The Rings of Uranus
On March 10th 1977 rings were discovered round the planet Uranus. It came as a complete surprise. Astronomers were watching the planet pass in front of a faint star called SAO 158687, however before Uranus passed in front of the star and blocked it out, the star blinked out briefly several times. After Uranus had passed away from the star it blinked again. Astronomers discovered 6 faint rings around the planet.
When the Voyager 2 spacecraft passed by Uranus in 1986 the number of rings identified increased to 13.