Wednesday, April 27, 2005

New Epimetheus Image: Epimetheus: Up-Close and Colorful

CICLOPS has released this color view of Saturn's small inner moon Epimetheus, taken shortly before the T4 Titan flyby. This view was discussed here when it was posted on the JPL Raw images page. Thanks to Phil for the crater identifications.

This view shows the craters Hilairea and Pollux. Pollux in this view appears to be slightly reddish, while the rest of the moon appears slightly bluish. Normally, such color variations are the result of compositional and/or grain size variations. However, given the fact that a polarized filter was used for green,the phase angle (sun-Epimetheus-Cassini angle) at the time of the observation, and the location of the redder and bluer units, these color variations are likely the result of photmetric effects, where the color of an object can depend on the angle it is observed at. Io, which I worked quite a bit on with Galileo data, was notorious for having such color changes depending on phase angle (compare this low phase angle view from July 1999 to this view from March 1998 and then to this high phase angle view from June 1997).

This view was taken from a distance of 74,000 km and has a resolution of 450 meters/pixel, though the image has been magnified by two to aid visibility.


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