Triton discovered
DOI: 10.1063/PT.5.031325
On this date in 1846, just 17 days after Neptune was discovered, William Lassell discovered Triton, the largest moon of Neptune. Lassell was an amateur astronomer who made his own mirrors and was prompted to look for moons around the newly discovered planet by John Herschel. Triton is the seventh largest moon in the solar system and is the only large moon that orbits its planet in the direction opposite of the planet’s rotation. Because of this and because its composition is similar to Pluto, it may have been a dwarf planet the the Kuiper belt that was captured by Neptune’s gravity. Triton is also one of the few moons that is known to be geologically active. The image is a photomosaic created from images taken by Voyager 2 as it passed Neptune in 1989.
Date in History: 10 October 1846
