UCCLE, Belgium, April 25 (UPI) -- Titan, Saturn's largest moon, may have a massive liquid ocean below its surface of frozen dunes, astronomers in Belgium say.
Rose-Marie Baland and colleagues from the Royal Observatory of Belgium have analyzed seven years of data from the Cassini spacecraft as it monitored Titan's orbit and its rate of rotation.
Their theory paints a new picture of the methane-cloaked world, thought to have an atmosphere similar to that of the early Earth, the Australian Broadcasting Corp. reported Monday.
The study, to be published in the journal Astronomy and Astrophysics, said Titan's moment of inertia, the amount of energy required to stop its movement, is about 50 per cent higher than it should be for a solid body, the ABC reported. This is only possible if Titan is denser near its surface than its center, something that goes against current understanding about how planets and moons form.
The alternative possibility, the researchers said, is that Titan isn't completely solid but contains a huge ocean beneath its frozen surface of methane dunes.
Trevor Ireland from the Australian National University says he believes Baland's theory -- that Titan has a liquid layer under its solid surface -- is correct.
"If you want Titan to be in its current orbit you need to have a liquid layer to stop it from having too much spin energy," he said.
