Four moons are visible on the featured image -- can you find them all? First -- and farthest in the background -- is Titan, the largest moon of Saturn and one of the larger moons in the Solar System. The dark feature across the top of this perpetually cloudy world is the north polar hood.

If this is Saturn, where are the rings? When Saturn's "appendages" disappeared in 1612, Galileo did not understand why. Later that century, it became understood that Saturn's unusual protrusions were rings and that when the Earth crosses the ring plane, the edge-on rings will appear to disappear.