_:n35ae59186c9d4d9da9ca690c68185c37xb0
<http://schema.org/articleBody>
"Washington: Uranus may have two tiny, previously undiscovered moons orbiting near two of the planets rings, researchers using data from NASAs Voyager 2 spacecraft have found.\nRob Chancia, a doctoral student at University of Idaho in the US, spotted key patterns in the rings while examining decades-old images of Uranus icy rings taken by Voyager 2 which flew by the planet 30 years ago.\nHe noticed the amount of ring material on the edge of the alpha ring — one of the brightest of Uranus multiple rings — varied periodically. A similar, even more promising pattern occurred in the same part of the neighbouring beta ring.\nThis artists concept depicts select planetary discoveries made to date by NASAs Kepler space telescope.Credits: NASA/W. Stenzel\nWhen 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. Theres something breaking the symmetry, said Matt Hedman, an assistant professor of physics at the University of Idaho. Researchers analysed radio occultations — made when Voyager 2 sent radio waves through the rings to be detected back on Earth — and stellar occultations, made when the spacecraft measured the light of background stars shining through the rings, which helps show how much material they contain. They found the pattern in Uranus rings was similar to moon-related structures in Saturns rings called moonlet wakes.\nThe researchers estimate the hypothesised moonlets in Uranus rings would be four to 14 kilometres in diameter - as small as some identified moons of Saturn, but smaller than any of Uranus known moons. Uranian moons are especially hard to spot because their surfaces are covered in dark material. We havent seen the moons yet, but the idea is the size of the moons needed to make these features is quite small, and they could have easily been missed, Hedman said.\nThe Voyager images were not sensitive enough to easily see these moons, he said. Hedman said their findings could help explain some characteristics of Uranus rings, which are strangely narrow compared to Saturns. The moonlets, if they exist, may be acting as shepherd moons, helping to keep the rings from spreading out. Two of Uranus 27 known moons, Ophelia and Cordelia, act as shepherds to Uranus epsilon ring.\nThe problem of keeping rings narrow has been around since the discovery of the Uranian ring system in 1977 and has been worked on by many dynamicists over the years, Chancia added.\nThe research was published in the Astronomical Journal.\n"
<https://www.firstpost.com/world/uranus-may-have-two-undiscovered-moons-orbiting-near-planets-rings-study-3071348.html>