AFTER a 14-year search the Hubble Space Telescope has found two tiny moons orbiting Uranus only previously seen by a planetary probe. The find supports a theory that the moonsone inside Uranus's main ring and one outsideact as "shepherds", keeping the ring from dispersing.
The Voyager 2 spacecraft discovered the moons, named Cordelia and Ophelia, as it whizzed passed the planet in January 1986. But researchers could not get a precise fix on their orbits. Even though astronomers immediately began training their telescopes on Uranus, light from the main ring blotted out the moons.
However, Philip Nicholson of Cornell University in New York State and Richard French of Wellesley College in Massachusetts began analysing images of Uranus from a range of different telescopes. They watched the ring pass in front of distant stars and spotted what looked like ripples produced by the moons, prompting the theory that the moons were ...
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