Saturn's Moon Mimas, also referred to as the 'Death Star' moon because of its resemblance to the Star Wars space station, may have a secret that no one knew about previously. NASA's Cassini spacecraft recently detected a strange wobble in Mimas' motion, which could indicate either a core anomaly or a hidden ocean beneath its surface. 

Scientists that analyzed the Cassini date recently published their findings in the journal Science, and if true, would be perhaps the first noteworthy discovery concerning the oft-overlooked Mimas, an icy moon with a diameter of 246 miles. It also has an 88-mile long Herschel crater which resembles the round, concave section of the Death Star and gives Mimas its nickname.

The research team that studies the most recent data on Mimas used a technique known as stereo-photogrammetry, which involves creating accurate 3D computer modeling of hundreds of different points of reference on the moon's surface. It was during this observation that the researchers noticed Mimas' 'wobble,' which was about twice are much as it should have were it a 'normal' moon. 

That wobble is what led the scientists to conclude that either the spherical moon has an elongated core (as opposed to a spherical one) or it has a liquid ocean underneath its surface ice. Such a revelation would be unexpected, though not without precedent, as both Jupiter's Europa and Saturn's own Enceladus are also both presumed to have liquid oceans under their icy surfaces.

Scientists are excited by the possibility of water on other planets or moon's because they feel this boosts the probability that life could exist in these distant oceans. They also feel that if Mimas is nearly 4 billion years old, that wobble--if caused by an oddly shaped core--would have most likely worked itself into a more spherical shape by now. 

The study concludes: "In any case, the measurement of the physical forced librations using Cassini ISS images shows surprising evidence that Mimas is more complex than we thought." 

So either way, Mimas presents a revelation that could change the way scientists look at our solar system.