Variance-gamma distribution: Difference between revisions

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Please check talk page before editing about the November 2010 occultation event, and related Eris/Pluto size issues
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{{Infobox planet
| name = Eris
| symbol =
| image = [[File:Eris and dysnomia2.jpg|240px|Eris (centre) and Dysnomia (left of centre), taken by the [[Hubble Space Telescope]]]]
| caption = Eris (centre) and [[Dysnomia (moon)|Dysnomia]] (left of centre). <br> [[Hubble Space Telescope]]
| discovery = yes
| discoverer =
  {{plainlist |
* [[Michael E. Brown|M. E. Brown]]
* [[Chad Trujillo|C. A. Trujillo]]
* [[David L. Rabinowitz|D. L. Rabinowitz]]<ref name="discovery" />
  }}
| discovered = January 5, 2005<ref name="New Planet" /><ref group=lower-alpha>Images were taken on October 21, 2003, however the object was not detected and identified until 2005.</ref>
| mp_name = '''{{val|136199|u=Eris}}'''
| note = yes
| alt_names = {{mp|2003 UB|313}}<ref name="jpldata" />
| named_after = [[Eris (mythology)|Eris]]
| mp_category =
  {{plainlist |
* [[dwarf planet]]
* [[Trans-Neptunian object|TNO]]
* [[plutoid]]
* [[scattered disc|SDO]]
* [[minor planet moon|binary]]<ref name="MPC" /><ref name="Buie2007" />
  }}
| orbit_ref = <ref name="jpldata" />
| epoch = 2013-Apr-18 <br> ([[Julian day|JD]] {{val|2456400.5}})
| aphelion =
  {{plainlist |
* {{val|97.661|ul=AU}}
* {{val|14.602|e=9|u=km}}
  }}
| perihelion =
  {{plainlist |
* {{val|38.255|u=AU}}
* {{val|5.723|e=9|u=km}}
  }}
| semimajor =
  {{plainlist |
* {{val|67.958|u=AU}}
* {{val|10.166|e=9|u=km}}
  }}
| eccentricity = {{val|0.437083}}
| period =
  {{plainlist |
* {{val|204624|u=days}}
* {{val|560.23|u=[[julian year (astronomy)|years]]}}
  }}
| avg_speed = {{val|3.4338|u=km/s}}
| mean_anomaly = {{val|203.216|s=°}}
| inclination = {{val|43.8853|s=°}}
| asc_node = {{val|36.031|s=°}}
| arg_peri = {{val|150.800|s=°}}
| satellites = [[Dysnomia (moon)|Dysnomia]]
| physical_characteristics = yes
| mean_radius = {{val|1163|6|u=km}}<ref name="sicardy" /><ref name="Beatty2010-NewScientist" />
| mass =
  {{plainlist |
* {{nowrap|{{val|1.67|0.02|e=22|u=kg}}<ref name="Brown Schaller 2007" />}}
* 0.0028 [[Earth mass|Earths]]
* 0.23 [[Moon mass|Moons]]
  }}
| surface_area = {{val|17000000|u=km2}}
| density = {{nowrap|{{val|2.52|0.05|u=g/cm3}}}}<ref name="sicardy" /><ref name="Beatty2010-SkyTelescope" />
| surface_grav = {{Gr|16.7|1163|3}} [[Acceleration|m/s<sup>2</sup>]]<br>0.084 [[g-force|''g'']]<ref name="fact2">Calculated based on the known parameters</ref>
| escape_velocity = {{V2|16.7|1163|3}} km/s
| sidereal_day = {{val|25.9|8|u=hr}}<ref name="jpldata" />
| albedo = {{val|0.96|+0.09|-0.04}}<ref name="sicardy" />
| temperatures = yes
| temp_name1 = (approx)
| min_temp_1 = 30&nbsp;[[Kelvin|K]]
| mean_temp_1 = 42.5&nbsp;K
| max_temp_1 = 55&nbsp;K
| spectral_type = [[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 = &minus;1.19&nbsp;±&nbsp;0.3<ref name="jpldata" />
| angular_size = 40 [[milliarcsecond|milli-arcsec]]<ref name="Bertoldi Altenhoff et al. 2006" />
| pronounced = {{IPAc-en|ˈ|ɪər|ɨ|s}} or {{IPAc-en|ˈ|ɛr|ɨ|s}}{{refn|{{respell|EER|is}} or {{respell|ERR|is}}.<ref name="dic.ref.com-eris" /> Both are common; the former is the literary pronunciation of the name, but Brown and his students use the latter.<ref name="pluggd.tv-2007" />|group=lower-alpha}}
| adjectives = Eridian
}}
 
'''Eris''' ([[minor-planet designation]] '''{{val|136199|u=Eris}}''') is the most-massive known [[dwarf planet]] in the [[Solar System]] and the ninth-most-massive body known to directly orbit the [[Sun]].<ref group=lower-alpha name=footnoteI>It is, however, only the 16th-most-massive known body in the Solar System, because [[List of Solar System objects by size|seven moons]] are more massive than any known dwarf planet.</ref>{{refn|According to most recent estimates, Eris is ~1% larger<ref name="sicardy" /> and 25% more massive than Pluto.<ref name="Brown Schaller 2007" /> Given the [[error bar]]s in the different diameter estimates, it is currently unknown whether Eris or Pluto has the larger diameter.<ref name="Brown2010-Plutosize" /> Both Pluto and Eris are estimated to have solid-body diameters of about 2330&nbsp;km.<ref name="Brown2010-Plutosize" />|group=lower-alpha}} It is estimated to be 2326 (±12)&nbsp;km in diameter,<ref name="Beatty2010-NewScientist" /> and 27% more [[mass]]ive than [[Pluto]], or about 0.27% of the [[Earth]]'s mass.<ref name="Brown Schaller 2007" /><ref name="070614_eris_mass" />
 
