This false color image of two density waves in Saturn's A ring was made from the stellar occultation observed by Cassini's ultraviolet imaging spectrograph when the spacecraft was 6.8 million kilometers (4.2 million miles) from Saturn.
Bright areas indicate the denser regions of the rings. The bright bands in the left part of the image are the "peaks" of a density wave caused by gravitational stirring of the rings by Saturn's moon, Janus. A smaller density wave in the right half of the image is produced by the moon Pandora. The ultraviolet imaging spectrograph observed the brightness of the star Xi Ceti as the rings passed in front of it, and the flickering of the starlight was converted into the ring density depicted by the image. The image represents a distance of about 724 kilometers (450 miles), and the smallest features are about one-half mile across.