Pluto has five known moons: Charon, Nix, Hydra, Kerberos and Styx. Charon is by far the largest, while the other four are much smaller, irregularly shaped bodies discovered using powerful telescopes.
Meet Charon
Charon is about half Pluto’s diameter, an unusually large moon relative to the world it orbits. Pluto and Charon are mutually tidally locked: the same side of each faces the other, so Charon remains in approximately the same part of Pluto’s sky.
The four smaller moons
Nix and Hydra were found in 2005, Kerberos in 2011 and Styx in 2012. Their small sizes make them far harder to observe from Earth. Images from NASA’s New Horizons mission helped scientists learn more about their shapes and surfaces.
How might the moons have formed?
One leading explanation is that a collision early in Pluto’s history threw debris into orbit and some of it eventually assembled into moons. Scientists examine orbital patterns and compositions to test that scenario.
Why the names sound mythological
Pluto is named for the Roman god of the underworld, and its moons continue the underworld theme. Styx is a mythological river, while Charon is the ferryman who carried souls across it.
Frequently asked question
Is Charon bigger than Pluto?
No. Charon is large for a moon, but its diameter is about half Pluto’s.
Source and further reading
See the NASA reference for additional scientific background.
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