Eris was discovered in January 2005 by a [[Palomar Observatory]]-based team led by [[Michael E. Brown|Mike Brown]], and its identity was verified later that year. It is a [[trans-Neptunian object]] (TNO) and a member of a high-eccentricity population known as the [[scattered disc]]. It has one known [[natural satellite|moon]], [[Dysnomia (moon)|Dysnomia]]. {{As of|2014}}, its distance from the Sun is 96.4&nbsp;[[Astronomical unit|AU]],<ref name="AstDys" /> roughly three times that of Pluto. With the exception of some [[comet]]s, Eris and Dysnomia are currently the most distant known natural objects in the Solar System.<ref name="New Planet" />{{refn|{{As of|2013}}, [[90377 Sedna|Sedna]] is 86.4&nbsp;[[astronomical unit|AU]] from the Sun,<ref name="AstDys-Sedna" /> whereas Eris is 96.5&nbsp;AU from the Sun.<ref name="AstDys" /> Eris is still close to its 1977 aphelion (furthest distance from the Sun), whereas Sedna is nearing its 2076 perihelion (closest approach to the Sun).<ref name="Horizons2076" /> Sedna will overtake Eris as the farthest presently known spherical [[minor planet]] in 2114.<ref name="Horizons2076" />|group=lower-alpha}}
 
Because Eris appeared to be larger than Pluto, its discoverers<ref name="mbrown-planetlila" /> and [[NASA]] initially described it as the Solar System's [[Planets beyond Neptune|tenth planet]]. This, along with the prospect of other similarly sized objects being discovered in the future, motivated the [[International Astronomical Union]] (IAU) to [[definition of planet|define the term ''planet'']] for the first time. Under the [[IAU definition of planet|IAU definition]] approved on August&nbsp;24, 2006, Eris is a "dwarf planet", along with objects such as [[Pluto]], [[Ceres (dwarf planet)|Ceres]], [[Haumea (dwarf planet)|Haumea]] and [[Makemake (dwarf planet)|Makemake]].<ref name="IAUPressRelease2006" />
However, observations of a stellar [[occultation]] by Eris in 2010 showed that its diameter was only 2,326&nbsp;km, give or take 12&nbsp;km, not significantly different from the size of Pluto.<ref name="Brown2010-occult" /> Given the [[error bar|uncertainties]] in their size estimates, there is a reasonable chance that Eris is actually smaller than Pluto.<ref name="Brown2010-Plutosize" /><ref group=lower-alpha>For r(Eris) = 1163±6 and r(Pluto) = 1153±10, and assuming normal distributions, the chance that
Eris is smaller than Pluto is
 
<math>\Phi\left(\frac{r_P-r_E}{\sqrt{\sigma_P^2 + \sigma_E^2}}\right) = \frac12\left[1 + \operatorname{erf}\left(\frac{r_P-r_E}{\sqrt{\sigma_P^2 + \sigma_E^2}\sqrt{2}}\right)\right]</math>,
 
where {{angbr|Φ}} is the [[cumulative distribution function]] and {{angbr|erf}} is the [[error function]].  Erf(&minus;0.6064) = &minus;0.6088, and Φ = 0.1956, or an approximately 20% chance.</ref>
 
== Discovery ==
 
Eris was discovered by the team of [[Michael E. Brown|Mike Brown]], [[Chad Trujillo]], and [[David L. Rabinowitz|David Rabinowitz]]<ref name="New Planet" /> on January&nbsp;5, 2005, from images taken on October&nbsp;21, 2003. The discovery was announced on July&nbsp;29, 2005, the same day as {{dp|Makemake}} and two days after {{dp|Haumea}},<ref name="MaughJohnson" /> due in part to [[Controversy over the discovery of Haumea|events that would later lead to controversy about the latter]].  The search team had been systematically scanning for large outer [[Solar System]] bodies for several years, and had been involved in the discovery of several other large TNOs, including [[50000 Quaoar]], [[90482 Orcus]], and [[90377 Sedna]].
 
Routine observations were taken by the team on October&nbsp;21, 2003, using the 1.2&nbsp;m [[Samuel Oschin telescope|Samuel Oschin]] [[Schmidt telescope]] at [[Mount 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]]s per hour to reduce the number of [[false positive]]s returned. When [[90377 Sedna|Sedna]] was discovered, 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 motion against the background [[star]]s.
 
[[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.]]
[[File:TheTransneptunians 73AU.svg|left|thumb|Distribution of trans-Neptunian objects]]
 
Follow-up observations were then carried out to make a preliminary determination of Eris's [[orbit]], which allowed the object's distance to be estimated. 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 [[Controversy over the discovery of Haumea|controversially announced]] on July 27 by a different team in Spain.<ref name="New Planet" />
 
More observations released in October 2005 revealed that Eris had a moon, later named [[Dysnomia (moon)|Dysnomia]]. Observations of Dysnomia's orbit permitted scientists to determine the mass of Eris, which in June 2007 they calculated to be {{val|1.66|0.02|e=22|u=kg}}, 27% greater than Pluto's.
 
