Moon of Pluto
Charon
Pluto's half-size partner, locked in a mutual gaze.
Charon is half the size of Pluto, the largest moon relative to its parent anywhere in the solar system. It orbits Pluto every 6.4 days, exactly as long as Pluto takes to spin, so each always shows the other the same face. Seen from Pluto, Charon hangs motionless over one spot in the sky.
How it moves
- Charon orbits Pluto every 6.3872 days at a distance of about 19,600 km.
- Its orbit period equals both its own rotation and Pluto's, a state called mutual tidal locking.
- From Pluto's surface Charon neither rises nor sets.
- The orbit is essentially circular and lies in Pluto's equatorial plane, so the pair is tipped on its side like Uranus.
Facts
- Mean radius
- 606 km
- Mass
- 1.586e+21 kg
- Surface gravity
- 0.29 m/s²
- Rotation period
- 153.293 hours
- Orbital period
- 6.387 days
- Average orbital distance
- 19,596 km
- Eccentricity
- 0
- Discovered
- 1978, by James W. Christy (with Robert Harrington) at the U.S. Naval Observatory, Flagstaff
Seen from Pluto, Charon never rises or sets; it hovers over the same spot forever.
Sources: nssdc.gsfc.nasa.gov, ssd.jpl.nasa.gov, ssd.jpl.nasa.gov