premise: Saturn is the second-largest moon in the Solar System.
hypothesis: Saturn is the sixth planet from the Sun and the second-largest in the Solar System , after Jupiter . Titan , Saturn 's largest moon , and the second-largest in the Solar System , is larger than the planet Mercury , although less massive , and is the only moon in the Solar System to have a substantial atmosphere . Solar System . Of the objects that orbit the Sun indirectly , the moons , two are larger than the smallest planet , Mercury.The two moons larger than Mercury are Ganymede , which orbits Jupiter , and Titan , which orbits Saturn .