Moons · Jupiter

Europa: a moon with an ocean under its ice

Europa, an icy cracked moon, with Jupiter's cloud bands behind it, drawn in Exo-View

Europa is a moon of Jupiter, a little smaller than our Moon, with a smooth, cracked shell of ice and, under it, an ocean of salty liquid water that holds more water than all the Earth's oceans. It is one of the best places in the solar system to look for life. Exo-View puts it where it is now, beside Jupiter.

Fly to Europa See Jupiter

Orbit: 3.55 days round Jupiter, at 671,100 km
Width: 3,122 km, a little smaller than the Moon
Shell: Ice some tens of km thick
Ocean: Probably 60 to 150 km deep, with about twice the water of all Earth's oceans
Surface temperature: About −160 °C
Found: In January 1610 by Galileo

How we know about the ocean

The Galileo spacecraft, which orbited Jupiter from 1995 to 2003, found that Europa's magnetic field changes as Jupiter's sweeps past, as it would if a layer of salty water were beneath the ice. Its surface has few craters, so it is young and has been resurfaced, and it is covered in long cracks and ridges. Hubble has seen what may be plumes of water vapour rising from near the south pole.

Where the heat comes from

Europa is kneaded by tides. Jupiter's pull and that of its neighbours Io and Ganymede squeeze it a little differently with each orbit, and the flexing warms its inside, enough to keep water liquid so far from the Sun. On the Earth, life lives round vents on the seafloor where hot water meets rock; Europa might have the same, though no one knows.

Missions

NASA's Europa Clipper was launched in October 2024 and is due at Jupiter in 2030, to fly past Europa nearly fifty times and study the shell and ocean from above. ESA's JUICE is also on its way, and will fly by it before it settles into orbit round Ganymede. Neither will land.

In Exo-View

The button below flies from the Sun to Europa, with Jupiter looming behind it. Europa and the other three big moons are placed where they are today, so you can see which side of the planet it is on. Europa Clipper is on the Spacecraft layer.