Astronomy Picture of the Day
March 8, 2014

Craterland at Nightfall
Craterland at Nightfall

Credits: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington and Dr Paolo C. Fienga/LXTT/IPF for the additional process. and color.

The Sun was barely above the Local Mercurian Horizon when this image was obtained (by the NASA - MESSENGER Spacecraft at the beginning of January of the AD 2012), and the dark, long and strong Shadows visible everywhere do emphasize the ruggedness of the pictured Terrain. As a matter of fact, the Surface appears to be almost completely covered by - or saturated with - relatively small Impact Craters (according to NASA, about 2 to 3 km in diameter but, perhaps, we believe, as IPF, even much less than that). Furthermore, the peculiar (---> highly irregular) shape which characterizes so many of them, could reasonalbly suggest us that they are Secondary Impact Craters derived from a sizeable Impact which occurred in the vicinities of this area (approx. 88 Km - such as about 54,64 miles - wide) , but it is really difficult (let's just say: impossible, from here) to tell from which Larger Crater/s these small ones originated. Another possibility that we believe - as IPF - should be considered in order to explain such a peculiar configuration (---> appearance) of the visible Surface, is that this whole area was subject of an extremely heavy "rain" of Cosmic Debris, which might have originated from the fragmentation of a relatively large - but fragile - Celestial Object which did not successufully pass Mercury's Roche Limit.

Date acquired: January, 5th, 2012
Image Mission Elapsed Time (MET): 234240885
Image ID: 1226465
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
Center Latitude: 77,70° North
Center Longitude: 214,90° East
Solar Incidence Angle: 88,4° (meaning that the Sun, at the time that the picture was taken, was about 1,6° above the imaged Local Mercurian Horizon)
Emission Angle: 39,7°
Sun-Mercury-Messenger (or "Phase") Angle: 128,1°

This picture (which is an Original NASA - MESSENGER Spacecraft's b/w and Map-Projected image published on the NASA - Planetary Photojournal with the ID n. PIA 18060) has been additionally processed, contrast enhanced, Gamma corrected, magnified to aid the visibility of the details and then 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.

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