== Classification ==
 
Eris is a [[plutoid]], that is, a [[trans-Neptunian object|trans-Neptunian]] [[dwarf planet]].<ref name="plutoid" /> Its orbital characteristics more specifically categorize it a [[scattered disc|scattered-disk object]] (SDO), or a TNO that is believed to have been "scattered" from the [[Kuiper belt]] into more distant and unusual [[orbit]]s following gravitational interactions with [[Neptune]] as the [[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" /> Inner-belt objects are expected to be generally more massive than outer-belt objects, and so astronomers expect to discover more large objects like Eris in high-inclination orbits, which have traditionally been neglected.
 
Because Eris may be larger than [[Pluto]], it was initially described as the "[[tenth planet]]" by [[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 [[planet]], the [[International Astronomical Union|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 ''[[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 ''[[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 [[List of minor planets|Minor Planet Catalogue]], designating it ''(136199) Eris.''<ref name="IAUC 8747" />
 
== Name ==
 
[[File:Eris (Discordia).jpg|thumb|150px|[[Athens|Athenian]] painting of [[Eris (mythology)|Eris]], circa 550&nbsp;BC]]
 
Eris is named after the goddess [[Eris (mythology)|Eris]] (Greek ''{{lang|grc|Ἔρις}}),'' a personification of strife and discord.<ref name="USGS-UB-313" /> The name was assigned on September&nbsp;13, 2006, following an unusually long period in which the object was known by the [[Provisional designation in astronomy|provisional designation]] '''{{mp|2003 UB|313}}''', which was granted automatically by the [[International Astronomical Union|IAU]] under their naming protocols for [[minor planet]]s. The regular adjectival form of ''Eris'' is ''Eridian.''
 
=== Xena ===
 
Due to uncertainty over whether the object would be classified as a [[planet]] or a [[minor planet]], because different nomenclature procedures apply to these different classes of objects,<ref name="IAU-2003-UB313" /> the decision on what to name the object had to wait until after the August&nbsp;24, 2006, IAU ruling.<ref name="IAUC 8747" /> As a result, for a time the object became known to the wider public as ''Xena''.
 
"Xena" was an informal name used internally by the discovery team. It was inspired by the eponymous heroine 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,
 
{{quote
| We chose it since it started with an X ([[planet X|planet "X"]]), it sounds mythological (OK, so it's TV&nbsp;mythology, but Pluto [[Pluto (Disney)|is named after a cartoon]], right?),{{refn|Brown is joking on this point. It was in fact [[Pluto (Disney)|the Disney character Pluto]] that was named after the newly discovered "planet", though [[Venetia Phair]], Pluto's christener, had to counter accusations her whole life that she named the planet after a cartoon dog.<ref name="BBC2007-dog-girl" />|group=lower-alpha}} and (this part is actually true) we've been working to get more female deities out there (''i.e.'' [[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" />
}}
 
"We assumed [that] a real name would come out fairly quickly, [but] the process got stalled," Mike Brown said in interview,
 
{{quote
| One reporter called me up from the ''[[New York Times]]'' who happened to have been a friend of mine from college, [and] I was a little less guarded with him than I am with the normal press. He 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?"... 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:Artist's impression dwarf planet Eris.jpg|thumb|Artist's impression of the dwarf planet Eris. This artistic representation is based on observations made at [[ESO]]'s [[La Silla]] Observatory.<ref name="Pluto's Twin" />]]
 
According to science writer [[Govert Schilling]], Brown initially wanted to call the object "[[Lila (Hinduism)|Lila]]", after a concept in [[Hindu mythology]] that described the cosmos as the outcome of a game played by [[Brahma]]. The name was very similar to "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 [[90377 Sedna|Sedna]] a year previously, and had been heavily criticised. However, he listed the address of his personal web page announcing the discovery as ''/~mbrown/planetlila'' and in the chaos following the [[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 ''[[Persephone]]'', the wife of the god [[Pluto (mythology)|Pluto]], would be a good name for the object.<ref name="New Planet" /> The name had been used several times in [[science fiction]],<ref name="TechRepublic2006" /> and was popular with the public, having handily won a poll conducted by ''[[New Scientist]]'' magazine ("Xena", despite only being a nickname, came fourth).<ref name="O'Neill2005-NewScientist" /> However, this was not possible once the object was classified as a dwarf planet, because there is already an [[asteroid]] with that name, [[399 Persephone]].<ref name="New Planet" /> Because [[Astronomical naming conventions|IAU regulations]] require a name from [[creation myth]]ology for objects with orbital stability beyond [[Neptune]]'s orbit, the team had also been considering such possibilities.<ref name="caltech" />
 
With the dispute resolved, the discovery team proposed ''[[Eris (mythology)|Eris]]'' on September&nbsp;6, 2006. On September&nbsp;13, 2006 this name 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 [[planet]] for so long, it deserved a name from [[Greek mythology|Greek]] or [[Roman mythology]], like the other planets. However, the asteroids had taken the vast majority of Graeco-Roman names. ''Eris'', whom Brown described as his favourite goddess, had fortunately escaped inclusion.<ref name="WGBH" /> The name in part reflects the discord in the astronomical community caused by the debate over the object's (and Pluto's) nature.
 
