2. The largest moon of Uranus. Discovered in 1787 by William Herschel, it is composed of roughly 50% water ice, 30% silicate? rock, and 20% methane-related organic compounds. A major surface feature is a huge canyon? that dwarfs the scale of the [Grand Canyon]? on Earth and is in the same class as the [Valles Marineris]? on Mars or the [Ithaca Chasma]? on Saturn's moon Tethys.
Data for Titania: