article: It looks, and sometimes acts, like a huge sponge floating in space. But this crumpet-like rock is in fact one of Saturn's outer moons, measuring 255 by 161 miles (410 by 260km). Named Hyperion, the moon's porous surface can be seen in incredible detail in this image taken by Cassini as it performed a flyby of the satellite. The floating bath sponge: This image shows one of Saturn's outer moons, measuring 255 by 161 miles (410 by 260km). Cassini was around 38,500 miles (62,000 km) from Hyperion when the image was taken . Hyperion is shaped like a potato and is one of the largest bodies in the solar system known to be so irregular. Its odd, almost 'bubbly' appearance, can be attributed to it having a very low density for its size, according to Nasa. This low density also means that it is composed largely of water ice with only a small amount of rock. Because of these properties the entire moon is porous, like a sponge, with well-preserved craters of various sizes packed together across its surface. Scientists believe around 40 per cent of the moon is empty space. Cassini was around 38,500 miles (62,000 km) from Hyperion when the image was taken almost a decade ago. Esa has just released a refined, false-colour perspective of the moon in which its surface features were highlighted by toning down its natural redness. During the flyby, the probe got more than it bargained for as Hyperion unleashed a burst of charged particles towards the spacecraft, effectively delivering a giant 200-volt electric shock. It appears that Hyperion's surface becomes electrostatically charged as it is bathed in charged particles. These particles are constantly streaming out into space from the sun, but Hyperion also has to deal with ones trapped within the magnetic field of its host planet, Saturn. While astronomers expected many bodies throughout the solar system to be charged, the Cassini data represents the first-ever experience of a charged natural object in space other than our moon. 'This is comparable to what happens when you rub your hair against a balloon, or when a shirt or blouse rubs against a sweater,' said Professor Tom Nordheim at University College London. Hyperion is shaped like a potato and is one of the largest bodies in the solar system known to be so irregular. Its odd, almost 'bubbly' appearance, can be attributed to it having a very low density for its size . 'The large difference in potential between the surface and the spacecraft resulted in a flow of electrons being accelerated from Hyperion toward Cassini. Hyperion is shaped like a potato and is one of the largest bodies in the solar system known to be so irregular. Its odd, almost 'bubbly' appearance, can be attributed to it having a very low density for its size. Because of these properties the entire moon is porous, like a sponge, with well-preserved craters of various sizes packed together across its surface. Scientists think that this moon is mostly made up of water ice, with small amounts of rock, and around 40 per cent of it is empty space. During the flyby, Cassini got more than it bargained for as Hyperion unleashed a burst of charged particles towards the spacecraft, effectively delivering a giant 200-volt electric shock (artist's impression pictured)
highlights: Esa has released an image of one of Saturn's outer moons, Hyperion .
  Its bubbly appearance is due to it having a very low density for its size .
  Scientists believe 40 per cent of the moon is made up of empty space .
  Hyperion has been known to unleash huge bursts of charged particles .
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