Global Ocean Makes Saturn’s Moon Wobble

By examining tiny wobbles of Saturn’s moon Enceladus—whose cosmic quavers are detectable only in high-resolution images taken by NASA’s Cassini spacecraft—planetary scientists have discovered that a global ocean lies beneath the moon’s thick icy crust.

"If the surface and core were rigidly connected, the core would provide so much dead weight that the wobble would be far smaller than we observe it to be," says Matthew Tiscareno. "This proves that there must be a global layer of liquid separating the surface from the core." NASA/JPL/Space Science Institute

By examining tiny wobbles of Saturn’s moon Enceladus—whose cosmic quavers are detectable only in high-resolution images taken by NASA’s Cassini spacecraft—planetary scientists have discovered that a global ocean lies beneath the moon’s thick icy crust.

For a new study, researchers analyzed more than seven years worth of Enceladus images taken by the spacecraft, which has been orbiting Saturn since mid-2004.

Illustration of the interior of Saturn's moon Enceladus showing a global liquid water ocean between its rocky core and icy crust. Thickness of layers shown here is not to scale. NASA/JPL-Caltech