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Watery Ocean Found Under Saturn Moon's Surface
A large water ocean has been discovered deep under the icy surface of Saturn's moon Enceladus.
The ocean, which could support life, is as big or even bigger than the largest of North America's Great Lakes, Lake Superior.
It is centred at the moon's south pole but the findings do not show if it extends to the north pole.
However, it could take up much - if not most - of Enceladus which is about 310 miles across.
The discovery was made by Italian and US scientists using the Cassini spacecraft, which has spent 10 years studying Saturn and its moons and has flown near Enceladus 19 times.
Three fly-bys between 2010 and 2012 clinched the evidence of underground water on the moon.
Scientists have said the ocean is about six miles deep and is buried beneath 18 to 24 miles of ice. On Earth, it would stretch from the South Pole up to New Zealand.
Nasa said: "The subsurface ocean evidence supports the inclusion of Enceladus among the most likely places in our solar system to host microbial life."
The discovery makes the interior of Enceladus "a very attractive potential place to look for life," said Cornell University planetary scientist Jonathan Lunine, who took part in the study.
Jupiter's much bigger moon Europa is also known to have liquid water under its surface.
Both could be possible habitats for extraterrestrial microbes, scientists believe.
The water is kept from freezing by warming tidal forces generated by the gravity of the giant gas planets that the moons orbit.
In 2005, Cassini sent back images of water vapour jetting from the surface of Enceladus.
The jets were spouting from fractures in the frozen surface known as "tiger stripes".
At the time, experts thought a large reservoir of underground water could be fuelling the plumes and now they have confirmed the presence of a subsurface ocean.