PIA11564: Shadows Big and Small
- Original Caption Released with Image:
Saturn's moon Tethys casts a shadow on the planet's A ring alongside the
larger shadow cast by the planet itself in this image taken as Saturn
approached its August 2009 equinox.
The night side of the planet is dimly lit here by ringshine. Tethys,
located off to the left of this image, is not seen. The moon Janus (179
kilometers, or 111 miles across) can be seen orbiting outside the thin F
ring at the top of the image. Other bright specks are background stars.
The novel illumination geometry created around the time of Saturn's 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
The vertical brightness on the left of the image is lens flare, an
artifact resulting from light being scattered within the camera optics.
This view looks toward the unilluminated side of the rings from about 34
degrees above the ringplane.
The image was taken in visible light with the Cassini spacecraft
wide-angle camera on June 19, 2009. The view was obtained at a distance of
approximately 1.8 million kilometers (1.1 million miles) from Saturn and
at a Sun-Saturn-spacecraft, or phase, angle of 116 degrees. Image scale is
105 kilometers (65 miles) per pixel.
The Cassini-Huygens mission is a cooperative project of NASA, the European
Space Agency and the Italian Space Agency. 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 and its two onboard cameras were designed, developed and
assembled at JPL. The imaging operations center is based at the Space
Science Institute in Boulder, Colo.
For more information about the Cassini-Huygens mission visit
http://saturn.jpl.nasa.gov/. The Cassini imaging team
homepage is at http://ciclops.org.
- Image Credit:
NASA/JPL/Space Science Institute
Image Addition Date:
Image and caption provided by the Planetary Photojournal --