One of the big surprises: Despite the moon's cooled crust, the data shows Io maintains liquid hot lava just below the ground.

Recent flybys of the fiery world refute a leading theory of its inner structure — and reveal how little is understood about ...

Now they have the answer. Thanks to data collected by the Juno probe last winter, researchers at NASA's Jet Propulsion Laboratory (JPL) have learned that Io's volcanoes are fed by tidal flexing ...