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Space Topics: Trans-Neptunian Objects

Notable Trans-Neptunian Objects

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Since 1992, more than a thousand trans-Neptunian objects have been discovered. Most of these objects have only been seen as points of light moving across the sky, so their diameters are not well known. Therefore, it is customary when comparing these objects to list their “absolute magnitude,” a measure of the amount of light they reflect normalized to their distance from an observer. All else being equal, a brighter absolute magnitude translates to a larger diameter.

Following is a table of some of the better known trans-Neptunian objects, listed in order of their absolute magnitude. Diameters are only listed if they have been observed through a stellar occultation or through a resolved picture of the object’s disk. Trans-Neptunian objects that are officially considered to be "dwarf planets" are in bold text.

Permanent Name	Provisional Name	Absolute Magnitude	Perihelion, AU	Aphelion, AU	Inclination, Degrees	Diameter (if known), kilometers
136199 Eris	2003 UB313	-1.1	38.17	97.61	43.993	~2,400
Pluto		-1.0	30.164	48.494	17.16	2,350±50
136472 Makemake	2005 FY9	-0.2	38.666	52.809	29.0	~1,600
Haumea	2003 EL61	0.1	35.161	51.525	28.2	1,320-1,550
Charon	S/1978 P1	1.0	30.164	48.494	17.16	1,207.2
90377 Sedna	2003 VB12	1.6	76.032	928.048	11.932	~1,600
90482 Orcus	2004 DW	2.3	30.784	48.057	20.6	~1,600
50000 Quaoar	2002 LM60	2.6	41.980	45.019	8.0	1,260 +/- 190
28978 Ixion	2001 KX76	3.2	30.308	49.127	19.6
55565	2002 AW197	3.3			24.4
20000 Varuna	2000 WR106	3.7	40.804	45.210	17.2
	2004 XR190	4.5	51.038	63.780	46.735
38628 Huya	2000EB173	4.7	28.554	50.950	15.5
19521 Chaos	1998 WH24	4.9	40.925	50.376	12.1
53311 Deucalion	1999 HU11	6.6	41.579	47.157	0.4
38083 Rhadamanthus	1999 HX11	6.7	33.212	45.243	12.7
	1992 QB1	7.2	40.875	46.592	2.2