<ref name="Brown Schaller 2007">{{cite journal| doi = 10.1126/science.1139415| last1 = Brown| first1 = Michael E.|  last2 = Schaller| first2 = Emily L.| s2cid = 21468196| date = June 15, 2007| title = The Mass of Dwarf Planet Eris| journal = Science| volume = 316| issue = 5831| page = 1585| pmid = 17569855| bibcode = 2007Sci...316.1585B| url = http://hubblesite.org/pubinfo/pdf/2007/24/pdf.pdf| access-date = September 27, 2015| archive-url = https://web.archive.org/web/20160304053122/http://hubblesite.org/pubinfo/pdf/2007/24/pdf.pdf| archive-date = March 4, 2016}} <!-- {{sfn|Brown Schaller|2007}} --></ref>

<ref name="Snodgrass et al. 2010">
{{cite journal| doi = 10.1051/0004-6361/200913031| last1 = Snodgrass| first1 = C.| last2 = Carry| first2 = B.| last3 = Dumas| first3 = C.| last4 = Hainaut| first4 = O.| s2cid = 62880843| title = Characterisation of candidate members of (136108) Haumea's family| journal = Astronomy and Astrophysics| volume = 511| pages = A72| date = February 2010| arxiv = 0912.3171| bibcode = 2010A&A...511A..72S}} <!-- {{sfn|Snodgrass|Carry|Dumas|Hainaut|2010}} ...et al. it... -->
</ref>

<ref name="AstDys">{{cite web
| title = AstDys (136199) Eris Ephemerides
| publisher = Department of Mathematics, University of Pisa, Italy
| url = https://newton.spacedys.com/astdys/index.php?pc=1.1.3.0&n=Eris
| access-date = February 28, 2016
| archive-date = June 12, 2021
| archive-url = https://web.archive.org/web/20210612104326/https://newton.spacedys.com/astdys/index.php?pc=1.1.3.0&n=Eris
| url-status = live
}}</ref>

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{{cite journal| doi = 10.1038/nature04494| last1 = Bertoldi | first1 = F.| last2 = Altenhoff | first2 = W.| last3 = Weiss | first3 = A.| last4 = Menten | first4 = K. M.| last5 = Thum | first5 = C.| date = February 2, 2006| title = The trans-Neptunian object {{mp|UB|313}} is larger than Pluto| journal = Nature| volume = 439| issue = 7076| pages = 563–564| pmid = 16452973| bibcode = 2006Natur.439..563B| ref = {{sfnRef|Bertoldi Altenhoff et al.|2006}}
}}  {{sfn|Bertoldi Altenhoff et al.|2006}}
</ref> -->

<ref name="070614_eris_mass">{{cite web
| title = Dwarf Planet Outweighs Pluto
| url = http://www.space.com/scienceastronomy/070614_eris_mass.html
| work = space.com
| date = 2007
| access-date = June 14, 2007
| archive-url = https://web.archive.org/web/20070617175259/http://www.space.com/scienceastronomy/070614_eris_mass.html
| archive-date = June 17, 2007
| url-status = live
}}</ref>

<ref name="NASA Pluto larger 2015">{{cite web
| title = How Big Is Pluto? New Horizons Settles Decades-Long Debate
| url = http://www.nasa.gov/feature/how-big-is-pluto-new-horizons-settles-decades-long-debate
| work = www.nasa.gov
| date = 2015
| access-date = July 14, 2015
| archive-url = https://web.archive.org/web/20170701005734/https://www.nasa.gov/feature/how-big-is-pluto-new-horizons-settles-decades-long-debate/
| archive-date = July 1, 2017
| url-status = live
}}</ref>

