James Christy, Co-Discoverer of Charon, Pluto’s Largest Moon

Man pointing at small dots on clear photographic plate.
June 25, 2018
CreditU.S. Naval Observatory
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Jim Christy points to the photographic plate on which he and U.S. Naval Observatory colleague Robert Harrington discovered Pluto’s largest moon, Charon, in 1978.


Jim Christy holding his original Charon discovery image in 2018.
Jim Christy in 2018.
NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Art Howard/GHSPi

Forty years after his important discovery, Jim Christy holds two of the telescope images he used to spot Pluto’s large moon Charon in June 1978. A close-up photo of Charon, taken by the New Horizons spacecraft during its July 2015 flyby, is displayed on his computer screen.