The moon Rhea is pictured drifting across Saturn’s disc. Rhea is one of 3 medium sized moons (including Tethys and Dione) which are largely composed of ice with small amounts of rock and whose features consist mostly of craters. Rhea also displays the “wispy” lines that appear on Dione, so it is assumed that these are also ice cliffs as determined to be on Dione.
IMAGE NOTE: This image was not altered other than extending Saturn’s rings to fill the page on the right side. The original image was in square format so the subtle ring outlines were more cropped than seen here.