Gazing across the ringplane, the Cassini spacecraft spots a Saturn-lit Mimas and the tiny Trojan moon Helene. Only the bright crescent on Mimas' eastern limb is lit by the Sun; the moon's night side is illuminated by Saturnshine, or "greylight" as it is called by imaging scientists.
Helene (32 kilometers, or 20 miles across) shares the orbit of Dione (not pictured here) and is visible as a speck to the left of Mimas. This view shows the Saturn-facing side of Mimas (397 kilometers, or 247 miles across).
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Nov. 2, 2005, at a distance of approximately 2 million kilometers (1.2 million miles) from Mimas and at a Sun-Mimas-spacecraft, or phase, angle of 121 degrees. Helene was about 2.2 million kilometers (1.4 million miles) distant. The image scale is 12 kilometers (7 miles) per pixel on Mimas.
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.
Credit: NASA/JPL/Space Science Institute