<ref name="IAUPressRelease2006">
{{cite press release|publisher=IAU |date=August 16, 2006 |title=The IAU draft definition of "planet" and "plutons" |url=http://www.iau2006.org/mirror/www.iau.org/iau0601/iau0601_release.html |access-date=August 16, 2006 |archive-url=https://web.archive.org/web/20060820075858/http://www.iau2006.org/mirror/www.iau.org/iau0601/iau0601_release.html |archive-date=August 20, 2006 }}
</ref>

<ref name="Brown2010-occult">{{cite web
| last = Brown
| first = Mike
| date = 2010
| title = The shadowy hand of Eris
| publisher = Mike Brown's Planets
| url = http://www.mikebrownsplanets.com/2010/11/shadowy-hand-of-eris.html
| access-date = November 7, 2010
| archive-url = https://web.archive.org/web/20101111112050/http://www.mikebrownsplanets.com/2010/11/shadowy-hand-of-eris.html
| archive-date = November 11, 2010
| url-status = live
}}</ref>

<ref name="Brown2010-Plutosize">{{cite web
| last = Brown
| first = Mike
| date = November 22, 2010
| title = How big is Pluto, anyway?
| publisher = Mike Brown's Planets
| url = http://www.mikebrownsplanets.com/2010/11/how-big-is-pluto-anyway.html
| access-date = November 23, 2010
| archive-url = https://web.archive.org/web/20110721064541/http://www.mikebrownsplanets.com/2010/11/how-big-is-pluto-anyway.html
| archive-date = July 21, 2011
| url-status = live
}} [http://tech.groups.yahoo.com/group/mpml/message/24568 (Franck Marchis on 2010-11-08)]{{dead link|date=December 2023|bot=medic}}{{cbignore|bot=medic}}</ref>

<ref name="MaughJohnson">{{cite news
| title = His Stellar Discovery Is Eclipsed
| author1 = Thomas H. Maugh II
| author2 = John Johnson Jr.
| work = Los Angeles Times
| url = http://articles.latimes.com/2005/oct/16/local/me-planet16
| access-date = July 14, 2008
| date = October 16, 2005
| archive-url = https://web.archive.org/web/20121012075527/http://articles.latimes.com/2005/oct/16/local/me-planet16
| archive-date = October 12, 2012
| url-status = live
}}</ref>

<ref name="plutoid">{{cite web
| url = http://www.space.com/scienceastronomy/080611-plutoid-planets.html
| title = Pluto Now Called a Plutoid
| work = Space.com
| date = June 11, 2008
| access-date = June 11, 2008
| archive-url = https://web.archive.org/web/20080612104427/http://www.space.com/scienceastronomy/080611-plutoid-planets.html
| archive-date = June 12, 2008
| url-status = live
}}</ref>

<ref name="GallardoBrunini">
{{cite journal
| title = On the origin of the High-Perihelion Scattered Disk: the role of the Kozai mechanism and mean motion resonances
|author1=Gomes R. S. |author2=Gallardo T. |author3=Fernández J. A. |author4=Brunini A. |s2cid=18066500 | journal = Celestial Mechanics and Dynamical Astronomy
| date = 2005
| volume = 91
| issue = 1–2
| pages = 109–129
| doi = 10.1007/s10569-004-4623-y
| bibcode = 2005CeMDA..91..109G
| hdl = 11336/38379
| hdl-access = free
}}
</ref>

<ref name="JPL-2005-126">{{cite web
| title = NASA-Funded Scientists Discover Tenth Planet
| url = http://www.jpl.nasa.gov/news/news.cfm?release=2005-126
| work = Jet Propulsion Laboratory
| date = 2005
| access-date = May 3, 2007
| archive-url = https://web.archive.org/web/20070514171359/http://www.jpl.nasa.gov/news/news.cfm?release=2005-126
| archive-date = May 14, 2007
| url-status = live
}}</ref>

