voy2_v_bw_o_TPMBK (P-29521 BW, U-2-40, A86-7037 eq, PIA00040 eq)
“The southern hemisphere of Umbriel displays heavy cratering in this Voyager 2 image, taken Jan. 24, 1986, from a distance of 557,000 kilometers (346,000 miles). 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 similar 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 miles) 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. The Voyager project is managed for NASA by the Jet Propulsion Laboratory.”
Being from the estate of Eric Burgess, the following attached description apparently accompanied the image in one of his books:
“Figure 4-16. An early image of Umbriel taken at a distance of 650,000 miles (1.04 million km) was in color. The surface is characterized by its overall dark coloration and lack of any variations in brightness. The surface is generally grey and colorless and covered with impact craters. A bright ring near the satellite’s equator appears unique. The image reproduced here was taken later from a distance of 346,000 miles (557,000 km). It shows evidence of only minor internal activity and a surface molded mainly by impacts. The surface looks very similar to the highland areas of Earth’s Moon, the oldest parts of the lunar surface. Strangely, there are virtually no bright young craters as on the other Uranian satellites. A large crater on the terminator has a bright central peak, and the curious bright ring appears to be the wall of a large crater about 90 miles (140 km) across. The nature of this ring and its possible origin are enigmas.”
See also:
archive.org/details/AILS-A86-7037
Credit: Internet Archive website
photojournal.jpl.nasa.gov/catalog/PIA00040
Credit: JPL Photojournal website
voy2_v_bw_o_TPMBK (P-29521 BW, U-2-40, A86-7037 eq, PIA00040 eq)
“The southern hemisphere of Umbriel displays heavy cratering in this Voyager 2 image, taken Jan. 24, 1986, from a distance of 557,000 kilometers (346,000 miles). 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 similar 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 miles) 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. The Voyager project is managed for NASA by the Jet Propulsion Laboratory.”
Being from the estate of Eric Burgess, the following attached description apparently accompanied the image in one of his books:
“Figure 4-16. An early image of Umbriel taken at a distance of 650,000 miles (1.04 million km) was in color. The surface is characterized by its overall dark coloration and lack of any variations in brightness. The surface is generally grey and colorless and covered with impact craters. A bright ring near the satellite’s equator appears unique. The image reproduced here was taken later from a distance of 346,000 miles (557,000 km). It shows evidence of only minor internal activity and a surface molded mainly by impacts. The surface looks very similar to the highland areas of Earth’s Moon, the oldest parts of the lunar surface. Strangely, there are virtually no bright young craters as on the other Uranian satellites. A large crater on the terminator has a bright central peak, and the curious bright ring appears to be the wall of a large crater about 90 miles (140 km) across. The nature of this ring and its possible origin are enigmas.”
See also:
archive.org/details/AILS-A86-7037
Credit: Internet Archive website
photojournal.jpl.nasa.gov/catalog/PIA00040
Credit: JPL Photojournal website