Now, an Underground Ocean for Titan

Saturn's moon Titan, the only moon in our solar system with a dense atmosphere, may have an ocean as well.

The conclusion is far from certain, but the argument goes like this. Titan has an elliptical orbit around Saturn, so the tidal forces to which it is subject vary over the course of its orbit. The Cassini spacecraft has flown past Titan dozens of times during its mission, providing extremely precise data on Titan's gravity and thus its size and shape. Those data show that the moon is quite flexible, more flexible than you would expect if it were rock all the way through. The most likely explanation, say the authors of the new study, is that it has an ocean of liquid water under an icy crust about 100 km (60 miles) thick.

Titan thus joins Enceladus as a good candidate for a sub-surface ocean and therefore another place to look for alien life.