Umbriel at Closest Approach
Image Not Available
Photograph
Umbriel at Closest Approach
January 24, 1986
Gelatin silver print
Image: 19.4 x 24.4 cm
Overall: 20.3 x 25.4 cm
Gift of NASA and NASA Jet Propulsion Laboratory
Inscriptions verso (applied label, typed): PUBLIC INFORMATION OFFICE/ JET PROPULSION LABORATORY/ CALIFORNIA INSTITUTE OF TECHNOLOGY/ NATIONAL AERONAUTICS AND SPACE ADMINISTRATION/ PASADENA, CALIFORNIA, 91109. TELEPHONE: (818) 354-5011/ PHOTO CAPTION (TOP) P-29521 B/W/ U-2-40/ 1/17/86/ 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./ #####
