Some believe the oceans found there of carbon-enriched water are the best chance for life , outside the Earth , in our Solar System . Europa , the fourth largest moon of Jupiter , was recently discovered to have a thin oxygen atmosphere by scientists using the Hubble Space Telescope . Although Earth's atmospheric abundance of oxygen is indicative of life , astronomers speculate that Europa's oxygen arises purely from physical processes. The above picture was taken by a Voyager spacecraft in 1979, but the spacecraft Galileo is currently circling Jupiter and has been photographing Europa . The first of these pictures will be released two days from today.
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