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 )
NASA has released an image of one of earth 's outer planets , Hyperion . Its bubbly appearance is due to it having a very low density for its atmosphere . Scientists about 40 per cent of the moon is made up of empty space . Hyperion has been known to contain huge bursts of charged particles .