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Today's APOD features a stunning view (actually, it is just a portion of an Image-Mosaic made out of three pictures taken by the NASA - MESSENGER Spacecraft on April, 26, 2014) of the Complex Impact Crater known as Sander (so named after the German Photographer August Sander - who was born in Herdorf - Germany - on November, 17, 1876 and died in Cologne, on April, 20, 1964), which is located within the huge Mercurian Region known as Caloris Basin. The Floor of Sander Crater (approx. 51 Km - such as about 31,671 miles - in diameter) is covered (just like very many Mercurian Impact Craters) with a true Field of extremely bright Hollows. However, the reason why some Mercurian Impact Craters (even very close, like Sander and Munch Crater) show bright Hollows almost everywhere on their Floors and Slopes - Rims included -, while others do not, is still a fascinating Geological mistery. Date acquired: April, 26th, 2013 This picture (which is a crop taken from an Original NASA - MESSENGER Spacecraft's false-colors and Map-Projected image-mosaic published on the NASA - Planetary Photojournal with the ID n. PIA 18448) has been additionally processed, contrast enhanced, Gamma corrected, magnified to aid the visibility of the details and then re-colorized in Absolute Natural Colors (such as the colors that a human eye would actually perceive if someone were onboard the NASA - MESSENGER Spacecraft and then looked outside, towards the Surface of Mercury), 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 Mercury, each having a different Albedo (---> Reflectivity) and Chemical Composition. |