Cassini spies a shadow cast by a vertically extended structure or object in the F ring in this image taken as Saturn approaches its August 2009 equinox.
The structure can be seen as a bulge near the bright core of the ring on the right of the image. Imaging scientists are working to understand the origin of structures such as this one, but they think this image shows the shadow of what appears to be a vertically extended object in the core of the F ring.
The second (bottom) version of the image has been brightened to enhance the visibility of the ring and shadow. Background stars appear elongated in the image because of the camera's exposure time.
NASA/JPL/Space Science Institute