33. Rings of Uranus
In 1977 astronomers discovered that Uranus has several very narrow rings by measuring the brightness of a star as the planet moved in front of it. Voyager 2 took the first photographs of the individual rings within the uranian ring system. The rings were referred to by Greek letters or numbers after their discovery from star occultation measurements: from upper left to lower right they are named epsilon (the widest ring), delta, gamma, eta, beta, alpha, 4, 5, and 6. The Voyager photographs confirmed that at least one ring, the outermost epsilon ring, is confined by small moons in orbit close to the inner and outer edges of the ring. It is likely that the other rings have similar “shepherding satellites,” but these moons were not large enough to be detected in the Voyager images.
Voyager 2 image (Press Release P-29507).