The Kuiper Belt

Steven Dutch, Natural and Applied Sciences, University of Wisconsin - Green Bay
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The Kuiper Belt is a long-surmised and recently (1992) confirmed outer asteroid belt of rock and ice objects orbiting beyond Neptune. Many astronomers regard Pluto as merely the largest of the Kuiper Belt objects.

Kuiper Belt Objects

Data is adapted from a home page by Dave Jewitt (University of Hawaii), who discovered many of the objects listed. For such distant, faint, and slow-moving objects the data are somewhat provisional and subject to revision. Pluto is included for comparison. The table shows only the first few discovered; hundreds are now known and active researchers maintain complete tabulations.

Explanation of Table Contents

Object
Provisional designation of the object: Year of discovery followed by letter-number identifiers. None of these objects have been formally named.
a (AU)
Semi-major axis in astronomical units: 1 AU = 149.6 million km, the distance from the Earth to the Sun. The semi-major axis is half the length of the long axis of the object's orbit, and is its average distance from the Sun.
a (mil km)
Semi-major axis in millions of kilometers.
perh (mil km)
Perihelion (minimum) distance in millions of kilometers.
aph (mil km)
Aphelion (maximum) distance in millions of kilometers.
period yr.
Orbital period in years.
e
Orbital eccentricity.
i (deg)
Inclination in degrees to plane of the ecliptic.
Mag (Mr)
Magnitude at average distance.
Diam. (km)
Diameter in kilometers. Estimated from magnitude and other optical data, hence, only approximate.

Interesting Features

Note the extremely faint magnitudes of all these objects. They are almost at the limit of our ability to detect them.

Note that their orbital inclinations are mostly small. These are objects that accreted like all the planets rather than objects formed somewhere else and then perturbed into their present orbits.

1996TL66 is in a class by itself and, apart from comets, is the most distant object in the Solar System. None of the other objects listed have aphelia beyond 8000 million km.

Object a (AU) a (mil km) perh (mil km) aph (mil km) period yr. e i (deg) Mag (Mr)Diam. (km)
Pluto39.48590044407350 248.020.24917.14142400
1992 QB1446582 6122 7043 2920.072 22.8 283
1993 FW43.96567 6239 6896 2910.058 22.8 286
1993 RO39.45894 4715 7073 247 0.24 23.2 139
1993 RP39.35879 5233 6526 2460.113 24.596
1993 SB39.45894 4008 7780 2470.322 22.7 188
1993 SC39.75939 4811 7068 2500.195 21.7 319
1994 ES245.36777 6709 6845 3050.011 24.3 159
1994 EV343.16448 6190 6706 2830.042 23.3 267
1994 GV942.26313 6313 6313 274 00.1 23.1 264
1994 JQ143.36478 6478 6478 285 04 22.4 382
1994 JR139.85954 5180 6728 2510.134 22.9 238
1994 JS42.96418 4878 7958 2810.24 14 22.4 263
1994 JV39.55909 5141 6677 2480.13 17 22.4 254
1994 TB39.55909 4018 7800 2480.32 12 21.5 258
1994 TG42.36328 6328 6328 275 07 23 232
1994 TG242.56358 6358 6358 277 02 24 141
1994 TH40.96119 6119 6119 262 0 16 23 217
1994 VK843.56508 6508 6508 287 01 22 389
1995 DA236.35430 4779 6082 2190.127 23 169
1995 DB243.56508 6052 6963 2870.074 22.5 266
1995 DC245.26762 6762 6762 304 02 22.5 338
1995 GA739.55909 5200 6618 2480.124 23202
1995 GY741.36178 6178 6178 265 00.9 23.5TBD
1995 GJ42.96418 5834 70022810.091 23 22.5 301
1995 HM539.55909 4846 6973 2480.185 23.1 161
1995 KJ143.56508 6508 6508 287 03 22.5 361
1995 KK139.55909 4786 7032 2480.199 23 166
1995 FB2142.436348 6348 6348 276 01 23.5 169
1995 QY939.45894 4480 7309 2470.245 21.5TBD
1995 QZ939.85954 5001 6907 2510.16 19.5 22.5 TBD
1995WY2 45.87686265887137 3110.041.723.4TBD
1995 YY3 39.245870 4591 7150 246 0.218 0.44 23.4TBD
1996 KV1436433 6175 6690 2820.048.4 22.9 268
1996 KW146.66971 6971 6971 318 06 23.4 281
1996 KX139.55909 5318 6500 248 0.11.5 23.9 131
1996 KY139.55909 5318 6500 248 0.1 31 23.3 126
1996RQ20 39.45894 4244 7545 2470.28 38 22.6TBD
1996RR20 42.86403 6403 6403 280 05 22.8TBD
1996SZ439.45894 4598 7191 2470.225 23TBD
1996TK6642.56358 6358 6358 277 05 22 TBD
1996TL6683.812536 526519808 7670.58 24 21 500
1997CQ2944.46642 6177 7107 2960.073 22.5 TBD

Plutinos

A surprising fraction - 40 % - of Kuiper Belt objects have orbital periods close to Pluto's. 246 years is 3/2 of Neptune's period of 164 years and is a stable resonance that allows the object to avoid being perturbed by Neptune. In the asteroid belt, similarly, there are gaps where Jupiter would have 2, 5/2, or 3 times the asteroid's period but a cluster of asteroids where Jupiter has 3/2 the asteroid's period.

Kuiper Belt objects with periods close to Pluto's have been dubbed "Plutinos". A list of known plutinos from the list above follows. Pluto is included for comparison.

Object a (AU) a (mil km) perh (mil km) aph (mil km) period yr. e i (deg) Mag (Mr)Diam. (km)
Pluto39.48590044407350 248.020.24917.14142400
1993 RO39.45894 4715 7073 247 0.24 23.2 139
1993 RP39.35879 5233 6526 2460.113 24.596
1993 SB39.45894 4008 7780 2470.322 22.7 188
1993 SC39.75939 4811 7068 2500.195 21.7 319
1994 JR139.85954 5180 6728 2510.134 22.9 238
1994 JV39.55909 5141 6677 2480.13 17 22.4 254
1994 TB39.55909 4018 7800 2480.32 12 21.5 258
1995 GA739.55909 5200 6618 2480.124 23202
1995 HM539.55909 4846 6973 2480.185 23.1 161
1995 KK139.55909 4786 7032 2480.199 23 166
1995 QY939.45894 4480 7309 2470.245 21.5TBD
1995 QZ939.85954 5001 6907 2510.16 19.5 22.5 TBD
1995 YY3 39.245870 4591 7150 246 0.218 0.44 23.4TBD
1996 KX139.55909 5318 6500 248 0.11.5 23.9 131
1996 KY139.55909 5318 6500 248 0.1 31 23.3 126
1996RQ20 39.45894 4244 7545 2470.28 38 22.6TBD
1996SZ439.45894 4598 7191 2470.225 23TBD

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Created 9 June 1997, Last Update 14 December 2009

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