Wikijunior:Solar System/Uranus/Umbriel

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Umbriel is a moon of Uranus

Contents 1 How big is Umbriel? 2 What is its surface like? 3 How long is a day on Umbriel? 4 How long is its orbit around Uranus? 5 What is it made of? 6 How would Umbriel's gravity pull on me? 7 Who is it named after? 8 How was it discovered?

[edit] How big is Umbriel?

Umbriel is about 1169.4 km wide, or about 1/10th as wide as Earth.

[edit] What is its surface like?

The only close-up images we have of Umbriel's surface come from Voyager 2's flyby in January 1986. These images show that Umbriel has a dark surface, the darkest of any of Uranus' moons. Near the equator lies Wunda, a large ring of bright material. Wunda is assumed to be a crater, but nobody is sure what it is exactly. Near Wunda is the crater Skynd.

[edit] How long is a day on Umbriel?

One day on Umbriel is equal to about four Earth days.

[edit] How long is its orbit around Uranus?

One orbit around Uranus is also equal to about four Earth days.

[edit] What is it made of?

Umbriel is made mostly of water ice, followed by silicate rock and methane ice. Most of its methane ice is on its surface.

[edit] How would Umbriel's gravity pull on me?

If you stood on Umbriel, you would weigh about a fifth (0.23) of what you do on Earth. Someone who weighs 100 lbs on Earth would weigh only 23 lbs on Umbriel, about the weight of a dog.

[edit] Who is it named after?

Umbriel is named after the "dusky melancholy sprite" in Alexander Pope's The Rape of the Lock, and the name suggests the Latin umbra, meaning shadow.

[edit] How was it discovered?

Umbriel was discovered on October 24, 1851 by William Lassell. He also discovered the moon Ariel at the same time.