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This image shows Cordelia and Ophelia along with one of Uranus' rings.
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Courtesy of NASA

Scientists Find Uranus Moons... Again?
News story originally written on March 9, 2000

Scientists just found two of Uranus' moons... again. Ophelia and Cordelia were first discovered by Voyager II in 1986. The moons are so small that they can't be detected from Earth. Scientists were tracking the tiny moons until the Hubble Space Telescope could be launched, but by the time Hubble had its sights on Uranus, Ophelia and Cordelia were lost.

So how did scientists find the lost moons? Ophelia and Cordelia are shepherding moons, which are moons that keep planetary rings together. Cordelia is just inside of one of Uranus' rings, with Ophelia following orbit on the outside. Together, they keep the particles that make up the ring in a tight loop.

"Ever since these narrow rings were found around Uranus, [we] realized that something must be holding them together," says Philip Nicholson, a professor of astronomy at Cornell, and one of the researchers who contributed to this find. "What's holding the epsilon ring together are these two moons."

Once they knew the orbits of the moons, scientists studied images from Hubble until they spotted Ophelia. Meanwhile, ripples in Uranus' rings led them to the location of Cordelia. This newest "discovery" once again names Uranus as the king of moons in our solar system with a total of 20.

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