== Orbit ==
 
[[File:Eris Orbit.svg|left|thumb|The orbit of Eris (blue) compared to those of [[Saturn]], [[Uranus]], Neptune, and Pluto (white/grey). The arcs below the ecliptic are plotted in darker colours, 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.]]
[[File:Eris800yearsb.gif|thumb|The distances of Eris and Pluto from the Sun in the next 1,000 years]]
 
Eris has an [[orbital period]] of 557 [[Julian year (astronomy)|year]]s, and as of 2011 lies at 96.6&nbsp;[[astronomical unit|AU]]s from the [[Sun]],<ref name="AstDys" /> almost its maximum possible distance (its [[Apsis|aphelion]] is 97.5&nbsp;AU). It came to [[perihelion]] between 1698<ref name="Buie2007" /> and 1699,<ref name="horizons" /> to aphelion around 1977,<ref name="horizons" /> and will return to perihelion around 2256<ref name="horizons" /> to 2258.<ref name="Johnston2007" /> Eris and its moon are currently the most distant known objects in the Solar System apart from [[long-period comet]]s and [[space probe]]s.<ref name="Peat-Heavens-Above-dubious-source" /> However, approximately forty known [[trans-Neptunian object|TNO]]s, most notably {{mpl|2006 SQ|372}}, {{mpl-|87269|2000 OO|67}} and {{dp|Sedna}}, though currently closer to the Sun than Eris, have greater average orbital distances than Eris's [[semimajor axis]] of 67.7&nbsp;AU.<ref name="MPC" />
 
The Eridian orbit is highly [[orbital eccentricity|eccentric]], and brings Eris to within 37.9&nbsp;AU of the Sun, a typical perihelion for [[scattered disk|scattered objects]]. This is within the orbit of Pluto, but still safe from direct interaction with Neptune (29.8–30.4&nbsp;AU). Pluto, on the other hand, like other [[plutino]]s, follows a less inclined and less eccentric orbit and, protected by [[orbital resonance]], can cross Neptune's orbit. It is possible that Eris is in a 17:5&nbsp;resonance with Neptune, though further observations will be required to check that hypothesis.<ref name="orbitsimulator" /> Unlike the eight planets, whose orbits all lie roughly in the same plane as the Earth's, Eris's orbit is highly [[inclination|inclined]]: It is tilted at an angle of about 44&nbsp;[[degree (angle)|degrees]] to the [[ecliptic]]. In about 800&nbsp;years, Eris will be closer to the Sun than Pluto for some time (see the graph at the right).
 
Eris currently has an [[apparent magnitude]] of 18.7, making it bright enough to be detectable to some amateur [[telescope]]s. A 200&nbsp;mm telescope with a [[Charge-Coupled Device|CCD]] can detect Eris under favourable 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]</ref> The reason it had not been noticed until now is its steep orbital inclination; most searches for large outer Solar System objects concentrate on the ecliptic plane, where most bodies are found.
 
Eris is now in the constellation [[Cetus (constellation)|Cetus]]. It was in [[Sculptor (constellation)|Sculptor]] from 1876 until 1929 and [[Phoenix (constellation)|Phoenix]] from roughly 1840 until 1875. In 2036 it will enter [[Pisces (constellation)|Pisces]] and stay there until 2065, when it will enter [[Aries (constellation)|Aries]].<ref name="horizons" /> It will then move into the [[celestial sphere|northern sky]], entering [[Perseus (constellation)|Perseus]] in 2128 and [[Camelopardalis]] (where it will reach its northernmost [[declination]]) in 2173.  Also, because of the high inclination of its orbit, Eris only passes through a few constellations of the traditional [[Zodiac]].
 
== Size, mass and density ==
 
{{TNO imagemap}}
 
{| class="wikitable plainrowheaders" style="float: right; margin-left: 1em;"
|+ '''Size estimates'''
|-
! scope="col" | Year !! Radius (Diameter) !! Source
|-
! scope="row" | 2005
| 1,199 (2,397) km<!--1198.5--><ref name="hst1" />
| [[Hubble Space Telescope|Hubble]]
|-
! scope="row" | 2007
| 1,300 (2,600) km<ref name="spitzer" />
| [[Spitzer Space Telescope|Spitzer]]
|-
! scope="row" | 2011
| 1,163 (2,326) km<ref name="sicardy" />
| [[Occultation#Occultations by asteroids|Occultation]]
|}
 
In 2005, the [[diameter]] of Eris was measured to be 2,397&nbsp;km, give or take 100&nbsp;km, using images from the [[Hubble Space Telescope]] (HST).<ref name="hst1" /><ref name="Bertoldi2006" /> The size of an object is determined from its [[Absolute magnitude#Solar System bodies (H)|absolute magnitude]] (H) and the [[albedo]] (the amount of light it reflects). At a distance of 97&nbsp;AU, an object with a diameter of 3,000&nbsp;km would have an [[angular size]] of 40&nbsp;[[Minute of arc|milliarcsecond]]s,<ref name="Bertoldi Altenhoff et al. 2006" /> which is directly measurable with the Hubble Space Telescope. Although resolving such small objects is at the very limit of the telescope's capabilities,<ref group=lower-alpha>The Resolution of the High Resolution Channel of the [[Advanced Camera for Surveys|ACS]] is 40&nbsp;marcsec (milliarcseconds) and the size of 1 pixel is ~25&nbsp;marcsec i.e. ~1875&nbsp;km at the distance of Eris.</ref> sophisticated image processing techniques such as [[deconvolution]] can be used to measure such angular sizes fairly accurately.{{refn|The reference to 'direct' measure by HST should not mislead into thinking that this method is as 'direct' and model-independent as measuring say [[Neptune|Neptune's]] size. Basically, the method consists in finding the statistically best fit to a ''smeared'' image of the size of less than 2 pixels by comparing it with smeared images of the background [[star]]s, using a given computer model of the optics ([[point spread function|PSF]]). A non-technical description of the method is given on [http://www.gps.caltech.edu/~mbrown/planetlila/index.html#size Brown's page], a detailed description of this approach and its limitations are discussed in a paper on {{dp|Quaoar}}<ref name="Brown-AJ2004-127" />|group=lower-alpha}}
 
