Data gathered by NASA’s Cassini probe as it repeatedly swept past Titan, Saturn’s largest moon, offers the best evidence yet that the smog-swaddled satellite has a substantial ocean of water sloshing beneath a thick icy crust.
During Titan’s 16-day orbit around Saturn, the distance between the moon and its planet ranges from slightly less than 1.19 million kilometres to almost 1.26 million km — a disparity that generates tides that flex the moon’s surface. Estimates of the size of those tides and their effects can provide clues about the moon’s internal structure.
Scientists looked at how Titan’s gravity – and shape – changes as it orbits Saturn, they found that gravitational tugs from the planet prompt Titan’s interior to deform in a way that suggests it has a tidal ocean beneath its icy crust – in a similar way that tugs from Earth’s moon cause tides in our seas.
The scientists calculated the liquid’s viscosity, and found it is consistent with water. The conclusion that there is a liquid layer underneath the outer icy shell is almost inescapable. Learn more here or here.