Ruddy "Freckles" on Europa
Date: 31 May 1998
Reddish spots and shallow pits pepper the enigmatic ridged surface of Jupiter's moon Europa in this view from NASA's Galileo spacecraft.
The spots and pits suggest to scientists that Europa's icy shell may be churning away like a lava lamp, with warmer ice moving upward from the bottom of the ice shell while colder ice near the surface sinks downward. Other evidence has shown that Europa likely has a deep melted ocean under its icy shell. Ruddy ice erupting onto the surface to form the lenticulae may hold clues to the composition of the ocean and to whether it could support life.
Full caption is available here.
Credit: NASA/JPL/University of Arizona/University of Colorado