S/2009 S 1 is a 'propeller moonlet' of Saturn orbiting at a distance of about 117,000 kilometres, in the outer part of Saturn's B Ring, and with an approximate diameter of 400 meters. It was discovered by the Cassini Imaging Team on July 26, 2009. Read more
The Cassini spacecraft captured an image of a small object in the outer portion of Saturn's B ring casting a shadow on the rings as Saturn approaches its August 2009 equinox. This new moonlet, situated about 480 kilometres, inward from the outer edge of the B ring, was found by detection of its shadow which stretches 41 kilometres, across the rings. The shadow length implies the moonlet is protruding about 200 metres, above the ring plane. If the moonlet is orbiting in the same plane as the ring material surrounding it, which is likely, it must be about 400 metres, across.