Cassini took a series of images on Sept. 9, 2006 as it watched the bright red giant star Aldebaran slip behind Saturn's rings. This type of observation is known as a stellar occultation and uses a star whose brightness is well known.
As Cassini watches the rings pass in front, the star's light fluctuates, providing information about the concentrations of ring particles within the various radial features in the rings.
Here, Cassini watches the star through the part of the rings masked by Saturn's shadow. The view looks toward the sunlit side of the rings from about 20 degrees below the ringplane. Bright Aldebaran is over exposed, creating thin vertical lines on its image.
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Sept. 9, 2006 at a distance of approximately 351,000 kilometers (218,000 miles) from Saturn. Image scale on the sky at the distance of Saturn is 2 kilometers (1 mile) per pixel.