National Aeronautics and Space Administration Logo
Follow this link to skip to the main content NASA Banner
Solar System Exploration
Planets
Umbriel: Overview
   Back to Uranus   Overview   Gallery   Facts & Figures   News 
Image of heavily-cratered moon Umbriel.
A Voyager 2 image of Umbriel taken in 1986 from a distance of 557,000 km (346,000 miles).

Umbriel is the darkest of Uranus' largest moons. It reflects only 16 percent of the light that strikes its surface, a feature similar to the highland areas of Earth's Moon. Other Uranian moons are much brighter. The process by which Umbriel's ancient cratered surface was darkened remains a mystery.

Umbriel has a diameter of about 1,200 km (750 miles). Images taken by Voyager 2 in 1986 revealed a curious bright ring about 140 km (90 miles) in diameter on the moon's dark surface. It is unclear what created the distinctive ring, although it may be frost deposits associated with an impact crater.

Discovery:
Umbriel was discovered on 24 October 1851 by English astronomer William Lassell.

How Umbriel Got its Name:
Umbriel is named for a malevolent spirit in English poet Alexander Pope's 18th century poem "Rape of the Lock."

Moons of Uranus are named for characters in William Shakespeare's plays and from Alexander Pope's "Rape of the Lock."

Just the Facts
Orbit Size (semi-major axis):  165,285 miles
Resources
Headlines
22 Jan 2003: 
Awards and Recognition   Solar System Exploration Roadmap   Contact Us   Site Map   Print This Page
NASA Official: Kristen Erickson
Advisory: Dr. James Green, Director of Planetary Science
Outreach Manager: Alice Wessen
Curator/Editor: Phil Davis
Science Writer: Autumn Burdick
Producer: Greg Baerg
Webmaster: David Martin
> NASA Science Mission Directorate
> Budgets, Strategic Plans and Accountability Reports
> Equal Employment Opportunity Data
   Posted Pursuant to the No Fear Act
> Information-Dissemination Policies and Inventories
> Freedom of Information Act
> Privacy Policy & Important Notices
> Inspector General Hotline
> Office of the Inspector General
> NASA Communications Policy
> USA.gov
> ExpectMore.gov
> NASA Advisory Council
> Open Government at NASA
Last Updated: 12 Aug 2013