For 10 points, identify this second largest moon of Jupiter named after a nymph turned bear.
Measurements of this body's moment of inertia reveal a compact, undifferentiated silicate core which is thought by a recent study by Barr and Canup to be the result of insufficient melting during the Great Bombardment Era. The prominence of a 4.2 micrometer absorption line from surveys of this body by the NIMS spacecraft suggest it has a tenuous atmosphere of carbon dioxide which is continually replenished by sublimation of ices on its surface. This planet is also home to a(*) 1900 kilometer array of concentric rings that compose the largest impact crater system in the solar system. In addition to being home to the Valhalla crater, this body is the largest satellite in its system Â to not participate in the orbital resonance which causes the tidal heating of Io. For 10 points, identify this second largest moon of Jupiter named after a nymph turned bear.
Measurements of this body's moment of inertia reveal a compact, undifferentiated silicate core which is thought by a recent study by Barr and Canup to be the result of insufficient melting during the Great Bombardment Era.
Callisto