<ref name="IAU 2006 5&6">
{{cite news
| url = http://www.iau.org/fileadmin/content/pdfs/Resolution_GA26-5-6.pdf
| archive-url = https://web.archive.org/web/20060928081931/http://www.iau.org/fileadmin/content/pdfs/Resolution_GA26-5-6.pdf
| archive-date = September 28, 2006
| title = IAU 2006 General Assembly: Resolutions 5 and 6
| date = August 24, 2006
| publisher = IAU
}}
</ref>

<ref name="Britt2006">
{{cite web
 |title       = Pluto Demoted: No Longer a Planet in Highly Controversial Definition
 |author      = Robert Roy Britt
 |url         = http://space.com/scienceastronomy/060824_planet_definition.html
 |work        = space.com
 |date        = 2006
 |access-date  = May 3, 2007
|archive-url  = https://web.archive.org/web/20101227092545/http://www.space.com/scienceastronomy/060824_planet_definition.html
 |archive-date = December 27, 2010
}}
</ref>

<ref name="IAUC 8747">
{{cite journal
 |last=Green
 |first=Daniel W. E.
 |title=(134340) Pluto, (136199) Eris, and (136199) Eris I (Dysnomia)
 |date=September 13, 2006
|journal=IAU Circular
 |volume=8747
 |pages=1
 |url=http://www.cbat.eps.harvard.edu/iauc/08700/08747.html
 |access-date=January 12, 2012
|ref={{sfnRef|IAUC 8747}}
 |archive-url=https://web.archive.org/web/20070205035336/http://www.cfa.harvard.edu/iau/special/08747.pdf
 |archive-date=February 5, 2007
|bibcode=2006IAUC.8747....1G
 }}
</ref>

<ref name="USGS-UB-313">{{cite web
 |last         = Blue
 |first        = Jennifer
 |title        = 2003 UB 313 named Eris
 |date         = September 14, 2006
|work         = USGS Astrogeology Research Program
 |url          = https://astrogeology.usgs.gov/HotTopics/index.php?/archives/211-2003-UB313-named-Eris.html
 |access-date   = January 3, 2007
|archive-url  = https://web.archive.org/web/20061018120634/http://astrogeology.usgs.gov/HotTopics/index.php?%2Farchives%2F211-2003-UB313-named-Eris.html
 |archive-date = October 18, 2006
}}</ref>

<ref name="IAU-2003-UB313">
{{cite web
| title = International Astronomical Association homepage
| url = http://www.iau.org/IAU/FAQ/2003_UB313.html/
| access-date = January 5, 2007
| archive-url = https://web.archive.org/web/20070930155414/http://www.iau.org/IAU/FAQ/2003_UB313.html/
| archive-date = September 30, 2007
}}
</ref>

<ref name="AAS-XenaGabrielle">{{cite web
| title = Xena and Gabrielle
| date = January 2006
| work = Status
| url = http://www.aas.org/cswa/status/Status_Jan06.pdf
| access-date = May 3, 2007
| archive-url = https://web.archive.org/web/20120314161828/http://www.aas.org/cswa/status/Status_Jan06.pdf
| archive-date = March 14, 2012
}}</ref>

<ref name="WGBH">
{{cite web
 |last        = Brown
 |first       = Mike
 |date        = 2007
 |title       = Lowell Lectures in Astronomy
 |work        = WGBH
 |url         = http://forum.wgbh.org/content/forum/3710-2007_04_11.mp3
 |access-date  = July 13, 2008
|archive-url  = https://web.archive.org/web/20080716035615/http://forum.wgbh.org/content/forum/3710-2007_04_11.mp3
 |archive-date = July 16, 2008
}}
</ref>

<ref name="Schilling2008">
{{cite book
| last = Schilling
| first = Govert
| date = 2008
| title = The Hunt For Planet X
| publisher = Springer
| page = 214
| isbn = 978-0-387-77804-4
}}
</ref>

