28978 Ixion

28978 Ixion
File:Ixion planetoid nasa.jpg
Discovered byDeep Ecliptic Survey
Discovery date22 May, 2001
MPC designation28978 Ixion
2001 KX76
TNO (plutino)[1]
Orbital characteristics[2]
Epoch December 31, 2006 (JD 2 454 100.5)
Aphelion7 370.503 Gm (49.269 AU)
Perihelion4 501.495 Gm (30.091 AU)
5 935.999 Gm (39.680 AU)
91 295.847 d (249.95 a)
4.66 km/s
Physical characteristics
Dimensions~650Script error: No such module "Su". [3]
< 822 km diameter[4]
< 2.24×10Script error: No such module "Gapnum". km²
Volume< 3.15×10Script error: No such module "Gapnum". km³
Mass≈3×10Script error: No such module "Gapnum".? kg[5]
Mean density
2.0? g/cm³
< 0.229 7? m/s²
< 0.434 6? km/s
? d
Temperature≈44 K
Spectral type
(moderately red; B-V=1.03, V-R=0.61)
19.6 (opposition)

28978 Ixion is a Kuiper belt object that was found on May 22, 2001. Ixion is a plutino (an object that has a 2:3 orbital resonance with Neptune) and could be a dwarf planet. Astronomers think that it has a diameter of about 800 km, which makes it the third biggest plutino. It is named after Ixion, a figure from Greek mythology. Before it was named Ixion, it had the provisional designation 2001 KX76.


  1. Marc W. Buie (2007-07-12). "Orbit Fit and Astrometric record for 28978". SwRI (Space Science Department). Retrieved 2008-09-29.
  2. 2.0 2.1 "JPL Small-Body Database Browser: 28978 Ixion (2001 KX76)". 2007-07-12 last obs. Retrieved 2008-10-04. Check date values in: |date= (help)
  3. John Stansberry, Will Grundy, Mike Brown, Dale Cruikshank, John Spencer, David Trilling, Jean-Luc Margot (2007). "Physical Properties of Kuiper Belt and Centaur Objects: Constraints from Spitzer Space Telescope". University of Arizona, Lowell Observatory, California Institute of Technology, NASA Ames Research Center, Southwest Research Institute, Cornell University. Retrieved 2008-11-17.CS1 maint: Multiple names: authors list (link)
  4. 4.0 4.1 Wm. Robert Johnston. "TNO/Centaur diameters and albedos".
  5. Using the 2007 Spitzer spherical radius of 325 km; volume of a sphere * an assumed density of 2 g/cm³ yields a mass (m=d*v) of 2.8E+20 kg