Scientists believe that Saturn's moon Enceladus could hold a Lake Superior-sized sea underneath its icy surface.
Back in 2005, scientists speculated that perhaps there was liquid water underneath the ice on Enceladus after seeing water squirt out of "tiger stripe" cracks on the moon's south pole, but lacked the technology to find out, the Los Angeles Times reports.
But thanks to data from NASA's Cassini spacecraft, they believe that there could in fact be liquid water, thanks to gravitational evidence. Those on the Cassini mission and the Deep Space Network published their data and ideas in the journal Science.
They posit that thanks to gravitational force exerted on Enceladus by Saturn and another moon, Dione, it's possible that thanks to tidal distortion might create enough heat below the surface to allow for the existence of some liquid water.
But at the moment it's merely a hypothesis because the ice shell is 25 miles thick making it hard tell if they are right, according to Nature World News, but the gravitational pull from the southern hemisphere of the moon has lead scientists to believe something must be there.
Study author professor David J. Stevenson, of Caltech, spoke with The New York Times and said, "Then you say, 'Aha, there must be compensation.' Something more dense under the ice. The natural candidate is water."
Stevenson added, "what we've done is put forth a strong case for an ocean." And if there's an underground ocean, there could potentially be some form of life. "Material from Enceladus' south polar jets contains salty water and organic molecules, the basic chemical ingredients for life."