The Kuiper Belt objects are trans-Neptunian asteroid-like objects. (1) They can be found 30 to 50 AU away from the sun. (1) They are most likely covered in frozen water. We believe they are proto-short period comets made from remnant matter from the early accretional phases during the formation of the solar system. (1) There appears to be over 70,000 (and maybe as much as 100,000 (5)) of these asteroid-like objects outside the orbit of Neptune. (2) Astronomers have found close to 500 KBOs. (2) There seems to be three different classes of KBOs, the Plutinos, the Classical KBOs and the Scattered KBOs. (5)

Plutinos orbit the sun for 2 orbits when Neptune takes 3 orbits, the same as the planet Pluto. (2) This seems to stabilize them against gravitational perturbations by Neptune. (2) Classical KBOs are the majority of the KBOs and have small eccentricities in their orbits and maintain large separations from Neptune. (2) Scattered KBOs “possess large, eccentric, inclined orbits that have perihelion distances near q = 35 AU” (Jewitt ,2) which allow Neptune to exert weak control over their orbits. (2)

The largest known object in the Kuiper Belt is Quaoar (LM60). It is 1300km in diameter and circles the sun ever 288 years. (7) Quaoar (pronounced KWAH-o-ar) is named after the creation god of the Tongva tribe in southern California near where Caltech is located. The second largest is object designated AW197. (2) The third largest known object in the Kuiper Belt is provisional designation KX76, known as Ixion. It is 1200m across, roughly the size of Pluto’s moon, Charon. (2) The fourth largest object is called Varuna, provisional designation WR106. It is about 900m across. (2) (sorry for mixing up the units)

The planet Pluto and its moon, Charon, have been accused of having been pulled from the Kuiper Belt via the gravitational pull of Neptune and the other three gas giants. Neptune’s moon, Triton, has been suspected to be pulled from the Kuiper Belt because its composition differs from neighboring objects. (3) These would be the largest of possible Kuiper Belt objects. (4)

We also believe the Centaurs are from the Kuiper Belt. The Centaurs are comet-like objects in unstable planet crossing orbits. “With orbital lifetimes that are far shorter than the age of the solar system, the Centaurs could not have formed where they currently are found. “ (Jewitt, 3)

As of April 2002, a new class of Kuiper Belt Objects have been found. These objects are dim and travel in pairs. So far a total of seven pairs of these KBOs have been found. They are 5,000 times less massive than Pluto. (info thanks to CapnTrippy) Because they appear 'dim', I propose their surface is low in frozen water content.

(1) IvyNeko Kuiper
17 Feb 20002
(2) David Jewitt. Kuiper Belt. University of Hawaii
07 OCT 2002
(3) Jane X. Luu and David C. Jewitt. The Kuiper Belt:May 1996. Scientific American.
17 Feb 2002
(4) Bill Arnett. Kuiper-Oort. University of California, Santa Barbara
5 Mar 2002
(5) Richard Kowalski. Exploring the Kuiper Belt. Quail Hollow Observatory.
5 Mar 2002
(6) NASA & Veillet. Hubble Hunts Down Binary Objects. Space Telescope Science Institute.
22 APR 2002.
(7) Richard Stenger. Biggest object since Pluto found in solar system.
07 OCT 2002.

note: I used everything2 in my bibliography and the professor accepted it! Info added/changed due to Quaoar.