Astronomy Picture of the Day
April 9, 2015

'Ghost' Crater on Mercury
'Ghost' Crater on Mercury

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.

This relatively small (only about 8 Km - such as approx. 4,968 miles - in diameter) "Ghost" (----> almost invisible) and extremely old (see the huge amount of tiny Impact Craters superposed on the Floor of the bigger one) Unnamed Impact Crater, lies in Mercury's Northern Volcanic Plains.

As a matter of fact, at some point after its formation, huge amounts of Lava (coming from a still undefined source) completely filled the Crater itself, and only a hint (---> a very little bit) of a Rim has been left behind, as the proof that this Impact Crater really exists. Just out of curiosity, no "Hollows" - and this circumstance is truly unusual for a Mercurian Impact Crater - are visible anywhere on the scene.

Date acquired: January, 23rd, 2015
Image Mission Elapsed Time (MET): 64352274
Image ID: 7849552
InstrumentNarrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Center Latitude: 16,85° North
Center Longitude: 79,73° East
Solar Incidence Angle (at center frame): 79,6° (meaning that the Sun, at the time that the pictures were taken, was about 10,4° above the imaged Local Mercurian Horizon)
Emission Angle (at center frame): 0,1° (meaning that the Spacecraft was almost perferctly perpendicular as to the imaged Surface at the time when the picture was taken)
Sun-Mercury-Messenger (or "Phase") Angle (at center frame): 79,7°

This picture (which is crop taken from an Original NASA - MESSENGER Spacecraft's b/w and Map-Projected image published on the NASA - Planetary Photojournal with the ID n. PIA 19272) 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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