The southern hemisphere of Umbriel displays heavy cratering in this NASA Voyager 2 image, taken Jan. 24, 1986. This frame is the most detailed image of Umbriel, the darkest of Uranus larger moons. http://photojournal.jpl.nasa.gov/catalog/PIA00040

Montage of Uranus five largest satellites taken by NASA Voyager 2. From to right to left in order of decreasing distance from Uranus are Oberon, Titania, Umbriel, Ariel, and Miranda.

P-29521 BW Range: 557,000 kilometers ( 346, 000 miles) The southern hemisphere of Umbriel displays heavy cratering in this Voyager 2 image. This frame, taken through the clear-filter of Voyager's narrow-angle camera, is the most detailed image of Umbriel, with a resolution of about 10 km (6 mi). Umbriel is the darkest of Uranus' larger moons and the one that appears to have experienced the lowest level of geological activity. It has a diameter of about 1,200 km (750 mi) and reflects only 16 percent of the light striking its surface; in the latter respect, Umbriel is similiar to lunar highland areas. Umbriel is heavily cratered but lacks the numerous bright-ray craters seen on the other large Uranian satellites; this results in a relatively uniform surface albedo (reflectivity). The prominent crater on the terminator (upper right) is about 110 km (70 mi) across and has a bright central peak. The strangest feature in this image (at top) is a curious bright ring, the most reflective area seen on Umbriel. The ring is about 140 km (90 mi) in diameter and lies near the satellite's equator. The nature of the ring is not known, although it might be a frost deposit, perhaps associated with an impact crater. Spots against the black background are due to 'noise' in the data.

P-29502C Range: 1.04 million kilometers (650,000 miles) This color photo of Umbriel, the darkest of Uranus' five large moons was synthesized from frames exposed with the Voyager narrow-angle camera's violet and clear filters and has a resolution of 19 km (12 mi.). Umbriel is characterized by the darkest surface and smallest brightness variations of any of the large satellites of Uranus. As seen here, the surface is also generally gray and colorless. Nevertheless, at this resolution, considerable topographic detail is revealed, showing that Umbriel's surface is covered by impact craters. The brightest spot (shown at top near the equator at approxiamately 270 ° longitude) appears as a bright ring. Its geological significance is not yet understood. Umbriel has a diameter of about 1,200 km (750 miles) and orbits 267,000 km (166,000 mi) from Uranus' center. The satellite's name, from Alexander Pope's 'Rape of the Lock,' means 'dark angel'.

New modeling shows that there likely is an ocean layer in four of Uranus' major moons: Ariel, Umbriel, Titania, and Oberon. Salty – or briny – oceans lie under the ice and atop layers of water-rich rock and dry rock. Miranda is too small to retain enough heat for an ocean layer. The modeling, detailed in a paper published in the Journal of Geophysical Research, was informed by a re-analysis of data from NASA's Voyager spacecraft. Scientists have long thought that Titania, given its size, would be most likely to retain internal heat, caused by radioactive decay. The other moons had been widely considered too small to retain the heat necessary to keep an internal ocean from freezing, especially as heating created by the gravitational pull of Uranus is only a minor source of heat. https://photojournal.jpl.nasa.gov/catalog/PIA25500

Range : 74 million km. ( 46 million miles ) P-29313CThis Voyager photograph of Uranus is a composite of for images taken by the narrow angle camera. At this range, clouds and other features in the atmosphere as small as 1,370 km. could be detected by Voyager 2. Yet, no such features are visible. This view is toward the illuminated south pole of Uranus. The predominant blue color is the result of atmospheric methane, which absorbs the red wavelengths from incoming sunlight. The spot at the upper left edge of the planet's disk reulted from the removal of a reseau mark used in making measurments on the photograph. Three of Uranus' five known satellites are visible; Miranda ( at far right, closest to the planet ), Ariel ( next out , at top), and Umbriel ( lower left ). Titania and Oberon are now outside the narrow angle camera's field of view when it centered on the planet. This color composite was made from images taken through blue, green, orange, and clear filters.