Triton was discovered by British astronomer William Lassell on October 10, 1846, just 17 days after the discovery of Neptune.
When John Herschel received news of Neptune's discovery, he wrote to Lassell suggesting he search for possible moons.
Lassell did so and discovered Triton eight days later.
Lassell also claimed for a period to have discovered rings.
Although Neptune was later confirmed to have rings, they are so faint and dark that it is not plausible he actually saw them.
A brewer by trade, Lassell spotted Triton with his self-built ~61 cm (24 in) aperture metal mirror reflecting telescope (aka the "two foot" reflector).
This telescope was later donated to the Royal Observatory, Greenwich in the 1880s, but was eventually dismantled.

Triton is named after the Greek sea god Triton (Τρίτων), the son of Poseidon (the Greek god corresponding to the Roman Neptune).
The name was first proposed by Camille Flammarion in his 1880 book Astronomie Populaire, and was officially adopted many decades later.
Until the discovery of the second moon Nereid in 1949, Triton was commonly referred to as "the satellite of Neptune".
Lassell did not name his own discovery; he later successfully suggested the name Hyperion, previously chosen by John Herschel, for the eighth moon of Saturn when he discovered it.
Triton was discovered by British astronomer William Lassell on October 10, 1846, just 17 days after the discovery of Neptune. When John Herschel received news of Neptune's discovery, he wrote to Lassell suggesting he search for possible moons. Lassell did so and discovered Triton eight days later. Lassell also claimed for a period to have discovered rings. Although Neptune was later confirmed to have rings, they are so faint and dark that it is not plausible he actually saw them. A brewer by trade, Lassell spotted Triton with his self-built ~61 cm (24 in) aperture metal mirror reflecting telescope (aka the "two foot" reflector). This telescope was later donated to the Royal Observatory, Greenwich in the 1880s, but was eventually dismantled.
Triton is named after the Greek sea god Triton (Τρίτων), the son of Poseidon (the Greek god corresponding to the Roman Neptune). The name was first proposed by Camille Flammarion in his 1880 book Astronomie Populaire, and was officially adopted many decades later. Until the discovery of the second moon Nereid in 1949, Triton was commonly referred to as "the satellite of Neptune". Lassell did not name his own discovery; he later successfully suggested the name Hyperion, previously chosen by John Herschel, for the eighth moon of Saturn when he discovered it.
Triton (moon)