S/2009 S 1
Introduction '''S/2009 S 1''' is a moonlet embedded in the outer part of Saturn's B Ring, orbiting  away from the planet. The moonlet was discovered by the ''Cassini'' Imaging Team during the Saturnian equinox event on 26 July 2009, when the ''Cassini'' spacecraft imaged the moonlet casting a -long shadow onto the B Ring. With a diameter of , it is most likely a long-lived solid body, which would count it as the smallest and innermost known moon of Saturn.
Discovery A wider perspective of the image above. S/2009 S 1 is in the center. The Cassini Division is on the right. was first identified by the ''Cassini'' Imaging Team led by Carolyn Porco, in a single image taken by the ''Cassini'' spacecraft approximately  from Saturn on 26 July 2009 11:30 UTC. The moonlet was discovered during Saturn's 2009 equinox, when it cast an approximately -long shadow on the planet's B ring.
Characteristics Based on the shadow's width, the ''Cassini'' Imaging Team infer a diameter of  for . The presence of a shadow suggests that the  is most likely a solid body large enough to have existed since the formation of the B ring. This particular moon is one of the smallest moons of Saturn that has been directly imaged. is located about  interior to the edge of the B ring, corresponding to a radial distance of  from the center of Saturn. The moonlet protrudes  above the B ring plane, which has a vertical thickness of  for comparison.Although it is embedded in the B ring,  does not appear to produce extensive, propeller-shaped disturbance features unlike the propeller moonlets in Saturn's A ring. This may be because the B ring is very dense at the moonlet's location, which would hinder the formation of visible propeller gaps around the moonlet.
See also * Moonlet* Moons of Saturn* Rings of Saturn
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