Astronomy Picture of the Day
January 5, 2015

Bright Crescent, Dark Rings
Bright Crescent, Dark Rings

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

Saturn's Main Rings, as seen here on their "lit" (---> illuminated) "face", appear to the Viewer, in this case, much darker than the usual.

Why? That's because they tend to scatter light back toward its source, such as the Sun. Usually, when taking images of the Rings in Geometries like this one, the exposures times are increased to make the Rings more visible. Here, the requirement to not over-expose Saturn's Lit Crescent reveals just how dark the Rings actually become (---> are). Scientists are interested in images in this Sunward-facing (---> also known as "High Phase") Geometry because the way that the Rings scatter the Sunlight can tell us much about the Ring Particles' Physical make-up.

This view looks toward the Sunlit Side of the Rings, from about above the Ring-Plane. The image was taken in Visible Light with the NASA - Cassini Spacecraft Wide-Angle Camera on January 12, 2014. The view was acquired at a distance of approximately 1,4 Million Miles (such as approx. 2.253.076 Million KiloMeters) from Saturn and at a Sun-Saturn-NASA - Cassini Spacecraft, or Phase, Angle of 152°. Image scale here is roughly 86 miles (such as approx. 138,4 Km) per pixel.

This frame (which is an Original NASA - Cassini Spacecraft b/w frame published on the NASA - Planetary Photojournal with the ID n. PIA 18294) has been additionally processed, contrast enhanced, magnified to aid visibility of the details of the Saturnian Atmosphere and then colorized, according to an educated guess carried out by Dr Paolo C. Fienga/LXX/IPF, 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 Gas-Giant Planet Saturn), 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 (---> Gases) present in the Upper Atmosphere of Saturn, 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 Saturn - as it is in this frame - would appear, to an average human eye, way lower than it has been shown (or, better yet: interpreted) here.

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