Science & Exploration 11 January 1243 views 4 likes ESA / Science & Exploration / Space Science 1787: On 11 January 1787, Sir William Herschel discovered Titania, the first moon of Uranus. Six years earlier, he had discovered the planet. Titania's diameter is 1610 kilometres and its distance from Uranus is 436 300 kilometres. Like Thank you for liking You have already liked this page, you can only like it once!