Neptune

1612

Earth based

Galileo

Galileo sees Neptune but misinterprets it, later work on his journals shows he observed it in 1612 but failed to act on the information.

1846

Earth based

Ubain Jean Joseph Leverrier

Notes Perturbations in Uranus’ orbit and accurately predicts the place of Neptune

1846

23 September

Earth based

Johanne Galle and Heinrich d'Atteste

Johanne Galle and Heinrich d'Atteste find Neptune using Leverriers results. It is later known that John Couch Adams in England produced similar results to Leverier at the same time.

1846

Earth based

Lassell

Discovery of Triton by Lasell in a retrograde orbit

1994

1995

Earth based

Hubble Space Telescope

Wide field and planetary camera are targeted on Neptune and show the dark spot has disappeared.

1989

August

Flyby

Voyager 2

Discovers 6 moons 2 shepherding the rings and a magnetic field tilted 47 degrees to axis of rotation. Brings total known rings to 11.