Astronomers now believe Mimas, one of the nearly 150 moons that orbit Saturn, has a vast ocean below its cold surface.
According to authors of an article recently published in the journal Nature, the sea inside the moon formed within the last 25 million years and could make up half the natural satellite, which is estimated to be the size of California.
The theory of the deep ocean is based on data from NASA’s Cassini spacecraft, which spent more than a decade investigating the sixth planet from the Sun.
The moon’s appearance is rather bland looking, but authors stated that means, "You could have liquid water almost anywhere," Valéry Lainey, an astronomer at the Paris Observatory, said.
"By studying how the 400-kilometre-wide (250-mile-wide) Mimas wobbled in its orbit around Saturn, the researchers concluded that it had either a buried ocean or a rugby-ball-shaped core. As more scientists studied how an ocean could have formed and evolved, it became harder to explain the geology of Mimas without invoking an ocean," authors wrote.
Saturn is believed to have 146 moons that range in size from a stadium to larger than the planet Mercury.
Moons Enceladus and Titan are also believed to have underground oceans of liquid water, and a NASA mission set to launch in the 2030s is expected to examine water plumes found in the Saturnian system.
The Enceladus Orbilander is described as a flagship mission concept that will search for signs of life.
The discovery on Mimas suggests that faraway moons such as those of Uranus could also have oceans hiding beneath their crust.
Scientists said the more worlds out there that are similar to Mimas, the greater the chances of extraterrestrial life and ecosystems that’ll support living organisms.