<ref name="TechRepublic2006">{{cite web
| title = Planet X Marks the Spot
| work = TechRepublic
| date = 2006
| url = http://www.sunflower-astronomy.com/KCKCC_Docs/NewsArticles/Geek_Trivia_Planet_X_marks_the_spot.pdf
| access-date = July 13, 2008
| archive-url = https://web.archive.org/web/20080910074246/http://www.sunflower-astronomy.com/KCKCC_Docs/NewsArticles/Geek_Trivia_Planet_X_marks_the_spot.pdf
| archive-date = September 10, 2008
| url-status = live
}}</ref>

<ref name="O'Neill2005-NewScientist">{{cite web
| last = O'Neill
| first = Sean
| date = 2005
| title = Your top 10 names for the tenth planet
| work = NewScientist
| url = https://www.newscientist.com/article.ns?id=dn7811
| access-date = June 28, 2008
| archive-url = https://web.archive.org/web/20080501025106/http://www.newscientist.com/article.ns?id=dn7811
| archive-date = May 1, 2008
| url-status = live
}}</ref>

<ref name="caltech">{{cite web
| title = The Discovery of Eris, the Largest Known Dwarf Planet
| publisher = California Institute of Technology, Department of Geological Sciences
| url = http://www.gps.caltech.edu/~mbrown/planetlila/
| access-date = January 5, 2007
| archive-url = https://web.archive.org/web/20110719163702/http://www.gps.caltech.edu/~mbrown/planetlila/
| archive-date = July 19, 2011
| url-status = live
}}</ref>

<ref name="IAU0605">
{{cite web
 |title       = IAU0605: IAU Names Dwarf Planet Eris
 |date        = September 14, 2006
|work        = International Astronomical Union News
 |url         = http://www.iau.org/iau0605_Eris.409.0.html
 |access-date  = January 5, 2007
|archive-url  = https://web.archive.org/web/20070104194022/http://www.iau.org/iau0605_Eris.409.0.html
 |archive-date = January 4, 2007
}}
</ref>

<ref name="Horizons1699">{{cite web
  |title=Horizons Batch for 136199 Eris on 1699-Jul-22
  |publisher=[[Astronomy:JPL Horizons On-Line Ephemeris System|JPL Horizons]]
  |type=Perihelion occurs when rdot flips from negative to positive
  |url=https://ssd.jpl.nasa.gov/api/horizons.api?format=text&COMMAND=%27136199%27&START_TIME=%271699-Jul-01%27&STOP_TIME=%271699-Jul-31%27&STEP_SIZE=%271%20day%27&QUANTITIES=%2719%27
  |accessdate=2023-08-27
  |archive-date=August 28, 2023
  |archive-url=https://web.archive.org/web/20230828091850/https://ssd.jpl.nasa.gov/api/horizons.api?format=text&COMMAND=%27136199%27&START_TIME=%271699-Jul-01%27&STOP_TIME=%271699-Jul-31%27&STEP_SIZE=%271%20day%27&QUANTITIES=%2719%27
  |url-status=live
  }} (JPL#84/Soln.date: 2023-Aug-22)</ref>

<ref name="Horizons2257">{{cite web
  |title=Horizons Batch for 136199 Eris on 2257-Dec-01
  |publisher=[[Astronomy:JPL Horizons On-Line Ephemeris System|JPL Horizons]]
  |type=Perihelion occurs when rdot flips from negative to positive
  |url=https://ssd.jpl.nasa.gov/api/horizons.api?format=text&COMMAND=%27136199%27&START_TIME=%272257-Nov-29%27&STOP_TIME=%272257-Dec-04%27&STEP_SIZE=%273%20hours%27&QUANTITIES=%2719%27
  |archive-url=https://web.archive.org/web/20220904230807/https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%27Eris%27&START_TIME=%272257-11-28%27&STOP_TIME=%272257-12-17%27&STEP_SIZE=%273%20hours%27&QUANTITIES=%2719%27
  |archive-date=2022-09-04
  |url-status=live
  |accessdate=2023-08-27}} (JPL#84/Soln.date: 2023-Aug-22)</ref>

