Saturn's moon that resembles the Death Star might harbor a vast subterranean ocean.

Strong evidence has been unearthed by astronomers, suggesting the presence of a large, youthful ocean beneath the icy surface of Saturn's miniature moon, that bears a striking resemblance to the Death Star.

A team led by French researchers examined shifts in Mimas' orbit and rotation, presenting their report on Wednesday. They believe that a concealed ocean, lying between 20 to 30 kilometers beneath the icy crust, is more plausible than an elongated rocky core. The team's conclusions were derived from the data provided by NASA's Cassini spacecraft, which scrutinized Saturn and its more than 140 moons over a decade, before plunging through the ringed planet's atmosphere in 2017, consequently disintegrating.

Mimas, while barely 400 kilometers in diameter, is heavily cratered, lacking the common indications of sub-surface activity — fractures and geysers — typical of Saturn's Enceladus and Jupiter's Europa.

"Mimas was possibly the least expected location to find a planetary ocean and, broadly speaking, liquid water," co-authoring scientist Valery Lainey from Paris Observatory stated via email. "This discovery indicates a potential world fit for habitation. However, it's still unknown how much time is necessary for life to develop."

The results of this discovery have been published in the scientific journal Nature.

According to Lainey, the ocean could fill up to half of Mimas' volume. But considering the moon's diminutive size, the ocean only corresponds to 1.2% to 1.4% of Earth's oceans. Despite its small stature, Mimas features the solar system's second-largest impact crater among any moon — the factor leading to its comparison with Star Wars' fictional space station, the Death Star.

SETI Institute's Matija Cuk and Southwest Research Institute's Alyssa Rose Rhoden were not part of the study but declared in a related editorial: "The notion that such small, icy moons may contain nascent oceans is captivating."

Estimates put the age of this concealed ocean between 5 and 15 million years, which is relatively young, leaving little trace on the moon's surface. According to Lainey, while the overall temperature of this ocean hovers just above freezing, it could be much warmer at the seafloor.

Co-author Nick Cooper from Queen Mary University of London suggested that the presence of this "surprisingly young" ocean of liquid water makes Mimas an intriguing candidate for research relating to the emergence of life.

The moon was initially discovered in 1789 by British astronomer William Herschel and was named Mimas after a giant in Greek mythology.

Emily Johnson