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|surfacearea=4,580,000 km² (0.898% earth)

|surfacearea=4,580,000 km² (0.898% earth)

|meantemp=53 K

|meantemp=53 K

}}'''Charon''' is the largest [[moon]] of the [[dwarf planet]] [[Pluto]]. It is so large, in fact, that some authorities hold that Pluto and Charon constitute a binary system because Pluto is not much more massive than is Charon.

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'''Charon''' is the largest [[moon]] of the [[dwarf planet]] [[Pluto]]. It is so large, in fact, that some authorities hold that Pluto and Charon constitute a binary system because Pluto is not much more massive than is Charon.

James W. Christy of the United States Naval Observatory is credited with its discovery on July 2, 1978. [[National Aeronautics and Space Administration|NASA]] hopes to obtain more extensive images of Charon and other bodies in the Pluto system with its first extensive deep-space mission to the Pluto system, ''New Horizons''.

James W. Christy of the United States Naval Observatory is credited with its discovery on July 2, 1978. [[National Aeronautics and Space Administration|NASA]] hopes to obtain more extensive images of Charon and other bodies in the Pluto system with its first extensive deep-space mission to the Pluto system, ''New Horizons''.

== Orbital and rotational characteristics ==

== Orbital and rotational characteristics ==

[[Image:Pluto3.gif|left|thumb|Pluto(center) with moon [[Charon]]. NASA image]]Charon is locked into a resonating orbit with its primary, Pluto. Its axis is not tilted, and its sidereal month and day are the same length; therefore, like the [[Moon]] of [[Earth]], Charon always presents the same face toward Pluto. Insofar as observations to date have determined, Charon's orbit is perfectly circular and in the same plane as is Pluto's equator.

[[Image:Pluto3.gif|left|thumb|Pluto(center) with moon Charon. NASA image]]Charon is locked into a resonating orbit with its primary, Pluto. Its axis is not tilted, and its sidereal month and day are the same length; therefore, like the [[Moon]] of [[Earth]], Charon always presents the same face toward Pluto. Insofar as observations to date have determined, Charon's orbit is perfectly circular and in the same plane as is Pluto's equator.

Note, however, that while Charon's revolution and rotation are technically prograde with respect to Pluto's own rotation, they are ''retrograde'' with respect to the [[Sun]]. This is because Pluto's own rotation is retrograde with respect to its own orbit.

Note, however, that while Charon's revolution and rotation are technically prograde with respect to Pluto's own rotation, they are ''retrograde'' with respect to the [[Sun]]. This is because Pluto's own rotation is retrograde with respect to its own orbit.