1880 Death William Lassell, English astronomer (1st moon of Neptune), dies 1851 Event William Lassell discovers Ariel and Umbriel, satellites of Uranus 1848 Event Hyperion, moon of Saturn, discovered by Bond (U.S.) and Lassell (England) 1846 Event Neptune's moon Triton discovered by William Lassell 1799 Birthday William Lassell, discoverer, satellites of Uranus and Neptune
