28978 Ixion

28978 Ixion is a Kuiper belt object that was found on 22 May, 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.

28978 Ixion

Discovery
Discovered by	Deep Ecliptic Survey
Discovery date	22 May, 2001
Designations
MPC designation	28978 Ixion
Alternative names	2001 KX76
Minor planet category	TNO (plutino)
Orbital characteristics
Epoch 31 December, 2006 (JD 2 454 100.5)
Aphelion	7 370.503 Gm (49.269 AU)
Perihelion	4 501.495 Gm (30.091 AU)
Semi-major axis	5 935.999 Gm (39.680 AU)
Eccentricity	0.242
Orbital period	91 295.847 d (249.95 a)
Average orbital speed	4.66 km/s
Mean anomaly	268.546°
Inclination	19.584°
Longitude of ascending node	71.028°
Argument of perihelion	298.779°
Physical characteristics
Dimensions	~650+260−220 < 822 km diameter
Surface area	< 2.24×106 km²
Volume	< 3.15×108 km³
Mass	≈3×1020? kg
Mean density	2.0? g/cm³
Surface gravity	< 0.229 7? m/s²
Escape velocity	< 0.434 6? km/s
Rotation period	? d
Albedo	0.15-0.37
Temperature	≈44 K
Spectral type	(moderately red; B-V=1.03, V-R=0.61)
Apparent magnitude	19.6 (opposition)
Absolute magnitude (H)	3.2

28978 Ixion Media

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  Ixion was discovered with the Víctor M. Blanco Telescope at the Cerro Tololo Observatory

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  Ixion imaged by the MPG/ESO telescope's Wide Field Imager at the La Silla Observatory in 2001

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  Comparison of the relative colors and sizes of the four largest plutinos and their moons

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  Different diameters for Ixion depending on its albedo

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  Comparison of sizes, albedo, and colors of various large trans-Neptunian objects. The gray arcs represent uncertainties of the object's size.