Astronomy Picture of the Day
October 28, 2012

Hollows in De Graft Crater
Hollows in De Graft Crater

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 exquisite image, taken by the NASA - MESSENGER Spacecraft (and acquired as a High-Resolution Targeted Observation) shows the Impact Crater De Graft: a complex Mercurian Crater whose diamter is approx. 75 Km and that contains, as you can easily see for yourself, quite a few Hollows (such as bright, Shallow Depressions which may have been formed by the - most likely sudden - loss of some kind of Volatile Material that was trapped in the Subsurface) on its Floor and Central Peaks. It is not yet known exactly how these Hollows actually form, but the MESSENGER Team is actively working to understand this really unique phenomenon. As a matter of fact, pristine Hollows in (relatively) young Impact Craters like this one, may still be forming even at the present day. In our opinion, as IPF, the bright, whitish Material left on and around the Hollows could just be the Physical Evidence (and Remnant) of the verification of a phenomenon of Outgassing (such as, in other words, such a bright Material should be fresh - meaning just exposed on to the Mercurian Surface, and therefore to the Space Environment - Dust and Powdery Debris that, in a way, could resemble to Talc).

Date acquired: July, 16th, 2012
Image Mission Elapsed Time (MET): 250938380
Image ID: 2211371
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Center Latitude: 21,88° North
Center Longitude: 1,63° East
Resolution: 47 meters/pixel
Solar Incidence Angle: 74,7° (meaning that the Sun, at the time that the picture was taken, was about 15,3° above the imaged Local Mercurian Horizon)
Emission Angle: 40,8°
Sun-Mercury-Messenger (or "Phase") Angle: 115,6°

This picture (which is an Original NASA - MESSENGER Spacecraft b/w frame published on the NASA - Planetary Photojournal with the ID n. PIA 16432) has been additionally processed 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 down, 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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