Using incredibly precise measurements from NASA's Cassini
spacecraft, researchers have concluded that Saturn's biggest
moon is likely hiding a global, sub-surface water ocean, 100 km
beneath its surface. One of the most enigmatic bodies in our
solar system just got even more intriguing. Cassini has flown by
Titan more than 80 times since entering Saturn's orbit in 2004,
and its observations have confirmed that, as moons go, Titan is
a weird one. It's bigger than the planet Mercury. It's the only
moon with a real atmosphere (an atmosphere denser than Earth's,
in fact). It experiences Earthlike weather, such as rain and
snow. It's home to familiar geological features like valleys,
plains and deserts — and it's the only known object besides
Earth with standing bodies of liquid on its surface. And yet
these observations, while numerous, have all been skin deep. "In
contrast," writes planetary scientist Luciano Iess, in today's
issue of Science, "information on the moon's deep interior is
scarce." One does not sim