Although the surface temperature of Europa (minus 260 degrees Farenheit) is cold enough to deep freeze a standing ocean, scientists believe there may be a liquid ocean laying beneath its ice-encrusted exterior.

Heat caused by the tidal forces of Jupiter's influence may be enough to maintain a layer of liquid between Europa's core and surface.

Slightly smaller than Earth's moon, Europa has an extremely thin gaseous oxygen atmosphere produced by sunlight causing water vapor to rise from the ice on Europa's surface.