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	Europa At a Glance
	Discovery 1610, Galileo Galilei Diameter 1,944 miles 3,130 km Distance from Jupiter 833,400 miles 1.3 million km Orbital Period 3.6 days Compare Moons

For decades, Mars was considered the most likely home for life in the solar system. As observations continued to show a sterile, desolate world, though, scientists began turning their attention to Europa. Europa's icy crust appears to cover a large ocean of liquid water, where life may have gained a foothold.

These ‘rafts’ of ice may float atop an ocean of liquid water.

There is abundant evidence of an ocean. The Galileo spacecraft found two types of terrain that may be related to water. "Chaotic" terrain looks like icebergs breaking off glaciers on Earth. The other terrain consists of smooth plains marked by ridges that are hundreds of miles long. The ridges may form as Jupiter's gravity rips apart the thin ice sheet. In addition, the motions of salty water below the surface may generate Europa's weak magnetic field.

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