Atlas · Quaoar
The moon of Quaoar
Quaoar has one known moon, Weywot, found in 2006.
Quaoar and its moon
Quaoar and the orbit of its moon, to scale, seen from above the orbit.
The edge of the drawing is 21,000 km from the centre of Quaoar.
How to read it
You are looking straight down on the orbit of Weywot, from its northern side. Which way Quaoar itself is tipped is not well known, so its moon’s path is the surest thing to look down on. Quaoar is drawn to scale with the orbits. The moons are not: at this scale most would be far too small to see, so each is a dot.
Quaoar also has rings, the first of them reported in 2023. They are not drawn here yet.
- Solid dot. A spacecraft has mapped the whole surface.
- Half dot. A spacecraft has seen part of it.
- Ring. Never seen as more than a point of light.
- Pale line. Goes round the usual way, the way the planets go round the Sun: anticlockwise on these drawings.
- Amber line. Goes round backwards. 1 moon does.
Nobody has measured its size. The orbit is a slowly turning ellipse fitted to positions from NASA’s Jet Propulsion Laboratory for the years 2000 to 2030. The list gives how far out each fit can be. Touch a row to pick out its orbit.
The moon
1 moon
This is JPL’s orbit for Weywot, which rests on a handful of sightings from 2006 to 2011. JPL warns it may be poor outside those years and puts it as much as 3,600 km out by 2025, about 15° round the orbit, so the dot is a rough guide.
| Moon | Orbit size | One orbit | Tilt | Width | Found | See it in 3D |
|---|---|---|---|---|---|---|
| Weywot. Seen only as a point of light.drawn to within 0.01° | 13,500 km | 11.69 days | 154° | not measured | 2006 | Fly there |
Where this comes from
- NASA/JPL Horizons: orbit solutions for the moons of trans-Neptunian objects, fitted here over 2000 to 2030
- Braga-Ribas et al. 2013, Astrophysical Journal 773, 26 (stellar occultation)
- Morgado et al. 2023, Nature 614, 239 (the first ring)
- NASA/JPL Small-Body Database
Orbit size is the average distance from the centre of Quaoar. Tilt is measured from the plane of the planets, and above 90° means the moon goes round backwards compared with the planets.