Each of the gas giants in the outer solar system are circled by rings. The rings of the outermost planet Neptune were first discovered as arcs on this day in 1984. Five years later the Voyager 2 spacecraft imaged five rings as it passed the planet. One of these rings, the Adams ring, has five arcs some of which had been the ones discovered earlier.
Voyager 2 image of the rings of Neptune. Courtesy NASA/JPL