File:PIA00040 Umbrielx2.47.jpg

Summary

Original Caption Released with Image: The southern hemisphere of <a href="https://en.wikipedia.org/wiki/Umbriel_(moon)" class="extiw" title="en:Umbriel (moon)">Umbriel</a> displays heavy <a href="https://en.wikipedia.org/wiki/impact_crater" class="extiw" title="en:impact crater">cratering</a> in this <a href="https://en.wikipedia.org/wiki/Voyager_2" class="extiw" title="en:Voyager 2">Voyager 2</a> image, taken Jan. 24, <a href="https://en.wikipedia.org/wiki/1986" class="extiw" title="en:1986">1986</a>, 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 <a href="https://en.wikipedia.org/wiki/Uranus_(planet)" class="extiw" title="en:Uranus (planet)">Uranus'</a> larger moons and the one that appears to have experienced the lowest level of <a href="https://en.wikipedia.org/wiki/geology" class="extiw" title="en:geology">geological</a> activity. It has a <a href="https://en.wikipedia.org/wiki/diameter" class="extiw" title="en:diameter">diameter</a> 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 <a href="https://en.wikipedia.org/wiki/Moon" class="extiw" title="en:Moon">lunar</a> 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 <a href="https://en.wikipedia.org/wiki/Terminator_(solar)" class="extiw" title="en:Terminator (solar)">terminator</a> (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 <a href="https://en.wikipedia.org/wiki/equator" class="extiw" title="en:equator">equator</a>. The nature of the ring is not known, although it might be a <a href="https://en.wikipedia.org/wiki/frost" class="extiw" title="en:frost">frost</a> 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.

The original NASA image has been modified by cropping, increasing the linear pixel density by a factor of 2.47, and converting from .TIF to .JPG format.

Licensing

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