Liquid water—warmed indirectly by gravitational forces—exists on several of the solar system’s moons. Some may even contain exponentially more water than exists on Earth. While liquid water is suspected on one of Neptune’s moons, the moons of Jupiter and Saturn are closer and easier to visit. Spacecraft are slated to explore their watery worlds over the next two decades.

saturn’s conspicuous rings, made of ice particles, are shaped and fed by some of its 146 moons, including water-spewing Enceladus. Scientists think that giant Titan and tiny Enceladus are promising candidates in the search for life in Saturn’s system.

Jupiter has 95 moons, with most less than a hundred miles in diameter. The largest are the planet’s four innermost moons, first discovered by the astronomer Galileo in 1610, of which three are known to have subsurface oceans.

Liquid water—warmed indirectly by gravitational forces—exists on several of the solar system’s moons. Some may even contain exponentially more

water than exists on Earth. While liquid water is suspected on one of Neptune’s moons, the moons of Jupiter and Saturn are closer and easier to visit. Spacecraft are slated to explore their watery worlds over the next two decades.

Jupiter has 95 moons, with most less than a hundred miles in diameter. The largest are the planet’s four innermost moons, first discovered by the astronomer Galileo in 1610, of which three are known to have subsurface oceans.

saturn’s conspicuous rings, made of ice particles, are shaped and fed by some of its 146 moons, including water-spewing Enceladus. Scientists think that giant Titan and tiny Enceladus are promising candidates in the search for life in Saturn’s system.

Jason Treat, NGM Staff;

Sean McNaughton

Art: Dana Berry

Sources: Steven D. Vance,

NASA/JPL; NASA