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Saturn has a total of 62 moons, which range from tiny and insignificant to giants larger than Mercury. Seven of these moons are important to the planet - the rest are tiny and don't have much importance. But one of Saturn's moons is getting some attention right now because it's snowing - onto other moons.
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Using radar evidence, scientists have discovered that the geysers on Saturn's second smallest moon (of the important seven), Enceladus, are spitting out water. This water turns to snow, then falls back onto Enceladus's surface. But the snow also makes its way to Mimas and Tethys, it's neighboring moons, and makes them more reflective. Researchers are calling this phenomena a 'snow cannon'.
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The fact that Enceladus is snowing onto other moons was discovered accidentally, when a radar from Cassini, which was aiming to penetrate the thick atmosphere of Saturn's largest moon, Titan, was also pointed at Enceladus, Mimas and Tethys with the intention of characterising their surfaces. The data showed that Mimas and Tethys were much brighter than previously thought - and the scintists realised that Enceladus was snowing.
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The radar footage of Enceladus and the other two moons also revealed that the surfaces of the three moons were extremely bright - something that cannot be explained only by snow. Scientists are guessing that the sub-surfaces of Saturn's inner moons must contain highly efficient retro-reflectors that reflect the radar waves back towards their source.
But they don't exactly know what the stuctures of the moons are. Enceladus has many pinnacles, dense cracks and ice blocks in it's surface and sub-surface, but there's no evidence that these features can be the cause of reflecting radar waves back. There are two land forms that could be responsible for reflecting the radar waves back: penitentes (which are thin blades of ice that point towards the sun) and suncups (open depressions on snowy surfaces that are reflective). But these need a lot of solar energy to form, and experts don't think that the moons are getting enough to cause them.
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Saturn's moons and rings are constantly exchaning materials, so it's not unusual for one moon to deposit matter on another moon. Nevertheless, scientists are still fascinated by this new development, and state that understanding the cause of the radar waves being reflected back could be of great use for future space travel. So, if you're planning to travel to Enceladus, Mimas or Tethys anytime soon, make sure you take a warm coat.