Umbriel (moon) that obliterated its older surface. Covered by numerous impact craters reaching in diameter, Umbriel is the second most heavily cratered satellite of Uranus after Oberon. The most prominent surface feature is a ring of bright material on the floor of Wunda crater. This moon, like all moons of Uranus, probably formed from an accretion disk that surrounded the planet just after its formation. The Uranian system has been studied up close only once, by the spacecraft "Voyager 2" in January 1986. It took several images of Umbriel, which allowed mapping of about 40% of the moon’s surface. Umbriel, along with
Oberon (operating system) Oberon (operating system) The Oberon System is a modular, single-user, single-process, multitasking operating system written in the programming language of the same name. It was originally developed in the late 1980s at ETH Zürich. The Oberon System has an unconventional visual Text User Interface instead of a conventional CLI or GUI. This "TUI" was very innovative in its time and influenced the design of the Acme text editor for the Plan 9 from Bell Labs operating system. The Oberon System is still maintained, but also subsequently developed into the multi-process, SMP-capable Bluebottle operating system, with a zooming user interface. The