Beneath a shell of rock-hard ice, Jupiter's moon Europa may hide an ocean with two to three times the volume of all Earth's seas combined. This episode examines the smoothest solid object known in the solar system, why its surface is only an estimated 20 to 180 million years old, and how tidal flexing driven by an orbital resonance with Io generates the internal heat that keeps that ocean liquid.

The hosts explain how the Galileo probe detected an induced magnetic field that mathematically requires a salty global conductor, why the ice shell may rotate independently of the rocky core, and how flattened craters support a thick-ice model of 10 to 30 kilometers. They then explore habitability: radiolysis producing an oxygen atmosphere, sea salts and tholins in the reddish streaks, a 2026 study suggesting the seafloor may be geologically quiet, ...