Saturn's comparatively paper-thin rings are tilted edge on to Earth every 15 years. Because the orbits of Saturn's major satellites are in the ring plane, too, this alignment gives astronomers a rare opportunity to capture a truly spectacular parade of celestial bodies crossing the face of Saturn. Leading the parade is Saturn's giant moon Titan - larger than the planet Mercury. The frigid moon's thick nitrogen atmosphere is tinted orange with the smoggy byproducts of sunlight interacting with methane and nitrogen. Several of the much smaller icy moons that are closer in to the planet line up along the upper edge of the rings. Hubble's exquisite sharpness also reveals Saturn's banded cloud structure.