On this day in 1977, astronomers James Elliot, Ted Dunham, and Jessica Mink discovered that Uranus has rings. The discovery was made aboard the Kuiper Airborne Observatory, an airliner fitted with an infrared telescope. The researchers had planned to study the atmosphere of Uranus by observing the planet as it crossed in front of the distant star SAO 158687. To the astronomers' surprise, SAO 158687 disappeared multiple times just before and just after Uranus blocked out the star. Elliot, Dunham, and Mink concluded that a system of at least five rings was responsible. Voyager 2 and other telescopes have since delivered visual evidence of Uranus' ring system, which includes at least 13 rings.
