Astronomy Picture of the Day
May 4, 2014

Craters and Craters
Craters and Craters

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.

Running diagonally though the scene (which is approx. 14 Km - such as about 8,69 miles - across), and running from the upper left (Sx) to the lower right (Dx) corner of the frame, you can see the Wall of an ancient Impact Ccrater that encompasses another Impact Crater known as Purcell. Purcell Crater and this other one (both quite large) are both pretty ancient, as evidenced by the numerous small Impact Craters that cover them, including their Walls. Furthermore, this High-Resolution Image taken by the NASA - MESSENGER Spacecraft on April, 11, 2014, also reveals how the small Impact Craters that formed on the Wall display some differences from the ones which formed on the Flat neighboring Surfaces. Frankly speaking, we, as IPF, honestly believe that the differences (mostly in shape) existing among these smaller Impact Craters that NASA is talknig about, may simply (and reasonalbly) be due to different Angles of Impact, rather than their age and/or the size of the Impactors that created them.

Date acquired: April, 11th, 2014
Image Mission Elapsed Time (MET): 39535979
Image ID: 6104625
InstrumentNarrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Center Latitude: 81,25° North
Center Longitude: 212,20° East
Solar Incidence Angle: 81,4° (meaning that the Sun, at the time that the picture was taken, was about 8,6° above the imaged Local Mercurian Horizon)
Emission Angle: 36,3°
Sun-Mercury-Messenger (or "Phase") Angle: 82,5°

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 18246) 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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