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Jupiter XXIII

A small outer moon of the Jupiter system, Kalyke orbits near the outer edge of the Carme Group, a collection of irregular satellites associated with the larger moon Carme, and orbiting at distances around twenty-three million kilometres from the planet. Kalyke's distant orbit carries it around the giant planet in a period of two years and thirty-six days. Like the rest of the Carme Group, Kalyke follows a retrograde orbit around Jupiter (that is, orbiting in the opposite direction to Jupiter's rotation) which implies that the group did not form as part of the gas giant's original system of moons, but was later captured by Jupiter's gravity.

Kalyke is probably irregular in shape, with an estimated diameter of 6.9 kilometres. While all the members of the Carme Group have a reddish colouration, Kalyke is distinguished as being a considerably deeper red than the other moons in the group. While Carme and its other moons are though to have originated in a single body broken apart by Jupiter's gravity, Kalyke's distinctive colour implies that it was not originally part of that body. It may therefore represent a fragment that was captured by, or collided with, the object that would form the Carme Group, before that object in turn was captured and disrupted by Jupiter.

By convention, Jovian moons with names ending in -e indicate a retrograde irregular orbit, and Kalyke follows this convention, with a name deriving from Greek Kalyke or Calyce. There are various figures in Greek mythology who carry this name, but the moon's name is intended to refer to Calyce of Thessaly, said in some stories to have been the mother of Endymion, whose father was Zeus (the original Greek name for Jupiter).


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