Ganymede

Yesterday NASA released a nifty photo of Jupiter's largest moon, Ganymede, immediately before Ganymede seems to disappear behind Jupiter. Ganymede makes a complete orbit around Jupiter every seven days, but because Ganymede's orbit is tilted, from Earth's perspective, it looks as if Jupiter's moon passes in front of Jupiter, then disappears behind the "dark side" of the massive planet, only to reappear again later. Ganymede is not nearly as tiny as the image would suggest. In fact Ganymede is larger than the planet Mercury, but Jupiter is so huge that it dwarfs Ganymede, making the moon seem tiny even though it is the largest moon in the solar system, larger even than Earth's own satellite.

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