Umbriel was discovered by Lassel in 1851.

Umbriel and Oberon appear quite similar though Oberon is 35% larger. All of Uranus' large moons are a mixture of about 40-50% water ice with the rest rock.

Umbriel's heavily cratered surface has probably been stable since its formation. 
It has far more and larger craters than do Ariel and Titania.

   Umbriel is very dark; it reflects only about half as much light as Ariel, 
Uranus' brightest satellite.