Atlas · Pluto
The moons of Pluto
Pluto has five known moons. Charon is half as wide as Pluto itself, so the two are better thought of as a double world. Four small moons circle the pair.
Pluto and its moons
Pluto and the orbits of its five moons, to scale, seen from above Pluto’s pole.
The edge of the drawing is 70,000 km from the centre of Pluto.
How to read it
You are looking straight down on Pluto’s north pole. Pluto 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.
The drawing holds Pluto still at the centre. In truth Pluto and Charon both circle a point between them, about 2,100 km from Pluto’s centre and so outside Pluto itself, each keeping the same face to the other.
- 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.
Each orbit is a slowly turning ellipse fitted to positions from NASA’s Jet Propulsion Laboratory for the years 2000 to 2040. The list gives how far out each fit can be. Touch a row to pick out its orbit.
Charon
1 moon
Found in 1978. Mapped, with Pluto, by the New Horizons spacecraft in 2015.
| Moon | Orbit size | One orbit | Tilt | Width | Found | See it in 3D |
|---|---|---|---|---|---|---|
| Charon. Mapped by spacecraft.drawn to within 0.09° | 19,600 km | 6.39 days | 0.0° | 1,212 km | 1978 | Fly there |
The four small moons
4 moons
Found with the Hubble telescope between 2005 and 2012. They tumble as they orbit, and their years are close to 3, 4, 5 and 6 times Charon’s.
| Moon | Orbit size | One orbit | Tilt | Width | Found | See it in 3D |
|---|---|---|---|---|---|---|
| Styx. Partly seen by spacecraft.drawn to within 8° | 43,200 km | 20.16 days | 0.0° | 10.4 km | 2012 | Fly there |
| Nix. Partly seen by spacecraft.drawn to within 4° | 49,300 km | 24.85 days | 0.0° | 36 km | 2005 | Fly there |
| Kerberos. Partly seen by spacecraft.drawn to within 4° | 58,300 km | 32.17 days | 0.4° | 12 km | 2011 | Fly there |
| Hydra. Partly seen by spacecraft.drawn to within 4° | 65,200 km | 38.2 days | 0.0° | 37 km | 2005 | Fly there |
Where this comes from
- NASA/JPL Solar System Dynamics, planetary satellites: orbits fitted to JPL Horizons positions, 2000 to 2040
- NASA/JPL, planetary satellite physical parameters
- NASA/JPL, planetary satellite discovery circumstances
- NASA, Pluto’s moons
Orbit size is the average distance from the centre of Pluto. Tilt is measured from Pluto’s equator for the close moons and from the plane of the planets for the far ones, and above 90° means the moon goes round backwards.