Three of Jupiter 's four great moons crossed its sunny side in January . That 's rare ; it has happened only twice in the last 15 years . There was no great scientific gain in Hubble taking the snaps . The moon is also unusually close to Earth, which means that when we look at it, our eyes are looking straight into a bright spot on one hemisphere and away from us on the other.
Three of Jupiter 's four great moons crossed its sunny side in January . That 's rare ; it has happened only twice in the last 15 years . The moon is also unusually close to Earth, which means that when we look at it, our eyes are looking straight into a bright spot on one hemisphere and away from us on the other.