Quaoar

Quaoar is a large trans-Neptunian object in the Kuiper belt and is classified as a dwarf planet. It orbits the Sun at a distance of about 43 astronomical units and completes an orbit roughly every 285 years. Its estimated diameter is around 1,100 kilometers, making it one of the larger known dwarf planets in the Solar System.

Discovery and naming: Quaoar was discovered in 2002 by Mike Brown, Chad Trujillo, and others using observations from Palomar and Mauna Kea. The name Quaoar comes from the Tongva creator deity, and the name was approved by the International Astronomical Union.

Physical characteristics: Observations suggest a surface that includes methane ice and other ices, with a reddish color indicating complex organic materials. The bulk density is not precisely known but is consistent with a mixture of ice and rock.

Satellite system: Quaoar has multiple natural satellites. The first moon, Weywot, was discovered in 2006 with the Hubble Space Telescope and is relatively small, orbiting the primary at a close distance. In 2011, two additional, smaller moons, Tarvos and Ijiraq, were discovered at greater distances from Quaoar. The moons help constrain the mass of Quaoar and, by extension, its density.

Orbit and dynamics: Quaoar's orbit around the Sun is characteristic of Kuiper belt objects, with a low to moderate eccentricity and modest orbital inclination. The presence of moons enables dynamical mass measurements of the system.

Significance: As one of the largest known dwarf planets in the outer Solar System, Quaoar and its moon system provide key data for understanding the formation and evolution of the Kuiper belt and dwarf-planet populations.