This image from the Cassini spacecraft shows a ghostly white streak,
called a spoke, in Saturn's B ring. This is the first sighting of a spoke
in nearly a year, and the first spoke seen by Cassini on the sunlit side
of the rings.
It is also the first spoke seen at high phase angle -- that is, the angle
formed between the sun, the rings and Cassini. In this geometry, the
feature appears white (instead of black) against the rings because the
very small particles comprising the spoke preferentially scatter light in
the forward direction (i.e. toward Cassini), making the spoke brighter
than the background rings.
The clear-filter image was taken in visible light with the Cassini
spacecraft wide-angle camera on July 23, 2006, at a distance of
approximately 692,000 kilometers (430,000 miles) from Saturn and at a
sun-Saturn-spacecraft, or phase, angle of 115 degrees. Image scale on the
sky at the distance of Saturn is 38 kilometers (23 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.