28978 Ixion
Hubble Space Telescope image of Ixion taken in 2006 | |
| Discovery | |
|---|---|
| Discovered by | Deep Ecliptic Survey |
| Discovery site | Cerro Tololo Obs. |
| Discovery date | 22 May 2001 |
| Designations | |
| (28978) Ixion | |
| Pronunciation | /ɪkˈsaɪ.ən/ |
Named after | Ιξίων Ixīōn |
| 2001 KX76 | |
| TNO · plutino · distant | |
| Adjectives | Ixionian /ɪksiˈoʊniən/ |
| Symbol | or (astrological) |
| Orbital characteristics | |
| Epoch 2025-05-05 (JD 2460800.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 39.88 yr (14,565 days) |
| Earliest precovery date | 17 July 1982 |
| Aphelion | 49.019 AU |
| Perihelion | 29.730 AU |
| 39.375 AU | |
| Eccentricity | 0.24494 |
| 247.076 yr (90,245 d) | |
| 293.547° | |
| 0° 0m 14.361s / day | |
| Inclination | 19.675° |
| 71.099° | |
| 2070-12-13 | |
| 300.585° | |
| Known satellites | 0 |
| Physical characteristics | |
| Dimensions | 726.84+7.06 −7.70 × 667.96+14.14 −9.92 km (projected, occultation) |
| 696.78+10.75 −8.87 km (Area equivalent) | |
| Flattening | 0.081+0.004 −0.010 (projected) |
| 12.4±0.3 h | |
| Temperature | 64+0.7 −1.1 K |
| IR (moderately red) B–V=1.009±0.051 V–R=0.61±0.03 V–I=1.146±0.086 | |
| 19.8 | |
| |
28978 Ixion (/ɪkˈsaɪ.ən/, provisional designation 2001 KX76) is a large trans-Neptunian object. It is located in the Kuiper belt, a region of icy objects orbiting beyond Neptune in the outer Solar System. Ixion is classified as a plutino, a dynamical class of objects in a 2:3 orbital resonance with Neptune. It was discovered in May 2001 by astronomers of the Deep Ecliptic Survey at the Cerro Tololo Inter-American Observatory, and was announced in July 2001. The object is named after the Greek mythological figure Ixion, who was a king of the Lapiths.
In visible light, Ixion appears dark and moderately red in color due to organic compounds covering its surface. Water ice has been suspected to be present on Ixion's surface, but may exist in trace amounts hidden underneath a thick layer of organic compounds. Ixion has a measured diameter of 697 km (433 mi), making it the fourth-largest known plutino. It appears to be a transitional object between irregularly-shaped small Solar System bodies and spherical dwarf planets. Ixion is currently not known to have a natural satellite, so its mass and density are unknown.