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2. Europa

Europa is a moon of continual fascination as it may harbor a water ocean underneath its icy crust. Europa resembles a cracked cue ball and the moon is said to be an almost perfect sphere.

Europa is 3,138 km in diameter and is 670,900 km away from Jupiter.

The cracks are actually fractures in the ice as a result of tidal flexing from Jupiter. The cracks quickly freeze over:

In false color, the cracks appear to demonstrate the mineral hematite, which is a mineral resulting from the presence of liquid water - but more data is needed to confirm:

Another piece of evidence to suggest a liquid ocean are the apparent attempts at a type of volcanism:

The ridges are a result of upward swelling liquid from underneath. Plate tectonics on Earth result in the appearance of very few meteor craters. The same result is seen on Europa. While a crater was found:

the surface is remarkably free of many impact craters. This indicates a liquid ocean as the surface must freeze over enough to cover any previous craters. The energy to keep the liquid from freezing underneath comes from two sources:

  • Tidal flexing from Jupiter

  • A warm core - the Galileo probe did detect a magnetic field which indicates a warm, metallic core

This leaves much to the imagination, but it is clear we need to send more probes to collect more data.

The prospects of life on Europa have been covered in the Astrobiology section.

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