Original: Galilei, G.; Sidereus Nuncius (March 13, 1610) It is the third-largest moon in the Solar System and the second largest in the Jovian system, after Ganymede.
Simplified: Galilei, G.; Sidereus Nuncius (March 13 1610) It is the second largest moon orbiting Jupiter, after Ganymede, and the third largest moon in the Solar System.