Titania's Trenches . ... Credit Copyright: The Voyager Project , NASA Explanation: British astronomer Sir William Herschel discovered Titania and Oberon in 1787, 210 years ago today. ... Above is Voyager's highest resolution picture of Titania , Uranus' largest moon - a composite of two images recorded from a distance of 229,000 miles. ... A prominent system of fault valleys, some nearly 1,000 miles long, are visible as trench-like features near the terminator (shadow line). ...