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We knew Pluto had at least five moons. The surprise is that there arenโ€™t more of them

Mark Showalter, who discovered two of Plutoโ€™s moons as the mission was making its nine-year journey, said he truly expected to find many more, as did Alan Stern, the missionโ€™s principal investigator.

Five may not be the final count, but if any more exist they were too small and too dim to see during New Horizonsโ€™ approach.

The moons are named for underworld figures in mythology.

The largest, often called a co-planet because of its size and closeness, is Charon. The others are Styx, Nix, Kerberos and Hydra.


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