Classical Kuiper belt object

A classical Kuiper belt object, also called a cubewano (/ˌkjuːbiːˈwʌnoʊ/ "QB1-o"), is a low-eccentricity Kuiper belt object (KBO) that orbits beyond Neptune and is not controlled by an orbital resonance with Neptune. Cubewanos have orbits with semi-major axes in the 40–50 AU range and, unlike Pluto, do not cross Neptune’s orbit. That is, they have low-eccentricity and sometimes low-inclination orbits like the classical planets.

The name "cubewano" derives from the first trans-Neptunian object (TNO) found after Pluto and Charon, (15760) 1992 QB1. Similar objects found later were often called "QB1-o's", or "cubewanos", after this object, though the term "classical" is much more frequently used in the scientific literature.

Objects identified as cubewanos include:

Haumea was provisionally listed as a cubewano by the Minor Planet Center in 2006, but turned out to be resonant.

Most cubewanos are found between the 2:3 orbital resonance with Neptune (populated by plutinos) and the 1:2 resonance. 50000 Quaoar, for example, has a near-circular orbit close to the ecliptic. Plutinos, on the other hand, have more eccentric orbits bringing some of them closer to the Sun than Neptune.

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