This makes Eris around the same size as Pluto, which is about 2,330&nbsp;km across. It also indicates an [[Bond albedo|albedo]] of 0.96, higher than that of any other large body in the Solar System except [[Enceladus (moon)|Enceladus]].<ref name="sicardy" /> It is speculated that the high albedo is due to the surface ices being replenished because of temperature fluctuations because Eris's eccentric orbit takes it closer and farther from the Sun.<ref name="Brown-2003-UB313" />
 
In 2007, a series of observations of the largest trans-Neptunian objects with the [[Spitzer Space Telescope]] gave an estimate of Eris's diameter of {{val|2600|+400|-200|u=km}}.<ref name="spitzer" /> The Spitzer and Hubble estimates overlap in the range of 2,400–2,500&nbsp;km, 4–8% larger than Pluto. However, astronomers now suspect that Eris's spin axis is pointing toward the sun, at the moment—a possibility that would keep the sunlit hemisphere warmer than average and skew any [[infrared]] measurements toward higher values.<ref name="Beatty2010-NewScientist" /> So the outcome from the 2010 Chile [[Occultation#Occultations by asteroids|occultation]] is actually more in line with the Hubble result from 2005.<ref name="Beatty2010-NewScientist" />
 
In November 2010, Eris was the subject of one of the most distant stellar occultations yet achieved 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|-12|u=km}}.<ref name="sicardy" /> However, when using data from this event for comparison to Pluto, there is a range of figures available for Pluto's radius/diameter that can be selected.<ref name="Young07" /> This is due in part to Pluto's atmosphere that interferes with making measurements of its solid surface (as opposed to gaseous haze).<ref name="Young07" />
<!--
NASA's New Horizon's spacecraft will attempt a new measurement of Pluto's diameter in 2015 as it approaches the icy orb, according to Alan Stern, New Horizon's Principal Investigator.
-->
The mass of Eris can be calculated with much greater precision. Based on the currently accepted value for Dysnomia's period—15.774 days—<ref name="Brown Schaller 2007" /><ref name="Brown-planetlila-moon" /> Eris is 27&nbsp;percent more massive than Pluto. If the 2011 occultation results are used, then Eris has a density of 2.52±0.05 g/cm<sup>3</sup>; substantially denser than Pluto, and thus must be composed largely of rocky materials.<ref name="sicardy" />
 
== Surface and atmosphere ==
 
[[File:2003 UB313 near-infrared spectrum.gif|thumb|The infrared spectrum of Eris, compared to that of Pluto, shows the marked similarities between the two bodies. Arrows denote methane absorption lines.]]
[[File:2006-16-a-full-1-.jpg|thumb|left|Artist's impression of Eris and Dysnomia. Eris is the main object, Dysnomia the small grey disk just above it. The flaring object top-left is the Sun.]]
 
The discovery team followed up their initial identification of Eris with [[astronomical spectroscopy|spectroscopic]] observations made at the 8&nbsp;m [[Gemini North Telescope]] in Hawaii on January&nbsp;25, 2005. Infrared light from the object revealed the presence of [[methane]] ice, indicating that the surface may be similar to that of Pluto, which at the time was the only [[trans-Neptunian object|TNO]] known to have surface methane, and of Neptune's moon [[Triton (moon)|Triton]], which also has methane on its surface.<ref name="gemini.edu.tenth" /> Note that no surface details can be resolved from Earth or its orbit with any instrument currently available.
 
Due to Eris's distant eccentric orbit, Eridian surface temperature is estimated to vary between about 30 and 56 kelvin (−243 and −217&nbsp;degrees Celsius).<ref name="New Planet" />
 
Unlike the somewhat reddish Pluto and Triton, however, Eris appears almost grey.<ref name="New Planet" /> Pluto's reddish colour is believed to be due to deposits of [[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 away from the Sun that methane can [[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" />
 
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 [[sublimation (physics)|sublime]]. Because methane is highly [[Volatility (chemistry)|volatile]], its presence shows either that Eris has always resided in the distant reaches of the Solar System where it is cold enough for methane ice to persist, or that the celestial body has an internal source of methane to replenish gas that escapes from its [[atmosphere]]. This contrasts with observations of another discovered TNO, {{dp|Haumea}}, which reveal the presence of [[water]] ice but not methane.<ref name="Licandro-AA2006-458" />
 
== Moon ==
 
{{main | Dysnomia (moon) }}
 
In 2005, the [[adaptive optics]] team at the [[Keck telescopes]] in Hawaii carried out observations of the four brightest [[trans-Neptunian object|TNOs]] ([[Pluto]], {{dp|Makemake}}, {{dp|Haumea}}, and Eris), using the newly commissioned [[laser guide star]] adaptive optics system.<ref name="Brown Van Dam et al. 2006" /> Images taken on September&nbsp;10 revealed a [[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 (Xena)|Gabrielle]]", after the television warrior princess's sidekick. When Eris received its official name from the IAU, the moon received the name ''[[Dysnomia (moon)|Dysnomia]],'' after the [[Dysnomia (mythology)|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 TV by [[Lucy Lawless]].<ref name="Tytell-ST2006" />
 
== See also ==
 
{{Portal|Solar System}}
{{Wikipedia books
| 1 = Dwarf Planets Of The Solar System & Their Satellites
| 3 = Solar System
}}
 
