Astronomy Picture of the Day
September 26, 2013

Enceladus and its Plume in the Saturnshine
Enceladus and its Plume in the Saturnshine

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

Enceladus' always unusually-looking and yet extremely fascinating (but now very familiar to Planetary Scientists) huge South Polar white/blue and pink Icy-Plume, is only easily and well visible when the NASA - Cassini Spacecraft and the Sun are on opposite sides of Enceladus. But this was not the case and so, we asked ourselves: what was really lighting up this beautiful and mysterious Saturnian moon - as well as its Plume - at the time when the picture was taken? Well, the answer is simple: it was the Sunlight reflected off Saturn (---> such as the so-called "Saturnshine"). This lighting trick (actually, it would be way more correct to talk about "Lighting Geometry") was the reason that allowed the NASA - Cassini Spacecraft to capture both the back-lit Plume and the Surface of Enceladus in just one shot.

This view looks toward the Saturn-facing Hemisphere of Enceladus and North is up. The image was taken in Blue Light with the NASA - Cassini Spacecraft Narrow-Angle Camera on April 2, 2013 and it was acquired at a distance of approximately 517.000 miles (such as a little less than 832.029 Km from Enceladus and at a Sun-Enceladus-Cassini Spacecraft, or Phase, Angle of 175°. Image scale is roughly 3 miles (such as about 4,82 Km) per pixel.

This frame (which is an Original NASA - Cassini Spacecraft b/w image published on the NASA - Planetary Photojournal with the ID n. PIA 17129) has been additionally processed, contrast enhanced, magnified to aid visibility of the Surface details, Gamma corrected and then colorized, according to an educated guess carried out by Dr Paolo C. Fienga/LXTT/IPF, in what they should be its 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 Enceladus), 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 others, the existence of different Elements present on the Surface of Enceleadus, 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 Enceladus - 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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