page_title: 50000 Quaoar
section_title: Orbit and classification
hierarchical_section_title: 50000 Quaoar / Orbit and classification
context_page_description: 50000 Quaoar is a non-resonant trans-Neptunian object and a possible dwarf planet in the Kuiper belt, a region of icy planetesimals beyond Neptune. It measures approximately 1,121 km in diameter, about half the diameter of Pluto. The object was discovered by American astronomers Chad Trujillo and Michael Brown at the Palomar Observatory on 4 June 2002. Signs of water ice on the surface of Quaoar have been found, which suggests that cryovolcanism may be occurring on Quaoar. A small amount of methane is present on its surface, which can only be retained by the largest Kuiper belt objects. In February 2007, Weywot, a synchronous moon in orbit around Quaoar, was discovered by Brown. Weywot is measured to be 170 km across. Both objects were named after mythological figures from the Native American Tongva people in Southern California. Quaoar is the Tongva creator deity and Weywot is his son.
context_section_description: Quaoar orbits the Sun at an average distance of 43.7 astronomical units (6.54×10⁹ km; 4.06×10⁹ mi), taking 288.8 years to complete one full orbit around the Sun. With an orbital eccentricity of 0.04, Quaoar follows a nearly circular orbit, only slightly varying in distance from 42 AU at perihelion to 45 AU at aphelion. At such distances, light from the Sun takes more than 5 hours to reach Quaoar. Quaoar has last passed aphelion in late 1932 and is currently approaching the Sun at a rate of 0.035 AU per year, or about 0.17 kilometers per second (380 mph). Quaoar will reach perihelion in late 2066.
  Because Quaoar has a nearly circular orbit, it does not approach close to Neptune such that its orbit can become significantly perturbed under the gravitational influence of Neptune. Quaoar's minimum orbit intersection distance from Neptune is only 12.3 AU—it does not approach Neptune within this distance over the course of its orbit, as it is not in a mean-motion orbital resonance with Neptune. Simulations by the Deep Ecliptic Survey show that the perihelion and aphelion distances of Quaoar's orbit do not change significantly over the next 10 million years; Quaoar's orbit appears to be stable over the long term.
  Quaoar is generally classified as a trans-Neptunian object or distant minor planet by the Minor Planet Center since it orbits in the outer Solar System beyond Neptune. Since Quaoar is not in a mean-motion resonance with Neptune, it is also classified as a classical Kuiper belt object (cubewano) by the Minor Planet Center and Deep Ecliptic Survey. Quaoar's orbit is moderately inclined to the ecliptic plane by 8 degrees, relatively high when compared to the inclinations of Kuiper belt objects within the dynamically cold population. Because Quaoar's orbital inclination is greater than 4 degrees, it is part of the dynamically hot population of high-inclination classical Kuiper belt objects. The high inclinations of hot classical Kuiper belt objects such as Quaoar are thought to have resulted from gravitational scattering by Neptune during its outward migration in the early Solar System.
caption: Ecliptic view of Quaoar's orbit (blue) compared to Pluto (red) and Neptune (white). The approximate perihelion (q) and aphelion (Q) dates are marked for their respective orbits.