Mysterious rings around Uranus point to hidden moons orbiting the ice giant

New observations of Uranus's enigmatic outer rings have shown them to be even more mysterious than astronomers had thought, and their unusual properties hint at some puzzling things going on with the planet's system of moons. These observations suggest that small, mysterious moons with surprisingly different natures are the source of the particles that make up the two outermost rings, and that there are probably even more undiscovered moons to add to the 29 already known around Uranus. Uranus 's rings are not like the bright, intricate structure of Saturn 's famous rings. Quite the contrary: Uranus' rings were only discovered in 1977 when they were noticed to block the light of background stars during stellar occultations, when Uranus was seen to move in front of a star from our point of view on Earth . Voyager 2 captured the first images of Uranus's rings when it flew past the seventh planet from the sun in January 1986, and since then the Hubble Space Telescope and the ten-meter telescopes at W. M. Keck Observatory on Mauna Kea in Hawaii have discovered further faint rings around the ice giant, bringing the total to 13. The rings are named after the Greek alphabet and the last two, outermost, rings named (𝛍) and nu (𝛎) were not discovered until a period of observations between 2003 and 2005 by a team led by the SETI Institute's Mark Showalter. The mu- and nu-rings are especially puzzling. …