One of the moons of Saturn could be home to underground water or possibly even a subsurface ocean, and if so, it might be friendly to life, scientists say.
“After carefully examining Mimas, we found it librates -- that is, it subtly wobbles -- around the moon’s polar axis,” Radwan Tajeddine, a Cornell research associate in astronomy and lead author of a new study in the journal Science said in a university news release.
The wobble, measured by the Cassini spacecraft, has about twice the surface displacement that scientists expected.
“We’re very excited about this measurement because it may indicate much about the satellite’s insides," Tajeddine said. "Nature is essentially allowing us to do the same thing that a child does when she shakes a wrapped gift in hopes of figuring out what’s hidden inside."
The wobble indicates there could be something lurking beneath the surface, possibly an ocean. Then again, maybe not: Tajeddine's team believes a "weirdly shaped" rocky core could also produce the same wobbling effect.
If there is an ocean below, the scientists estimate it's between 15 miles and 18 miles beneath the moon's icy surface.
Until now, Mimas was known mostly for the large Herschel Crater that makes it resemble the Death Star of the "Star Wars" movies, and many scientists believed it was basically just a big, old rock.
"People thought that this was a boring moon," Tajeddine told New Scientist.
The new study, however, puts it on the map as a place within the solar system that could hold the right conditions for some form of life.
But some scientists are already dismissing the theory.
"It's really hard to understand how an ocean could survive for billions of years inside something as small as Mimas," Francis Nimmo of the University of California, Santa Cruz, told New Scientist.
Nimmo believes there's just some bumpy rock inside the moon.