An image of the surface of Europa, taken by the Galileo spacecraft. The dark areas (called 'lenticulae' in Latin) may indicate the presence of liquid underneath.
Click on image for full size
Image courtesy of NASA
Freckles on Europa?
The surface of Europa shows many signs that there may be an ocean submerged under it's icy surface. For example, in this picture, the dimples, shown in red, may be a sign of material falling into a water layer. Another possibility is that they are produced by material rising from a moving water layer underneath. The dark spots in this picture are called "lenticulae", which is the Latin term for freckles.
Other signs of an ocean under the surface of Europa include:
* flooded terrain
* 'mushy' craters
* spreading centers
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