Based on new evidence from Jupiter's moon Europa, astronomers hypothesize
that chloride salts bubble up from the icy moon's global liquid ocean and
reach the frozen surface where they are bombarded with sulfur from
volcanoes on Jupiter's largest moon, Io. The new findings propose answers
to questions that have been debated since the days of NASA's Voyager and
Galileo missions. This illustration of Europa (foreground), Jupiter (right) and Io (middle) is an artist's concept.