Europa, one of Jupiter's many moons, contains a massive subsurface ocean holding more than twice the amount of water found on Earth.

A closer look

Europa, one of Jupiter's many moons, contains a massive subsurface ocean holding more than twice the amount of water found on Earth. Beneath a crust of solid ice that is 10 to 15 miles thick, tidal heating from Jupiter's immense gravity keeps the water in a liquid state. Scientists believe this hidden ocean is one of the most promising places to look for extraterrestrial life in our solar system. We are casually sitting on a dying rock searching the stars, while an ice cube orbiting a gas giant is hoarding all the galactic drinking water. It is wonderfully depressing to think that alien life might just be a bunch of blind, frozen space-squids swimming around in absolute darkness, completely unaware that humans are sending expensive probes to take blurry photos of their icy roof. We will probably spend billions of dollars to drill through miles of ice just to find the cosmic equivalent of a glowing shrimp