Eris

== Eris== Eris,   minor-planet designation  136199 Eris, is the most massive known   dwarf planet[c]   in the   Solar System  and the ninth most massive body known to orbit the Sun  directly. [c] [d]   <span style="color:rgb(0,0,0);font-family:sans-serif;line-height:19.1875px;">It is estimated to be 2326 (±12) km in diameter, <sup class="reference" id="cite_ref-Beatty2010-NewScientist_11-1" style="color:rgb(0,0,0);font-family:sans-serif;line-height:1em;">[9] <span style="color:rgb(0,0,0);font-family:sans-serif;line-height:19.1875px;">  <span style="color:rgb(0,0,0);font-family:sans-serif;line-height:19.1875px;">and 27% more <span style="color:rgb(0,0,0);font-family:sans-serif;line-height:19.1875px;">  massive<span style="color:rgb(0,0,0);font-family:sans-serif;line-height:19.1875px;">  <span style="color:rgb(0,0,0);font-family:sans-serif;line-height:19.1875px;">than <span style="color:rgb(0,0,0);font-family:sans-serif;line-height:19.1875px;">  Pluto<span style="color:rgb(0,0,0);font-family:sans-serif;line-height:19.1875px;">, or about 0.27% of the <span style="color:rgb(0,0,0);font-family:sans-serif;line-height:19.1875px;">  Earth<span style="color:rgb(0,0,0);font-family:sans-serif;line-height:19.1875px;">'s mass. <sup class="reference" id="cite_ref-Brown_Schaller_2007_12-2" style="color:rgb(0,0,0);font-family:sans-serif;line-height:1em;">[10] <sup class="reference" id="cite_ref-070614_eris_mass_20-0" style="color:rgb(0,0,0);font-family:sans-serif;line-height:1em;">[16]

<p style="margin-top:0.4em;margin-bottom:0.5em;line-height:19.1875px;color:rgb(0,0,0);font-family:sans-serif;">Eris was discovered in January 2005 by a Palomar Observatory-based team led by 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 moon, Dysnomia. As of 2011, its distance from the Sun is 96.6 AU,<sup class="reference" id="cite_ref-AstDys_15-1" style="line-height:1em;">[13]  roughly three times that of Pluto. With the exception of some comets, Eris and Dysnomia are currently the most distant known natural objects in the Solar System.<sup class="reference" id="cite_ref-New_Planet_2-1" style="line-height:1em;">[2] <sup class="reference" id="cite_ref-23" style="line-height:1em;">[e]

<p style="margin-top:0.4em;margin-bottom:0.5em;line-height:19.1875px;color:rgb(0,0,0);font-family:sans-serif;">Because Eris appeared to be larger than Pluto, its discoverers<sup class="reference" id="cite_ref-mbrown-planetlila_24-0" style="line-height:1em;">[19]  and NASA initially described it as the Solar System's tenth planet. This, along with the prospect of other similarly sized objects being discovered in the future, motivated the International Astronomical Union (IAU) to define the term planet for the first time. Under the IAU definition approved on August 24, 2006, Eris is a "dwarf planet", along with objects such as Pluto, Ceres, Haumea and Makemake.<sup class="reference" id="cite_ref-IAUPressRelease2006_25-0" style="line-height:1em;">[20]

<p style="margin-top:0.4em;margin-bottom:0.5em;line-height:19.1875px;color:rgb(0,0,0);font-family:sans-serif;">In 2010, preliminary results from observations of a stellar occultation by Eris on November 6 suggested that its diameter may be only 2,326 km, which would make it essentially the same diameter as Pluto.<sup class="reference" id="cite_ref-Brown2010-occult_26-0" style="line-height:1em;">[21]  Given the error bars in the different size estimates, it is currently uncertain whether Eris or Pluto has the larger diameter.<sup class="reference" id="cite_ref-Brown2010-Plutosize_18-2" style="line-height:1em;">[15]  Both Pluto and Eris are estimated to have solid-body diameters of about 2330 km.<sup class="reference" id="cite_ref-Brown2010-Plutosize_18-3" style="line-height:1em;">[15]