These 6 frames made up of raw images from Cassini’s narrow-angle camera show the shadow of a moon – Epimetheus, perhaps? – drifting across the Encke Gap, a 200-mile-wide channel in Saturn’s A ring kept clear by the shepherd moon Pan. The central median ringlet is just visible in these images.
With Saturn approaching its spring equinox in August, its angle to the sun is such that the rings are nearly perpendicular to its orbital plane. This causes many of the moons orbiting nearest the rings to cast their shadows directly onto the rings themselves. As the equinox draws closer the moons’ shadows will lengthen, creating more dramatic images like these.
Raw image credit: NASA/JPL/Space Science Institute. Assembled by J. Major.