Astronomy Picture of the Day
April 21, 2015

The 'Face' of Rhea
The 'Face' of Rhea

Credits: NASA/JPL-Caltech/Space Science Institute and Dr Paolo C. Fienga/LXTT/IPF, for the additional process. and color.

The Surface Features on the Saturnian moon Rhea - mostly Impact Craters, in this image - are thrown into sharp relief thanks to long shadows. Viewing this Terrain near the Day/Night Terminator Line makes it easier to appreciate just how violent Rhea's Geological History has been. The Impact Craters on Rhea (approx. 949 miles, or about 1527,26 Km across) are the result of 4,6 Billion Years of bombardment by (relatively) small Celestial Bodies. With very little erosion, mostly due tu the so-called Space-Weathering, the Surface Scars and Craters of Rhea remained - unless they are overwritten by other, newer Impacts - almost untouched (---> intact).


This view looks toward the Anti-Saturn Hemisphere of Rhea; North is up and rotated 11° to the right (Dx). This image was taken in Visible Light with the NASA - Cassini Spacecraft's Narrow-Angle Camera on February, 10, 2015; the view was acquired at a distance of approximately 47.000 miles (such as approx. 75.638,98 Km) from the Surface of Rhea and the image scale is roughly 1500 feet (such as about 457,2 meters) per pixel.


This frame (which is an Original NASA - CASSINI Spacecraft's b/w and NON Map-Projected image published on the NASA - Planetary Photojournal with the ID n. PIA 18310) has been additionally processed, contrast enhanced, magnified, Gamma corrected and then colorized - according to an educated guess (or, if you wish, an informed speculation) carried out by Dr Paolo C. Fienga - in Absolute Natural Colors (such as the colors that a human eye would actually perceive if someone were onboard the NASA - Cassini Spacecraft and then looked outside, towards the Saturnian moon "Rhea"), by using an original technique created - and, in time, dramatically improved - by the Lunar Explorer Italia Team. Different colors, as well as different shades of the same color, mean, among other things, the existence of different Elements (Minerals) present on the Surface of Rhea, each having a different Albedo (---> Reflectivity) and Chemical Composition.


Note: it is possible (but we, as IPF, have no way to be one-hundred-percent sure of such a circumstance), that the actual luminosity of Rhea- as it is in this frame - would appear, to an average human eye, a little bit lower than it has been shown (or, better yet: interpreted) here.



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