Proper noun
Umbriel
A moon of Uranus
After the end of formation, the subsurface layer cooled, while the interior of Umbriel heated due to decay of radioactive elements present in its rocks. Source: Internet
Among Uranian moons Umbriel was least subjected to endogenic resurfacing processes, although it may like other Uranian moons have experienced a very early resurfacing event. Source: Internet
Because Uranus orbits the Sun almost on its side, and its moons orbit in the planet's equatorial plane, they (including Umbriel) are subject to an extreme seasonal cycle. Source: Internet
At the time of the flyby the southern hemisphere of Umbriel (like those of the other moons) was pointed towards the Sun, so the northern (dark) hemisphere could not be studied. Source: Internet
In 2007–2008 a number of such events were observed including two occultations of Titania by Umbriel on August 15 and December 8, 2007 as well as of Ariel by Umbriel on August 19, 2007. Source: Internet
In fact, among the Uranian moons only Oberon has more impact craters than Umbriel. Source: Internet