United States Naval Observatory astronomer James Christy discovered Pluto’s largest moon.

The moon James Christy discovered was the first moon found orbiting Pluto. Christy named the moon Charon, as it was a scientific-sounding version of his wife’s nickname, “Char.” Charon itself is a rather strange moon; it’s about half the size of the planet it orbits, which is unusually large for a moon.

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