Cassini's landmark investigation of Saturn's yin-yang moon Iapetus, with
its bright and dark hemispheres, continues to provide insights into the
nature of this intriguing body.
These two views of Iapetus primarily show terrain in the southern part of
the moon's dark leading hemisphere -- the side of Iapetus that is coated
with dark material. The bright south pole of Iapetus is visible, along
with some terrain (at the bottom) that lies on the bright trailing
hemisphere.
The dark terrain known as Cassini Regio is uniformly dark between the
equator and about 30 degrees south latitude. From there down to about 50
to 60 degrees south latitude, the dark material looks "patchy" because
south-facing crater walls are bright (being largely devoid of the dark
material). South of this region, only some northward-facing crater walls
are still dark, while the bright terrain has a somewhat reddish color.
See PIA06167 for an up-close view of this transition in the northern
hemisphere.
Beyond 90 degrees south (i.e., on the trailing side), the reddish color
becomes white. The region at the bottom of the color view presented here
shows this "color boundary" in the bright terrain, which also marks the
boundary between the leading and trailing hemispheres.
Iapetus is 1,468 kilometers (912 miles) across. North is up in the
monochrome image and rotated 16 degrees to the left in the color image.
The monochrome image on the left was taken using a filter sensitive to
wavelengths of infrared light centered at 930 nanometers. The image was
obtained with the Cassini spacecraft narrow-angle camera on April 8, 2006,
at a distance of approximately 866,000 kilometers (538,000 miles) from
Iapetus and at a Sun-Iapetus-spacecraft, or phase, angle of 88 degrees.
The image scale is 5 kilometers (3 miles) per pixel.
The color view on the right was created by combining images taken in
ultraviolet, green and infrared spectral filters. The images were acquired
with the Cassini spacecraft narrow-angle camera on April 9, 2006, at a
distance of approximately 692,000 kilometers (430,000 miles) from Iapetus
and at a Sun-Iapetus-spacecraft, or phase, angle of 101 degrees. The image
scale is 4 kilometers (2.5 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/home/index.cfm. The Cassini imaging team
homepage is at http://ciclops.org.
