22 August

1989: On 22 August 1989, it was discovered that the planet Neptune had a ring system.

Voyager 2 had taken images of Neptune on 20 August 1989, five days before its closest encounter with the planet on 25 August. Voyager 2's images showed the rings to be complete but with bright clumps. Like Uranus and Jupiter, Neptune's rings are very dark but their composition is unknown.