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By in
on Oct 04, 2012

jupiter’s_moons_600

Jupiter’s moons from left to right: Io, Europa, Ganymede and Callisto. Earth’s moon is about the same size as Io. Image credit: NASA

Jupiter's moons from left to right: Io, Europa, Ganymede and Callisto. Earth's moon is about the same size as Io. Image credit: NASA