Europa is the second, and smallest, of the Galilean moons orbiting Jupiter. It measures just 3,000 km across, but this still makes it the 6th largest moon in the Solar System (Europa is just a little smaller than Earth’s moon).
Just like Io, Europa is under the influence of Jupiter’s powerful gravity, which flexes the moon as it orbits around. While this tidal flexing has caused volcanism on Io, it’s less intense on Europa. Instead, the moon seems to have liquid oceans of water surrounding the moon, encased in a shell of ice. In fact, some astronomers think that Europa might have twice as much water as all of Earth.
The surface of Europa is cracked and streaked, and almost completely devoid of craters. This means that some process is continuously resurfacing the moon. Planetary scientists have a few theories for these cracks. One idea is that volcanic water eruptions spread the ice apart, and warm water seeps out to resurface the moon. Another idea is that interior of the moon orbits faster than the ocean or shell of ice. The gravity from Jupiter can then crack the ice which has become unbalanced from the core.
With liquid water under the surface of Europa, astronomers think this could be one of the best spots in the Solar System to find life. Future missions have been developed that would eventually orbit Jupiter, and maybe even send a submarine underneath the icy surface to explore the ocean beneath.
We’ve had many stories about Europa on Universe Today, including a story about a possible submarine that could be used to explore Europa, and an article debating whether Europa’s ocean is thick or thin.