Astronomy Picture of the Day
July 18, 2013


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 Region visible in this image-mosaic made by three frames taken by the NASA - MESSENGER Spacecraft on February, 3, 2013, is located in the Mercurian Northern Mid-Latitudes and it shows us a small (a VERY small!) section of the gigantic and extremely long Rays that emanate from the very well known Impact Crater Hokusai, along with the tiny (but very Bright) Rays of a much smaller Impact Crater (approx. 12,3 Km - such as about 7,63 miles - in diameter) that is positioned in the South/Eastern quadrant of the image (at about 4 o'clock).

The Rays which often surround Impact Craters are produced when a certain quantity of Rocky Material is excavated - at the time of the Crater's formation - and then "thrown" away, all across the Surface of the Celestial Body on which the Impact Event has occurred. In this case, the "butterfly-like" pattern of the smaller Rayed Crater is believed to be a consequence of a very low-angle impact: a situation, this one, where the excavated Rocky Material is (according to our simulations) ejected along asymmetrical patterns.

Date acquired: February, 3rd, 2013
Images Mission Elapsed Time (MET): 2001682, 2001674, 2001678
Images ID: 3436082, 3436080, 3436081
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
Center Latitude: 47,96° North
Center Longitude: 7,84° East
Solar Incidence Angle: 48,0° (meaning that the Sun, at the time that the picture was taken, was about 42,0° above the imaged Local Mercurian Horizon)
Emission Angle: 0,1°
Sun-Mercury-Messenger (or "Phase") Angle: 47,9°

This picture (which is a crop taken from an Original NASA - MESSENGER Spacecraft's false colors Map-Projected image-mosaic published on the NASA - Planetary Photojournal with the ID n. PIA 17381) has been additionally processed, contrast enhanced, magnified and then re-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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