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Jets of water on Saturn's moon Enceladus might be an optical illusion, researchers have claimed.

Instead, they propose a more exciting explanation - the jets are actually folds in much larger 'curtains' of water erupting from the surface.

It suggests that there are more widespread ejections than thought taking place on the moon.

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Scientists in Arizona say that views of jets on the surface of Enceladus (shown on the right in this image) are actually just bright 'folds' in larger curtains (shown left) taking place on the surface. These curtains are huge walls of water stretching for hundreds of miles on the surface

The research was conducted by scientists in Arizona using data from Nasa's Cassini mission.

Images taken by the probe revealed jets on Saturn's moon, which are thought to be water from a subsurface ocean.

But, while the images had shown the jets bursting alone from points on the surface, the scientists think this view may be wrong.

They propose that there are actually long fissures on the surface where walls of water are erupting from underground,

But these cracks in the surface are not straight - they are wavy and meander across the surface for hundreds of miles.

The reason the jets appear in images is because the viewer is looking at a 'fold' in this curtain of material, the researchers said.

'We think most of the observed activity represents curtain eruptions from the "tiger stripe" fractures, rather than intermittent geysers along them,' said Dr Joseph Spitale, lead author of the study and a scientist on the Cassini mission at the Planetary Science Institute in Tucson, Arizona.

'Some prominent jets likely are what they appear to be, but most of the activity seen in the images can be explained without discrete jets.'

Enceladus icy eruptions create an illusion of discrete jets.

'We think most of the observed activity represents curtain eruptions from the "tiger stripe" fractures [illustrated], rather than intermittent geysers along them,' said Dr Joseph Spitale, lead author of the study and a scientist on the Cassini mission at the Planetary Science Institute in Tucson, Arizona

The research was conducted using data from Nasa's Cassini spacecraft, illustrated on the left. On the right, the size of Enceladus compared to the UK is shown. At about 310 miles (500km) across, Enceladus is the sixth largest moon of Saturn after Titan, Rhea, Iapetus, Dione and Tethys

The jets are believed to originate from a subsurface ocean on the moon (shown in cutaway illustration). Another recent study has revealed that this ocean may be salty, and may also drive the processes necessary for life to survive in its depths

Dr Spitale added that the direction you view the moon will play an important role in where these 'phantom jets' appear.

'If you rotated your perspective around Enceladus' south pole, such jets would seem to appear and disappear,' he said.

These phantom jets also appear to line up with features spotted in Cassini images that seem to be columns of spray.

Such curtain eruptions similarly occur on Earth where molten rock, or magma, gushes out of a deep fracture.

These eruptions, which often create spectacular curtains of fire, are seen in places such as Hawaii, Iceland and the Galapagos Islands.

'Our understanding of Enceladus continues to evolve, and we've come to expect surprises along the way,' said Dr Linda Spilker, Cassini project scientist at Nasa's Jet Propulsion Laboratory, Pasadena, California.

'This little ice world is becoming more exciting, not less, as we tease out new details about its subsurface ocean and astonishing geophysical activity.' 

Such curtain eruptions similarly occur on Earth where molten rock, or magma, gushes out of a deep fracture. These eruptions, which often create spectacular curtains of fire, are seen in places such as Hawaii, Iceland (shown) and the Galapagos Islands

'Our understanding of Enceladus [illustrated] continues to evolve, and we've come to expect surprises along the way,' said Dr Linda Spilker, Cassini project scientist at Nasa's Jet Propulsion Laboratory, Pasadena, California. 'This little ice world is becoming more exciting, not less, as we tease out new details'