Astronomy Picture of the Day
August 23, 2014

Back to Europa
Back to Europa

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

This image-mosaic of the Jovian moon Europa (colorized in Absolute Natural Colors) is a product of Clear-Filter Grayscale Data obtained from one orbit of the NASA - Galileo Spacecraft, combined (---> merged) with Lower-Resolution Color Data taken on a different orbit. The bluish-white Terrains indicate the presence of (always relatively speaking) pure Water Ice, whereas the reddish areas contain Water Ice mixed with Hydrated Salts, possibly (but there is no way, as of now, to be sure) Magnesium Sulfate or even Sulfuric Acid. The reddish Material is associated with the broad Flow-like Band that is clearly visible in the center of the image, as well as with some of the narrower Flow-like Bands, Ridges, and disrupted Chaos-type Surface Features which are present almost all over the Surface of Europa. It is possible, but yet to be proven, that these Surface Features may have communicated (or may still communicate!) with a Global Subsurface Ocean Layer during - or even after (and maybe now) - their formation.

The imaged area measures approximately 101 by 103 miles (such as about 162,54 by 165,76 Km). The Clear-Filter Grayscale Images were obtained on November 6, 1997, during the NASA - Galileo Spacecraft's 11th orbit around Jupiter, when Galileo was approximately 13.237 miles (such as about 21.302,8 Km) from the Surface of Europa. Afterwards, these aforementioned images were combined with Lower-Resolution Color Data obtained in the AD 1998, during the 14th orbit of Jupiter, when the Spacecraft was approx. 89.000 miles (such as about 143.231,26 Km) from the Surface of Europa.

This frame (which is an Original NASA - Galileo Spacecraft's false colors and NON Map-Projected image-mosaic published on the NASA - Planetary Photojournal with the ID n. PIA 18413) has been additionally processed, contrast enhanced, magnified to aid the visibility of the details, 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 - Galileo Spacecraft and then looked outside, towards the Jovian moon "Europa"), 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 Europa, 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 Europa - 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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