<ref name="horizons">{{cite web
  |title = Horizons Eris
  |url = https://ssd.jpl.nasa.gov/horizons/app.html#/
  |work = [[Astronomy:JPL Horizons On-Line Ephemeris System|JPL Horizons]]
  |access-date = September 13, 2021
  |archive-date = March 28, 2007
  |archive-url = https://web.archive.org/web/20070328180634/http://ssd.jpl.nasa.gov/?horizons#/
  |url-status = live
  }}</ref>

<ref name="Peat-Heavens-Above">{{cite web
| last = Peat
| first = Chris
| title = Spacecraft escaping the Solar System
| publisher = Heavens-Above
| url = http://www.heavens-above.com/SolarEscape.aspx
| access-date = January 25, 2008
| archive-url = https://web.archive.org/web/20180511013456/http://www.heavens-above.com/SolarEscape.aspx
| archive-date = May 11, 2018
| url-status = live
}}</ref>

<ref name="hst1">{{cite web
| title = Hubble Finds 'Tenth Planet' Slightly Larger Than Pluto
| date = April 11, 2006
| publisher = NASA
| url = http://www.nasa.gov/mission_pages/hubble/hst_xena_20060410.html
| access-date = August 29, 2008
| archive-url = https://web.archive.org/web/20080829214424/http://www.nasa.gov/mission_pages/hubble/hst_xena_20060410.html
| archive-date = August 29, 2008
| url-status = live
}}</ref>

<ref name="spitzer">
{{cite book
|author1=John Stansberry |author2=Will Grundy |author3=Mike Brown |author4=John Spencer |author5=David Trilling |author6=Dale Cruikshank |author7=Jean-Luc Margot | date = 2007
| title = Physical Properties of Kuiper Belt and Centaur Objects: Constraints from Spitzer Space Telescope
| arxiv = astro-ph/0702538
|bibcode=2008ssbn.book..161S }}
</ref>

<ref name="Brown-2003-UB313">{{cite journal
| title = Direct measurement of the size of 2003 UB313 from the Hubble Space Telescope
| author1 = M. E. Brown
| author2 = E.L. Schaller
| author3 = H.G. Roe
| author4 = D. L. Rabinowitz
| author5 = C. A. Trujillo
| s2cid = 16487075
| journal = The Astrophysical Journal
| date = 2006
| volume = 643
| issue = 2
| pages = L61–L63
| doi = 10.1086/504843
| url = http://www.gps.caltech.edu/~mbrown/papers/ps/xsize.pdf
| bibcode = 2006ApJ...643L..61B
| arxiv = astro-ph/0604245
| citeseerx = 10.1.1.256.601
| access-date = April 11, 2006
| archive-url = https://web.archive.org/web/20080910103928/http://www.gps.caltech.edu/~mbrown/papers/ps/xsize.pdf
| archive-date = September 10, 2008
| url-status = live
}}</ref>

<ref name="Brown-planetlila-moon">{{cite web
| last = Brown
| first = Mike
| date = 2007
| title = Dysnomia, the moon of Eris
| work = Caltech
| url = http://www.gps.caltech.edu/~mbrown/planetlila/moon/index.html
| access-date = June 14, 2007
| archive-url = https://web.archive.org/web/20120717010420/http://www.gps.caltech.edu/~mbrown/planetlila/moon/index.html
| archive-date = July 17, 2012
| url-status = live
}}</ref>

<ref name="gemini.edu.tenth">{{cite web
| title = Gemini Observatory Shows That "10th Planet" Has a Pluto-Like Surface
| url = http://www.gemini.edu/index.php?option=content&task=view&id=142
| work = Gemini Observatory
| date = 2005
| access-date = May 3, 2007
| archive-url = https://web.archive.org/web/20070311021046/http://www.gemini.edu/index.php?option=content&task=view&id=142
| archive-date = March 11, 2007
| url-status = live
}}</ref>

