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
Stability of the Solar System that keeps the far side of the Moon away from the Earth. Mercury is in a 3:2 spin–orbit resonance. The planets' orbits are chaotic over longer timescales, such that the whole Solar System possesses a Lyapunov time in the range of 2–230 million years. In all cases this means that the position of a planet along its orbit ultimately becomes impossible to predict with any certainty (so, for example, the timing of winter and summer become uncertain), but in some cases the orbits themselves may change dramatically. Such chaos manifests most strongly as changes in eccentricity, with some planets' orbits