* [[Astronomical naming conventions]]
* [[Clearing the neighbourhood]]
* [[International Astronomical Union]]
* [[Planets beyond Neptune]]
 
== 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
| colwidth = 30em
| refs =
 
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{{cite web
| author = Staff
| date = 2007-05-01
| url = http://www.minorplanetcenter.org/iau/lists/NumberedMPs.html
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}}
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<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
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<ref name="jpldata">
{{cite web
| date = 2009-11-20 last obs
| title = JPL Small-Body Database Browser: 136199 Eris (2003 UB313)
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<ref name="MPC">
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}}
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<ref name="Buie2007">
{{cite web
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| date = 2007-11-06
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}}
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<ref name="sicardy">
{{cite journal
| title = Size, density, albedo and atmosphere limit of dwarf planet Eris from a stellar occultation
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<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 = http://www.newscientist.com/article/dn19697-former-tenth-planet-may-be-smaller-than-pluto.html
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}}
</ref>
 
<ref name="Brown Schaller 2007">
{{cite doi | 10.1126/science.1139415 }} <!-- {{sfn|Brown Schaller|2007}} -->
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<ref name="Beatty2010-SkyTelescope">
{{cite web
| last = Beatty
| first = Kelly
| date = 2010-11-07
| title = Eris Gets Dwarfed (Is Pluto Bigger?)
| publisher = Sky & Telescope (News Blog)
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<ref name="Snodgrass et al. 2010">
{{cite doi | 10.1051/0004-6361/200913031 }} <!-- {{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 = http://hamilton.dm.unipi.it/astdys/index.php?pc=1.1.3.0&n=Eris
| accessdate = 2009-03-16
}}
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<ref name="Bertoldi Altenhoff et al. 2006">
{{cite doi | 10.1038/nature04494 }} <!-- {{sfn|Bertoldi Altenhoff et al.|2006}} -->
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<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
| year = 2007
| accessdate = 2007-06-14
}}
</ref>
 
<ref name="mbrown-planetlila">
{{cite web
| last = Brown
| first = Mike
| year = 2006
| title = The discovery of 2003 UB313 Eris, the <s>10th planet</s> largest known dwarf planet
| url = http://web.gps.caltech.edu/~mbrown/planetlila/
| publisher = Caltech
| accessdate = 2010-01-05
}}
</ref>
 
<ref name="IAUPressRelease2006">
{{cite press release
| publisher = [[IAU]]
| date = 2006-08-16
| title = The IAU draft definition of "planet" and "plutons"
| url = http://www.iau2006.org/mirror/www.iau.org/iau0601/iau0601_release.html
| accessdate = 2006-08-16
}}
</ref>
 
<ref name="Brown2010-occult">
{{cite web
| last = Brown
| first = Mike
| year = 2010
| title = The shadowy hand of Eris
| publisher = Mike Brown's Planets
| url = http://www.mikebrownsplanets.com/2010/11/shadowy-hand-of-eris.html
| accessdate = 2010-11-07
}}
</ref>
 
<ref name="Brown2010-Plutosize">
{{cite web
| last = Brown
| first = Mike
| date = 2010-11-22
| title = How big is Pluto, anyway?
| publisher = Mike Brown's Planets
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</ref>
 
<ref name="MaughJohnson">
{{cite news
| title = His Stellar Discovery Is Eclipsed
| author = Thomas H. Maugh II and John Johnson Jr.
| work = Los Angeles Times
| url = http://articles.latimes.com/2005/oct/16/local/me-planet16
| accessdate = 2008-07-14
| date = 2005-10-16
}}
</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 = 2008-06-11
| accessdate = 2008-06-11
}}
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<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
| author = Gomes R. S., Gallardo T., Fernández J. A., Brunini A.
| journal = Celestial Mechanics and Dynamical Astronomy
| year = 2005
| volume = 91
| issue = 1–2
| pages = 109–129
| doi = 10.1007/s10569-004-4623-y
| bibcode = 2005CeMDA..91..109G
}}
</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
| year = 2005
| accessdate = 2007-05-03
}}
</ref>
 
<ref name="IAU 2006 5&6">
{{cite news
| url = http://www.iau.org/Resolutions_5-6.398.0.html
| title = IAU 2006 General Assembly: Resolutions 5 and 6
| date = 2006-08-24
| 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
| year = 2006
| accessdate = 2007-05-03
}}
</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
| url = http://www.cbat.eps.harvard.edu/iauc/08700/08747.html
| accessdate = 2012-01-12
| ref = {{sfnRef|IAUC 8747}}
}}
</ref>
 
<ref name="USGS-UB-313">
{{cite web
| last = Blue
| first = Jennifer
| title = 2003 UB 313 named Eris
| date = 2006-09-14
| work = USGS Astrogeology Research Program
| url = http://astrogeology.usgs.gov/HotTopics/index.php?/archives/211-2003-UB313-named-Eris.html
| accessdate = 2007-01-03
}}
</ref>
 
<ref name="IAU-2003-UB313">
{{cite web
| title = International Astronomical Association homepage
| url = http://www.iau.org/IAU/FAQ/2003_UB313.html/
| accessdate = 2007-01-05
| archiveurl = https://web.archive.org/web/20070930155414/http://www.iau.org/IAU/FAQ/2003_UB313.html/
| archivedate = 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
| format = PDF
| accessdate = 2007-05-03
}}
 
