http://www.digitaljournal.com/tech-and-science/science/more-moons-detected-orbiting-uranus/article/478340

More moons detected orbiting Uranus

Posted Oct 28, 2016 by Tim Sandle
The number of moons around Uranus is a matter of scientific debate within the astronomy community. Despite the Voyager probe visiting the planet three decades ago, data collected is still being discussed.
Uranus as a featureless disc  photographed
by Voyager 2 in 1986
Uranus as a featureless disc, photographed by Voyager 2 in 1986
NASA
While the attention of many astronomers and astrophysicists is on the Juno probe, which is currently in orbit around Jupiter, and the Cassini probe which is gathering valuable information about Saturn, a few are still unpicking information from Voyager. In particular this relates to the gas giant Uranus and its moons.
Uranus is the seventh planet from the Sun, and the third largest. The planet has an atmosphere composed of hydrogen and helium, although the surface is likely to be made largely from "ices" formed from water, ammonia, and methane. Uranus has 27 known moons, each of which are named after characters from the works of William Shakespeare and Alexander Pope. These moons are subdivided into thirteen inner moons, five major moons and nine irregular moons.
A review of older data, by scientists from the University of Idaho that indicates that the Uranian system probably contains more moons than previously realized. One difficulty is that moons around Uranus are difficult to detect since they are formed from very dark rock (which means they reflect very little light).
The reason the scientists think there are more than 27 moons is based on observations pertaining to the planet’s rings. This is based on unexplained patterns that indicate gravitational pulls from at least one unknown object. Calculations suggest this object is between 2-9 miles in diameter. The data from Voyager, about the possible additional moon, seems to be confirmed by radio wave readings. Moreover, there could be two of these small orbiting structures.
Explaining this to Laboratory Roots, Professor Matt Hedmanm who co-leads the project looking closer at Uranus, said: “When you look at this pattern in different places around the ring, the wavelength is different — that points to something changing as you go around the ring. There's something breaking the symmetry.”
If confirmed there will need to be some discussion as to whether the body counts as an additional moon or, if it is very small, as a ‘moonlet.’ This latter outcome seems more likely and the pattern in the planet’s rings are being described as
moonlet wakes. The exact nature of the probable object won’t be realized until the next generation of high powered orbital telescopes are in operation.
The research findings will be published in a future edition of The Astronomical Journal.