The icy moon Enceladus is what's spewing water on Saturn forming a ring around the planet, scientists have found.

"There is no analogy to this behavior on Earth," said Paul Hartogh of Max-Planck-Institut für Sonnensystemforschung, the scientist who led the analysis that yielded the odd results.

Hartogh and others examined information from European Space Agency's (ESA) Herschel space observatory and determined that Enceladus, the sixth largest moon of Saturn, is raining water vapors that form a huge donut-shaped ring around Saturn.

Enceladus is responsible for Saturn's water source in the upper atmosphere. It is the only moon in the Solar System known to affect the chemical composition of its parent planet.

For 14 years planetary scientists have pondered the answer to this mystery, and believe they've finally found it.

Enceladus rains around 550 pounds (250 kilograms) of water vapor every second, according to ESA. It does this through a set of jets from the south polar region, known as the Tiger Stripes because of their unique surface markings.

With this amount of water being expelled, vapors can get through to Saturn regardless of some being lost in space, or falling to other Saturn moons, and freezing on Saturn's rings. Some 3 to 5 percent of the water emitted by Enceladus ends up falling into Saturn.

"The reason why so much water is produced is not clear," Hartogh told 3News. "Of course you have this warm area in the south - and that is probably created by some tidal forces - but the exact mechanism is not known. The amount of energy dissipating due to tidal forces is actually not enough to explain why so much water is produced there."

The exact origin of the water and why it spews from Enceladus is unclear. 

One hypothesis is that the vapor comes from an underground of reservoir of saltwater in Enceladus, according an analysis by Frank Postberg of Heidelberg University, reported Scientific American.

"Herschel has proved its worth again. These are observations that only Herschel can make," said Göran Pilbratt, ESA Herschel Project Scientist.

Enceladus was first discovered in 1789 by William Herschel, but little was known about it until recent years.