</ref>
 
<ref name="WGBH">
{{cite web
| last = Brown
| first = Mike
| year = 2007
| title = Lowell Lectures in Astronomy
| work = WGBH
| url = http://forum.wgbh.org/content/forum/3710-2007_04_11.mp3
| accessdate = 2008-07-13
}}
</ref>
 
<ref name="Pluto's Twin">
{{cite news
| title = Faraway Eris is Pluto's Twin
| newspaper = ESO Science Release
| date = 26 October 2011
| url = http://www.eso.org/public/news/eso1142/
| accessdate = 28 October 2011
}}
</ref>
 
<ref name="Schilling2008">
{{cite book
| last = Schilling
| first = Govert
| year = 2008
| title = The Hunt For Planet X
| publisher = Springer
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}}
</ref>
 
<ref name="TechRepublic2006">
{{cite web
| title = Planet X Marks the Spot
| work = TechRepublic
| year = 2006
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}}
</ref>
 
<ref name="O'Neill2005-NewScientist">
{{cite web
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| first = Sean
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| work = NewScientist
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</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/
| accessdate = 2007-01-05
}}
</ref>
 
<ref name="IAU0605">
{{cite web
| title = IAU0605: IAU Names Dwarf Planet Eris
| publisher =
| date = 2006-09-14
| work = International Astronomical Union News
| url = http://www.iau.org/iau0605_Eris.409.0.html
| accessdate = 2007-01-05
}}
</ref>
 
<ref name="horizons">
{{cite web
| last = Yeomans
| first = Donald K.
| title = Horizons Online Ephemeris System
| publisher = California Institute of Technology, Jet Propulsion Laboratory
| url = http://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=sb&sstr=Eris
| accessdate = 2007-01-05
}}
</ref>
 
<ref name="Johnston2007">
{{cite web
| last = Johnston
| first = Wm. Robert
| date = 2007-08-21
| title = (136199) Eris and Dysnomia
| publisher = Johnston's Archive
| url = http://www.johnstonsarchive.net/astro/astmoons/am-136199.html
| accessdate = 2007-07-27
}}
</ref>
 
<ref name="Peat-Heavens-Above-dubious-source">
{{cite web
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| publisher = Heavens-Above
| url = http://www.heavens-above.com/solar-escape.asp
| accessdate = 2008-01-25
}} {{Dead link|date=March 2012|bot=H3llBot}}
</ref>
 
<ref name="orbitsimulator">
[http://www.orbitsimulator.com/gravity/articles/newtno.html Simulation of Eris ({{mp|2003 UB|313}})'s orbit predicting a 17:5&nbsp;resonance]
</ref>
 
<ref name="hst1">
{{cite web
| title = Hubble Finds 'Tenth Planet' Slightly Larger Than Pluto
| date = 2006-04-11
| publisher = NASA
| url = http://www.nasa.gov/mission_pages/hubble/hst_xena_20060410.html
| accessdate = 2008-08-29
}}
</ref>
 
<ref name="spitzer">
{{cite arXiv
| author = John Stansberry, Will Grundy, Mike Brown, John Spencer, David Trilling, Dale Cruikshank, Jean-Luc Margot
| year = 2007
| title = Physical Properties of Kuiper Belt and Centaur Objects: Constraints from Spitzer Space Telescope
| class = astro-ph
| eprint = astro-ph/0702538
}}
</ref>
 
<ref name="Bertoldi2006">
{{cite web
| title = Comment on the recent Hubble Space Telescope size measurement of 2003 UB313 by Brown et al.
| url = http://www.astro.uni-bonn.de/~bertoldi/ub313/
| work = Max Planck Institute
| year = 2006
| accessdate = 2007-05-03
}}
</ref>
 
<ref name="Brown-2003-UB313">
{{cite journal
| title = Direct measurement of the size of 2003 UB313 from the Hubble Space Telescope
| author = [[Michael E. Brown|M. E. Brown]], E.L. Schaller, H.G. Roe, [[David L. Rabinowitz|D. L. Rabinowitz]], [[Chadwick A. Trujillo|C. A. Trujillo]]
| journal = The Astronomical Journal
| year = 2006
| volume =643
| issue = 2
| pages = L61–L63
| doi = 10.1086/504843
| url = http://www.gps.caltech.edu/~mbrown/papers/ps/xsize.pdf
| format = PDF
| bibcode = 2006ApJ...643L..61B
| arxiv = astro-ph/0604245
}}
</ref>
 
<ref name="Young07">
{{cite journal
| last1 = Young
| first1 = Eliot F.
| last2 = Young
| first2 = L. A.
| last3 = Buie
| first3 = M.
| year = 2007
| title = Pluto's Radius
| journal = Bulletin of the American Astronomical Society
| volume = 39
| pages = 541
| bibcode = 2007DPS....39.6205Y
| last4 = Buie
}}
</ref>
 
<ref name="Brown-planetlila-moon">
{{cite web
| last = Brown
| first = Mike
| year = 2007
| title = Dysnomia, the moon of Eris
| work = CalTech
| url = http://www.gps.caltech.edu/~mbrown/planetlila/moon/index.html
| accessdate = 2007-06-14
}}
</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
| year = 2005
| accessdate = 2007-05-03
}}
</ref>
 
<ref name="Brown-AJ2005-635">
{{cite journal
| title = Discovery of a Planetary-sized Object in the Scattered Kuiper Belt
| author = [[Michael E. Brown|M. E. Brown]], [[Chadwick A. Trujillo|C. A. Trujillo]], [[David L. Rabinowitz|D. L. Rabinowitz]]
| journal = The Astrophysical Journal
| year = 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
| author = J. Licandro, W. M. Grundy, N. Pinilla-Alonso, P. Leisy
| journal = Astronomy and Astrophysics
| year = 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
}}
</ref>
 
