The seventh most distant planet from the Sun, discovered by William Herschel in 1781. It is bluish green because of methane in the atmosphere. In fact the C:H ratio is 30 to 40 time the solar value. Its atmosphere is composed of hydrogen and helium, its mantle is water and ammonia ice, and its core is rocky. Uranus has 9 faint rings. Ten new satellites were discovered by Voyager 2 when it flew by in 1985. The rings of Uranus are designated 1986U2R, 6, 5, 4, , , , , , 1986U1R, and . Enhanced Voyager 2 images of the ring found it to break up into 5 major arcs of roughly equal length. Uranus has 17 known moons: Ariel, Belinda, Bianca, Cordelia, Cressida, Desdemona, Juliet, Miranda, Oberon Ophelia, Portia, Puck, Rosalind, Titania, and Umbriel. Two distant satellites in non-equatorial orbits were discovered by B. Gladman, P. Nicholson, J. A. Burns, and J. J. Kavelaars using the Palomar 5-meter telescope. The discovery was announced on Oct. 31, 1997.