William Lassell (June 18th 1799 - October 5th 1880) is a British astronomer , born with Bolton in the Lancashire.

It made fortune as a brewer of Bière, which enabled him to be delivered to the passion which for him the Astronomie was. It was made build a observatory close to Liverpool, equipped with a Télescope of 60 Centimètre S, and was one of the pioneers of the use of the equatorial mountings. The mirror had been formed and polished by Lassell itself, with instruments which were also of its manufacture.

In 1846, it discovered Triton, largest satellite of Neptune, little time after the discovery of Neptune itself. In 1848, it Co-discovered Hypérion, a satellite of Saturn, independently of Bond, like Ariel and Umbriel, satellites of Uranus in 1851.

It built in 1855 another telescope, of 120 cm this time, which it installed on the island of Malta, atmospheric conditions being better there for the astronomical observation.

He was prize winner of the Gold medal of Royal Astronomical Society in 1849, of which he was president during two years starting from 1870, and of the Royal Medal in 1858.

The Astéroïde (2636) Lassell was named thus to pay homage to him, just like the crater Lassell on the the Moon, another crater on Mars and one of the rings of Neptune.

June 7th 1849 -->