<ref name="Brown Van Dam et al. 2006">
{{cite doi | 10.1086/501524 }} <!-- {{sfn|Brown Van Dam et al.|2006}} -->
</ref>
 
<ref name="Tytell-ST2006">
{{cite web
| last = Tytell
| first = David
| year = 2006
| title = All Hail Eris and Dysnomia
| work = Sky and Telescope
| url = http://www.skyandtelescope.com/news/home/3916126.html
| accessdate = 2010-01-05
}}
</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
| accessdate = 2012-10-04
}}
</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
| year = 2007
| accessdate = 2008-10-01
| archiveurl = https://web.archive.org/web/20081006182705/http://www.pluggd.tv/audio/channels/kcet_podcast__hammer_conversations/episodes/2h10l <!--Added by H3llBot-->
| archivedate = 2008-10-06
}}
</ref>
 
<ref name="BBC2007-dog-girl">
{{cite news
| title = The girl who named a planet
| work = BBC News
| date = 2006-01-13
| url = http://news.bbc.co.uk/1/hi/sci/tech/4596246.stm
| accessdate = 2007-06-21
}}
</ref>
 
<ref name="Brown-AJ2004-127">
{{cite journal
| title = Direct Measurement of the Size of the Large Kuiper Belt Object (50000) Quaoar
| author = [[Michael E. Brown|M. E. Brown]] and [[Chadwick A. Trujillo|C. A. Trujillo]]
| journal = The Astronomical Journal
| year = 2004
| volume = 127
| issue = 7076
| pages = 2413–2417
| doi = 10.1086/382513
| url = http://www.gps.caltech.edu/~mbrown/papers/ps/qu.pdf
| format = PDF
| bibcode = 2004AJ....127.2413B
}} Describing in detail the method applied to the recent measure of {{mp|2003 UB|313}}.
</ref>
 
<ref name="AstDys-Sedna">
{{cite web
| title = AstDys (90377) Sedna Ephemerides
| publisher = Department of Mathematics, University of Pisa, Italy
| url = http://hamilton.dm.unipi.it/astdys/index.php?pc=1.1.3.0&n=Sedna
| accessdate = 2009-03-16
}}
</ref>
 
<ref name="Horizons2076">
{{cite web
| url = http://home.surewest.net/kheider/astro/Sedna2076.txt
| title = Horizons Output for Sedna 2076/2114
| author = [[JPL Horizons On-Line Ephemeris System]]
| date = 2010-07-18
| accessdate = 2010-07-18
}} [http://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=sb&sstr=Sedna Horizons]
</ref>
}}
 
== External links ==
 
{{Commons category|Eris}}
* [http://www.minorplanetcenter.net/db_search/show_object?object_id=Eris&commit=Show MPC Database entry for (136199) Eris]
* [http://www.gps.caltech.edu/~mbrown/planetlila/ Michael Brown's webpage about Eris]
* [http://www.gps.caltech.edu/~mbrown/planetlila/moon/ Brown's webpage about Dysnomia]
* [http://www.pluggd.tv/audio/channels/kcet_podcast__hammer_conversations/episodes/2h10l 2007 KCET interview of Mike Brown about Eris and Haumea with Julia Sweeney]
* [http://www.johnstonsarchive.net/astro/astmoons/am2003ub313.html compiled list of data]
* [http://www.minorplanetcenter.net/mpec/K05/K05O41.html MPEC listing for {{mp|2003 UB|313}}]
* [http://neo.jpl.nasa.gov/orbits/2003ub313.html Java 3D orbit visualization]
* [http://www.spaceflightnow.com/news/n0509/09solarssytem/ Spaceflight Now article about {{mp|2003 UB|313}} (Eris), {{mp|2003 EL|61}}, and {{mp|2005 FY|9}} (Makemake)]
* [http://www.slackerastronomy.org/wordpress/index.php/archive/10th-planet/#comments Slacker Astronomy Interview With Co-Discoverer Trujillo]
* [http://www.iau.org/TRANS-NEPTUNIAN_OBJECT_2003_UB.324.0.html Trans-Neptunian Object {{mp|2003 UB|313}}]—IAU statement regarding the planetary status of Eris
* [http://www.orbitsimulator.com/gravity/articles/newtno.html Simulation of {{mp|2003 UB|313}}'s orbit]
* [http://www2.keck.hawaii.edu/optics/staff/mvandam/gabrielle Keck observatory page about the discovery of Dysnomia]
* [http://pr.caltech.edu/media/Press_Releases/PR12724.html Caltech Press Release, 7/29/2005] "Planetary Scientists Discover Tenth Planet".
* [http://www.spitzer.caltech.edu/Media/happenings/20050807/ Press release on the Spitzer Space Telescope trying to image {{mp|2003 UB|313}} again]
 
{{Eris}}
{{MinorPlanets Navigator|(136198) 2003 UJ296|PageName=(136199) Eris|(136200) 2003 VS5|state=autocollapse}}
{{Trans-Neptunian dwarf planets}}
{{Solar System}}
{{Featured article}}
 
{{DEFAULTSORT:Eris (Dwarf Planet)}}
[[Category:Eris (dwarf planet)| ]]
[[Category:Astronomical objects discovered in 2005]]
[[Category:Pluto's planethood]]
[[Category:Scattered disc and detached objects]]
 
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Revision as of 16:38, 19 February 2014

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