On May 1st Cassini chalked up a new Saturnian moon, its 7th discovery since the spacecraft slipped into orbit around the ringed planet on July 1, 2004. This tiny moon, provisionally named S/2005 S1, is a world just 7 kilometers (4 miles) across. It orbits within the Keeler Gap in Saturn's outer A ring. As the image above shot on May 2nd shows, the satellite's feeble gravity is strong enough to induce ripples in the rings near the edge of the gap, much the way the diminutive moon Pan does in the Encke Division. In the case of Pan, astronomers deduced the moon's mass by analyzing the scalloped-edged rings it influenced. They hope to do the same with S/2005 S1.
Counting the other provisional Saturnian moons, this new find brings the total of satellites orbiting Saturn to 50.