What is 28978 Ixion?
{{Use dmy dates|date=July 2020}} {{Infobox Planet | image = 28978-ixion hst.jpg | symbol = [[file:Ixion symbol (bold).svg|24px]] | bgcolour=#FFFFC0 | | name=28978 Ixion | discoverer = [[Deep Ecliptic Survey]] | discovered = [[22 May]], [[2001]] | mp_name = 28978 Ixion | alt_names={{mp|2001 KX|76}} | mp_category = [[trans-Neptunian object|TNO]] ([[plutino]])<ref name=Buie>{{cite web |author=[[Marc W. Buie]] |date=12 July 2007 |title=Orbit Fit and Astrometric record for 28978 |publisher=SwRI (Space Science Department) |url=http://www.boulder.swri.edu/~buie/kbo/astrom/28978.html |access-date=29 September 2008}}</ref> |orbit_ref =<ref name=jpldata>{{cite web |date=12 July 2007 |title=JPL Small-Body Database Browser: 28978 Ixion (2001 KX76) |url=http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=Ixion |access-date=4 October 2008}}</ref> | epoch=[[31 December]], [[2006]] ([[Julian day|JD]] 2&nbsp;454&nbsp;100.5) | semimajor=5&nbsp;935.999 [[Giga|G]]m (39.680 [[Astronomical unit|AU]]) | perihelion=4&nbsp;501.495 Gm (30.091 AU) | aphelion=7&nbsp;370.503 Gm (49.269 AU) | eccentricity=0.242 | period=91&nbsp;295.847 [[day|d]] (249.95 [[Julian year (astronomy)|a]]) | inclination=19.584[[degree (angle)|°]] | asc_node=71.028° | arg_peri=298.779° | mean_anomaly=268.546° | avg_speed=4.66 km/[[second|s]] | dimensions=~650{{±|260|220}} <ref name=spitzer>{{cite arXiv |title=Physical Properties of Kuiper Belt and Centaur Objects: Constraints from Spitzer Space Telescope |author=John Stansberry, Will Grundy, Mike Brown, Dale Cruikshank, John Spencer, David Trilling, Jean-Luc Margot |work=University of Arizona, Lowell Observatory, California Institute of Technology, NASA Ames Research Center, Southwest Research Institute, Cornell University |year=2007 |eprint=astro-ph/0702538 }}</ref><br />< 822 km diameter<ref name=johnston>{{cite web|url=http://www.johnstonsarchive.net/astro/tnodiam.html |title=TNO/Centaur diameters and albedos|author=Wm. Robert Johnston }}</ref> | surface_area=< 2.24{{e|6}} k