Editing Trans-Neptunian object (section)

== Extreme trans-Neptunian objects ==
[[File:Extreme transneptunian object eccentricity vs perihelion.png|thumb|300px|Overview of trans-Neptunian objects with extreme TNOs grouped into three categories at the top.]]
[[File:Sedna orbit.svg|thumb|upright=1.5|Sedna's orbit takes it far beyond even the Kuiper belt (30–50 AU), out to nearly 1,000 AU (Sun–Earth distance)]]
{{Main|Extreme trans-Neptunian object}}

Among the extreme trans-Neptunian objects are three high-perihelion objects classified as [[sednoid]]s: [[90377 Sedna]], {{mpl|2012 VP|113}}, and [[541132 Leleākūhonua]]. They are distant [[detached object]]s with perihelia greater than 70 AU. Their high perihelia keep them at a sufficient distance to avoid significant gravitational [[Perturbation (astronomy)|perturbations]] from Neptune. Previous explanations for the high perihelion of Sedna include a close encounter with an [[Planets beyond Neptune|unknown planet]] on a distant orbit and a distant encounter with a random star or a member of the Sun's birth cluster that passed near the Solar System.<ref name=spaceBrown>{{cite web |last=Wall |first=Mike |date=24 August 2011 |title=A Conversation With Pluto's Killer: Q & A With Astronomer Mike Brown |url=http://www.space.com/12711-pluto-killer-mike-brown-dwarf-planets-interview.html |website=[[Space.com]] |access-date=7 February 2016}}</ref><ref name=iopsciencesedna>{{cite journal |last1=Brown |first1=Michael E. |last2=Trujillo |first2=Chadwick |last3=Rabinowitz |first3=David |date=2004 |title=Discovery of a Candidate Inner Oort Cloud Planetoid |journal=[[The Astrophysical Journal]] |volume=617 |issue=1 |pages=645–649 |arxiv=astro-ph/0404456 |bibcode=2004ApJ...617..645B |doi=10.1086/422095|s2cid=7738201 }}</ref><ref name=brownsedna>{{cite web |last=Brown |first=Michael E. |date=28 October 2010 |title=There's something out there – part 2 |url=http://www.mikebrownsplanets.com/2010/10/theres-something-out-there-part-2.html |website=Mike Brown's Planets |access-date=18 July 2016}}</ref>