Oberon (moon) geological feature on Oberon: craters and chasmata ('canyons'—deep, elongated, steep-sided depressions which would probably be described as rift valleys or escarpments if on Earth). Oberon's surface is the most heavily cratered of all the Uranian moons, with a crater density approaching saturation—when the formation of new craters is balanced by destruction of old ones. This high number of craters indicates that Oberon has the most ancient surface among Uranus's moons. The crater diameters range up to 206 kilometers for the largest known crater, Hamlet. Many large craters are surrounded by bright impact ejecta (rays) consisting of relatively fresh ice. The
Oberon (operating system) system under Plan 9 from Bell Labs was strongly inspired by the Oberon TUI. Whether the worksheet interface of the Macintosh Programmer's Workshop influenced Oberon's TUI or vice versa is difficult to decide: the Oberon System was based on Wirth's previous computer design the Lilith, and both the Apple Macintosh (and its precursor Lisa) and the Oberon System (on Ceres and its precursor Lilith) have the same roots: they were all inspired by the Alto developed at Xerox PARC. V1 was the first usable version some time before the Oberon Trilogy was published. A major change in the text model