For 10 points, name this moon of Jupiter, the largest of the Galilean moons.
Geological structures on this astronomical body include the sulci ["SULL-key"] of Tiamat and Ninevah, as well as the similarly named craters of Tammuz, Osiris, and Thoth. It's not Europa, but data from the Hubble Space Telescope in 2015 observing the aurora on this body has supported the theory that this body possesses a subsurface ocean. Along with a larger body, NASA's first fly-by of this entity was on the (*) Pioneer 10 mission. This solid body has the lowest moment of inertia factor in the solar system, and its metallic core makes it the only body of its kind to possess a magnetic field. This moon exists in a 1:2:4 orbital resonance with Europa and Io. For 10 points, name this moon of Jupiter, the largest of the Galilean moons.
Geological structures on this astronomical body include the sulci ["SULL-key"] of Tiamat and Ninevah, as well as the similarly named craters of Tammuz, Osiris, and Thoth.
Ganymede