kupier belt objects (kbos) are comets found
The Kuiper belt
title: Kuiper belt text: within "New Horizons" fuel budget were 100%, 7%, and 97%, respectively. All were members of the "cold" (low-inclination, low-eccentricity) classical Kuiper belt, and thus very different from Pluto. PT1 (given the temporary designation "1110113Y" on the HST web site), the most favorably situated object, was magnitude 26.8, 30–45 km in diameter, and will be encountered around January 2019. Once sufficient orbital information was provided, the Minor Planet Center gave official designations to the three target KBOs: (PT1), (PT2), and (PT3). By the fall of 2014, a possible fourth target, , had been eliminated by follow-up observations. PT2 was out of title: Kuiper belt text: objects, with the surfaces of those that formed far enough from the Sun to retain HS being reddened due to irradiation. The largest KBOs, such as Pluto and Quaoar, have surfaces rich in volatile compounds such as methane, nitrogen and carbon monoxide; the presence of these molecules is likely due to their moderate vapor pressure in the 30–50 K temperature range of the Kuiper belt. This allows them to occasionally boil off their surfaces and then fall again as snow, whereas compounds with higher boiling points would remain solid. The relative abundances of these three compounds in the largest KBOs title: Comet nucleus text: probably only 100–200 meters in diameter. The largest centaurs (unstable, planet crossing, icy asteroids) are estimated to be 250 km to 300 km in diameter. Three of the largest would include 10199 Chariklo (258 km), 2060 Chiron (230 km), and the currently lost 1995 SN55 (≈300 km). Known comets have been estimated to have an average density of 0.6 g/cm. Below is a list of comets that have had estimated sizes, densities, and masses. About 80% of the Halley's Comet nucleus is water ice, and frozen carbon monoxide (CO) makes up another 15%. Much of the remainder is frozen carbon title: Kuiper belt text: Neptune during its outward migration. Since 2000, a number of KBOs with diameters of between 500 and , more than half that of Pluto (diameter 2370 km), have been discovered. 50000 Quaoar, a classical KBO discovered in 2002, is over 1,200 km across. and , both announced on July 29, 2005, are larger still. Other objects, such as 28978 Ixion (discovered in 2001) and 20000 Varuna (discovered in 2000), measure roughly across. The discovery of these large KBOs in orbits similar to Pluto's led many to conclude that, aside from its relative size, Pluto was not particularly different from other title: Kuiper belt text: is directly related to their surface gravity and ambient temperature, which determines which they can retain. Water ice has been detected in several KBOs, including members of the Haumea family such as , mid-sized objects such as 38628 Huya and 20000 Varuna, and also on some small objects. The presence of crystalline ice on large and mid-sized objects, including 50000 Quaoar where ammonia hydrate has also been detected, may indicate past tectonic activity aided by melting point lowering due to the presence of ammonia. Despite its vast extent, the collective mass of the Kuiper belt is relatively low. The total