Ariel is the fourth largest moon of the planet Uranus, with a mean radius of 579 km (360 miles) – about 0.33 times the size of our own Moon.

Ariel was discovered in 1851 by William Lassell, at the same time that he discovered Umbriel – the third largest moon of Uranus.

Ariel was visited by the Voyager 2 spacecraft in 1986.

Ariel is named after one of the spirits in the Tempest by William Shakespeare.