CICLOPS: Cassini Imaging Central Laboratory for OPerationS
Side by Side Shadows

Side by Side Shadows
PIA 11554

Avg Rating: 9.11/10

Full Size 1004x979:
PNG 181 KB
  The moon Tethys casts its shadow on Saturn's rings next to the shadow of the planet in this image taken as Saturn approaches its August 2009 equinox.

Tethys and Saturn are off to the left of this image and are not shown. The largest of the bright specks in the image is Pandora (81 kilometers, 50 miles across). Other bright spots are background stars.

The novel illumination geometry created as Saturn approaches its August 2009 equinox allows moons orbiting in or near the plane of Saturn's equatorial rings to cast shadows onto the rings. These scenes are possible only during the few months before and after Saturn's equinox which occurs only once in about 15 Earth years. To learn more about this special time and to see movies of moons' shadows moving across the rings, see PIA11651 and PIA11660.

This view looks toward the unilluminated side of the rings from about 51 degrees above the ringplane. The image was taken in visible light with the Cassini spacecraft wide-angle camera on June 28, 2009. The view was acquired at a distance of approximately 1.5 million kilometers (932,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 78 degrees. Image scale is 88 kilometers (55 miles) per pixel.

The Cassini Equinox Mission is a joint United States and European endeavor. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The imaging team consists of scientists from the US, England, France, and Germany. The imaging operations center and team lead (Dr. C. Porco) are based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini Equinox Mission visit, and

Credit: NASA/JPL/Space Science Institute
Released: August 10, 2009 (PIA 11554)
Image/Caption Information

Alliance Member Comments
Red_dragon (Aug 10, 2009 at 2:24 PM):
Excellent image. The best is to see how the shadows of both Saturn and Tethys run parallel one to each other.
After this one, this other is a must, even more than usually:
Udanax (Aug 10, 2009 at 7:59 AM):
Congratulations for this snapshot, a preview of what I am just longing to see, provided that they are actually acquired: the wide angle images in which the shadows cast on the rings by Saturn’s moons have grown longer and longer so that they extend from one end to the other, even touching the planet itself. That should be such an inspiring vista…

(As English is not my first language, some mistakes might have been left in there despite of my attention. Please feel free to point them out).

Once we knew Saturn’s North Pole cold and blue,
Now this new season’s worth a golden hue.
A swift equinoxial tread will renew
The Sun’s equatorial travelling-through.

Rings, as it’s spring, throw a narrow shadow,
Thin as a string, tightened in a drawn bow,
Waiting for one saturnian fellow
To put in a long ebony arrow,

From an icy, half-lit, still satellite,
To an inky-black disk, devoid of light,
Quite ready, Helios in Her line of sight,
To cut through the whole rings during Her flight:

Letter D…
Let Her deep darkness swallow the tenuous coal-
Colored sheet in spiraling continuous fall,

Letter C…
Let Her seem perpendicular to empty slits
That split this see-through expanse into many bits,

Letter B…
Let Her be the stroke on soft and brittle snowflakes,
And on the pin-striped pattern left in their wakes,

Letter A…
Let Her aim Herself at the Main Rings’ border,
Where a snowplow moon stirs up quite a disorder,

Letter F…
Let Her effortlessly cut a notch in these strands,
All but featureless, kinks, knots tied by ghostly hands,

Letter G…
Let Her gingerly approach an old moon that had
It’s days, until it broke up, hanging by a thread,

Letter E…
Let Her eelish shape stand out on the enormous
Ring stamped with the initial of Enceladus,

One of the spherical icicles putting on Fall.
A straggling Sun’s setting while they lumber
Along the horizon of a light-fed South Pole
Slowly sinking into a half year long slumber…