<ref name="Brown-AJ2005-635">
{{cite journal
| title = Discovery of a Planetary-sized Object in the Scattered Kuiper Belt
| s2cid= 1761936 | journal = The Astrophysical Journal
| date = 2005
| volume = 635
| issue = 1
| pages = L97–L100
| doi = 10.1086/499336
| arxiv = astro-ph/0508633
| bibcode = 2005ApJ...635L..97B
}}
</ref>

<ref name="Licandro-AA2006-458">{{cite journal
| title = Visible spectroscopy of {{mp|2003 UB|313}}: evidence for N<sub>2</sub> ice on the surface of the largest TNO
| author1 = J. Licandro
| author2 = W. M. Grundy
| author3 = N. Pinilla-Alonso
| author4 = P. Leisy
| s2cid = 31587702
| journal = Astronomy and Astrophysics
| date = 2006
| volume = 458
| issue = 1
| pages = L5–L8
| doi = 10.1051/0004-6361:20066028
| url = http://www.aanda.org/articles/aa/pdf/2006/40/aa6028-06.pdf
| bibcode = 2006A&A...458L...5L
| arxiv = astro-ph/0608044
| access-date = November 14, 2006
| archive-url = https://web.archive.org/web/20081121031341/http://www.aanda.org/articles/aa/pdf/2006/40/aa6028-06.pdf
| archive-date = November 21, 2008
| url-status = live
}}</ref>

<ref name="Brown Van Dam et al. 2006">{{cite journal| doi = 10.1086/501524| last1 = Brown| first1 = M. E.|  last2 = Van Dam| first2 = M. A.| last3 = Bouchez| first3 = A. H.| last4 = Le Mignant| first4 = D.| last5 = Campbell| first5 = R. D.| last6 = Chin| first6 = J. C. Y.| last7 = Conrad| first7 = A.| last8 = Hartman| first8 = S. K.| last9 = Johansson| first9 = E. M.| last10 = Lafon| first10 = R. E.| last11 = Rabinowitz| first11 = D. L. Rabinowitz| last12 = Stomski| first12 = P. J. Jr.| last13 = Summers| first13 = D. M.| last14 = Trujillo| first14 = C. A.| last15 = Wizinowich| first15 = P. L.| s2cid = 2578831| year = 2006| title = Satellites of the Largest Kuiper Belt Objects| journal = The Astrophysical Journal| volume = 639| issue = 1| pages = L43–L46| arxiv = astro-ph/0510029| bibcode = 2006ApJ...639L..43B| url = http://web.gps.caltech.edu/~mbrown/papers/ps/gab.pdf| access-date = October 19, 2011| ref = {{sfnRef|Brown Van Dam et al.|2006}}| archive-url = https://web.archive.org/web/20131103094637/http://web.gps.caltech.edu/~mbrown/papers/ps/gab.pdf| archive-date = November 3, 2013| url-status = live}} <!-- {{sfn|Brown Van Dam et al.|2006}} --></ref>

<ref name="Tytell-ST2006">{{cite news
| last = Tytell
| first = David
| date = 2006
| title = All Hail Eris and Dysnomia
| work = Sky and Telescope
| url = http://www.skyandtelescope.com/astronomy-news/all-hail-eris-and-dysnomia/
| access-date = January 5, 2010
| archive-url = https://web.archive.org/web/20141227115433/http://www.skyandtelescope.com/astronomy-news/all-hail-eris-and-dysnomia/
| archive-date = December 27, 2014
| url-status = live
}}</ref>

<!--  <ref name="dic.ref.com-eris">{{cite web
| title = Define Eris
| work = Dictionary.com
| publisher = Random House
| url = http://dictionary.reference.com/browse/eris
| access-date = October 4, 2012
| archive-url = https://web.archive.org/web/20121102063658/http://dictionary.reference.com/browse/eris
| archive-date = November 2, 2012
| url-status = live
}}</ref>-->

