Astronomy Picture of the Day
March 31, 2014

Double Crater
Double 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.

These two (always relatively speaking...) "fresh" Impact Craters - the bigger one being approx. (~) 34 Km (such as about 21,11 miles) and the smaller one being approx. (~) 20 Km (such as about 12,42 miles) across -, share an (highly degraded) Rim, and both contain (inside and, particularly, in the close proximities of their Shared Rim itself) something that is commonly known as "Slumped Material" (---> such as Fine Rocks and Dust which originated from Land and/or Dustslides).

The main questions that a picture like this one may suggest, as you can easily wonder, are the following ones: did these two Impact Craters form during the same Impact Event, from two different Impactors which hit the Mercurian Surface almost at the same time? Did the Rim of the larger, and highly degraded Impact Crater - located on the right (Dx) and lower side of the image - influence the structure of the "Shared Rim"?

According to NASA's Planetary Scientists, only Higher-Resolution Images of this area - images which shall hopefully be taken during the NASA - MESSENGER Spacecraft 's final year of operations (and even though we, as IPF, do believe that a final and definitive answer to those questions, most likely, will never come) - might help (a little bit) to elucidate their origin.

Date acquired: October, 12th, 2011
Image Mission Elapsed Time (MET): 226922649
Image ID: 876240
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
Center Latitude: 64,76° North
Center Longitude: 255,50° East
Solar Incidence Angle: 72,9° (meaning that the Sun, at the time that the picture was taken, was about 17,1° above the imaged Local Mercurian Horizon)
Emission Angle: 14,3°
Sun-Mercury-Messenger (or "Phase") Angle: 60,6°

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 18189) 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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