Specs
| What | Data |
|---|---|
| Name | Europa |
| Class | Galilean moon |
| Parent planet | Jupiter |
| Diameter | 3,122 km |
| Mass | 4.800 × 10²² kg |
| Distance from Jupiter | 671,100 km |
| Orbital period | 3.55 days |
| Rotation period | 3.55 days (tidally locked) |
| Surface gravity | 1.31 m/s² |
| Discovered | 1610 — Galileo Galilei |
Hidden Ocean
Europa’s defining feature is what lies beneath its surface: a global liquid water ocean, estimated to be 60–150 km deep, hidden under a shell of ice 10–30 km thick. The total volume of water is thought to be roughly twice that of all Earth’s oceans combined.
The ocean stays liquid because of tidal heating; the same gravitational squeezing from Jupiter that drives Io’s volcanism, though less extreme on Europa. Where there is liquid water and an energy source, life as we know it becomes a possibility, making Europa one of the most compelling places to search for it in the solar system.
Surface
Europa’s icy surface is one of the smoothest in the solar system, with very few craters; a sign that the ice is geologically young and continuously renewed. The surface is crossed by a vast network of reddish-brown lines called lineae: cracks in the ice filled with material welling up from below. Some regions show chaotic terrain where the ice appears to have broken apart and refrozen.
Exploration
NASA’s Europa Clipper spacecraft launched in 2024 and is set to arrive at Jupiter in 2030. It will perform dozens of close flybys of Europa to study the ocean, the ice shell, and the moon’s potential habitability; without landing.