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) successful installation of Oberon System 3 to André Fischers Oberon System 3 Tutorial. An expanded version of this tutorial was published as a book, which it is out of print now. The whole book is available in electronic form under a single user license in every installed version of System 3 (Windows, Linux or Native, i.e. also with the Gadgets toolkit of OLR). More information how to get your own copy of the Oberon Companion may be found in the section of the Oberon Wikibook. Similar user Interfaces have yet to appear in more commonplace operating systems. Rob Pike's Acme