Oberon (moon) the best images of this moon have spatial resolution of about 6 km. The images cover about 40% of the surface, but only 25% of the surface was imaged with a resolution that allows geological mapping. At the time of the flyby the southern hemisphere of Oberon was pointed towards the Sun, so the dark northern hemisphere could not be studied. No other spacecraft has ever visited the Uranian system. Oberon (moon) Oberon, also designated , is the outermost major moon of the planet Uranus. It is the second-largest and second most massive of the Uranian moons, and the ninth
IAU definition of planet moon) might be in hydrostatic equilibrium, but would still not have been defined as a component of a double planet, since the barycenter of the system lies within the more massive celestial body (the Earth). The term "minor planet" would have been abandoned, replaced by the categories "small Solar System body" (SSSB) and a new classification of "pluton". The former would have described those objects underneath the "spherical" threshold. The latter would have been applied to those planets with highly inclined orbits, large eccentricities and an orbital period of more than 200 earth years (that is, those orbiting beyond Neptune).