Oberon (moon) up to 40 km and its temperature is around 180 K. However, the internal structure of Oberon depends heavily on its thermal history, which is poorly known at present. Oberon is the second-darkest large moon of Uranus after Umbriel. Its surface shows a strong opposition surge: its reflectivity decreases from 31% at a phase angle of 0° (geometrical albedo) to 22% at an angle of about 1°. Oberon has a low Bond albedo of about 14%. Its surface is generally red in color, except for fresh impact deposits, which are neutral or slightly blue. Oberon is, in fact, the reddest
Oberon (moon) Oberon is the second largest and most massive of the Uranian moons after Titania, and the ninth most massive moon in the Solar System. Oberon's density of 1.63 g/cm³, which is higher than the typical density of Saturn's satellites, indicates that it consists of roughly equal proportions of water ice and a dense non-ice component. The latter could be made of rock and carbonaceous material including heavy organic compounds. The presence of water ice is supported by spectroscopic observations, which have revealed crystalline water ice on the surface of the moon. Water ice absorption bands are stronger on Oberon's trailing