temperatures of Quaoar, unlike water ice or ethane. Both models and observations suggest that only a few larger bodies (Pluto, and ) can retain the volatile ices whereas the dominant population of small trans-Neptunian objects lost them. Quaoar, with only small amounts of methane, appears to be in an intermediary category. Ring Quaoar is the third small Solar System body known and confirmed to have a ring system, after 10199 Chariklo and 136108 Haumea. In February 2023, astronomers announced the discovery of a distant ring around Quaoar, detected in occultation observations from 2018 to 2021. The ring orbits Quaoar at a distance of , over seven times the radius of Quaoar and more than double the theoretical maximum distance of the Roche limit. The ring is not uniform but varies in radial width from , being more opaque (and denser) where it is narrow and less opaque where it is broader; it is strongly irregular around its circumference. The irregular width of Quaoar's ring resembles Saturn's F ring, which may imply the presence of small, kilometer-sized moonlets embedded within the ring and gravitationally perturbing the material. Quaoar's ring likely consists of icy particles that elastically collide with each other without accreting into a larger mass. The ring is next to the 6:1 mean-motion orbital resonance with Quaoar's moon Weywot at and Quaoar's 1:3 spin-orbit resonance at . The ring's coincidental location at these resonances implies they play a key role in maintaining the ring without having it accrete into a single moon. In particular, the confinement of rings to the 1:3 spin-orbit resonance may be common among ringed small Solar System bodies, as it has been previously seen in Chariklo and Haumea. Rotation and shape Rotational light curves of Quaoar observed on March through June 2003 gave two possible rotation periods: 8.64 hours for a single-peaked light curve by a spheroidal body, or 17.68 hours for a double-peaked light curve by an elongated ellipsoidal body. The discovery of Quaoar's ring in 2023 showed that its true rotation period should most likely be 17.68 hours in order to explain the ring's location with a stable 1:3 spin-orbit resonance. This in turn implies Quaoar should be somewhat elongated to induce such a resonance; hints of Quaoar's ellipticity have been detected in multiple occultation observations, but remain yet to be analyzed in detail. Satellite Quaoar has one known moon, Weywot (full designation (50000)