<ref name="pluggd.tv-2007">
{{cite web
| title = Julia Sweeney and Michael E. Brown
| work = Hammer Conversations: KCET podcast
| url = http://www.pluggd.tv/audio/channels/kcet_podcast__hammer_conversations/episodes/2h10l
| date = 2007
| access-date = October 1, 2008
| archive-url = https://web.archive.org/web/20081006182705/http://www.pluggd.tv/audio/channels/kcet_podcast__hammer_conversations/episodes/2h10l <!--Added by H3llBot-->
| archive-date = October 6, 2008
}}
</ref>

<ref name="NBC2015-Pluto-n391321">{{cite web
| url = http://www.nbcnews.com/science/space/new-horizons-probe-finds-out-plutos-bigger-icier-we-thought-n391321
| title = New Horizons Probe Finds Out Pluto's Bigger (and Icier) Than We Thought
| work = NBC News
| date = July 13, 2015
| access-date = July 13, 2015
| archive-url = https://web.archive.org/web/20150713221741/http://www.nbcnews.com/science/space/new-horizons-probe-finds-out-plutos-bigger-icier-we-thought-n391321
| archive-date = July 13, 2015
| url-status = live
}}</ref>

<ref name="Duffard2008">{{cite journal
 |first1       = R.
 |last1        = Duffard
 |first2       = J. L.
 |last2        = Ortiz
 |first3       = P.
 |last3        = Santos-Sanz
 |first4       = A.
 |last4        = Mora
 |first5       = P. J.
 |last5        = Gutiérrez
 |first6       = N.
 |last6        = Morales
 |first7       = D.
 |last7        = Guirado
 |title        = A study of photometric variations on the dwarf planet (136199) Eris
 |url          = https://www.aanda.org/articles/aa/pdf/2008/09/aa8619-07.pdf
 |journal      = Astronomy & Astrophysics
 |date         = March 2008
 |volume       = 479
 |issue        = 3
 |pages        = 877–881
 |doi-access   = free
 |doi          = 10.1051/0004-6361:20078619
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<ref name="Roe2008">{{cite journal
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<ref name="Brown2023">{{cite journal |last1=Brown |first1=Michael E. |last2=Butler |first2=Bryan J. |title=Masses and Densities of Dwarf Planet Satellites Measured with ALMA |journal=The Planetary Science Journal |date=1 October 2023 |volume=4 |issue=10 |pages=193 |doi=10.3847/PSJ/ace52a|doi-access=free |arxiv=2307.04848 |bibcode=2023PSJ.....4..193B }}</ref>
}}

== External links ==
{{Commons}}
* Michael Brown's webpages about [http://www.gps.caltech.edu/~mbrown/planetlila/ Eris] and [http://www.gps.caltech.edu/~mbrown/planetlila/moon/ Dysnomia]
* [https://www.minorplanetcenter.net/db_search/show_object?object_id=Eris&commit=Show MPC Database entry for (136199) Eris]
* [https://web.archive.org/web/20050731232015/http://neo.jpl.nasa.gov/orbits/2003ub313.html 3D orbit visualization from NASA JPL]
* [http://www.orbitsimulator.com/gravity/articles/newtno.html Simulation of {{mp|2003 UB|313}}'s orbit]
* [https://web.archive.org/web/20060114202745/http://www2.keck.hawaii.edu/optics/staff/mvandam/gabrielle Keck observatory page about the discovery of Dysnomia]
* {{AstDys|136199}}
* {{JPL small body}}

{{Eris|state=expanded}}
{{Dwarf planets}}
{{Solar System}}

[[Category:Eris (dwarf planet)| ]]
[[Category:Dwarf planets]]
[[Category:Named minor planets]]

{{Sourceattribution|Eris (dwarf planet)}}