Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

March 3, 1996

Uranus' Moon Ariel: Valley World
Photo Credit: NASA, Voyager 2, Calvin J. Hamilton

Explanation: What formed Ariel's valleys? This question presented itself when Voyager 2 passed this satellite of Uranus in January 1986. Speculation includes that heating caused by the ancient tides of Uranus caused moonquakes and massive shifting of the moon's surface. In any event, a huge network of sunken valleys was found to cover this frozen moon, and some unknown material now coats the bottoms of many of these channels. Ariel is the second closest to Uranus outside of Miranda, and is composed of roughly half water ice and half rock. Ariel was discovered by William Lassell in 1851.

Tomorrow's picture: Uranus' Largest Moon: Titania

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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
NASA Technical Rep.: Jay Norris. Specific rights apply.
A service of: LHEA at NASA/ GSFC
&: Michigan Tech. U.