Mercury? Comets have done strangely dark black color of the planet could be due to impacts with micrometeorites of cometary origin rich in carbon. The hypothesis, published in Nature Geoscience, Mercury would explain why, despite the lower abundance of iron, is not reflective of the Moon Marco Malaspina Monday, March 30, 2015 @ 18:17 agglutinated similar to the material found on the surface of Mercury, reproduced in the laboratory by an impact at high speed. Credit: Megan Bruck Syal Even Mercury uses a matting. Not that I have oily skin, mind you. But close to the Sun as it is, if you do not adopt any measure, you know that shiny? But look at him: his beautiful face dry reflected even less than that of the Moon. What's her secret? It's been a while 'that astronomers if they ask. To be precise, since the NASA's MESSENGER spacecraft, which orbits from 2011, analyzing the spectrum of light reflected from the surface of the planet has confirmed the absence of the absorption line at 1 micron: that characteristic of silicates that contain iron , present in the infrared radiation reflected from the Moon and asteroids. If there is that line, the researchers say, means that on Mercury's surface oxide ore - present in the layer of black powder that breaks down, in fact, the reflectance of the Moon - does not exceed 2-3 percent. Too little to justify the opacity.So what? A "mattifying foundation" alternative to the face of Mercury could be the comet dust. Or rather, carbon dust - mostly in the form of graphite or amorphous, but scientists do not rule out that at least a fraction is made up of nanodiamonds - brought by micrometeorites of cometary origin. This hypothesis explored and described in the latest issue of Nature Geoscience by a team led by Megan Bruck Syal, a researcher at the Lawrence Livermore National Laboratory (LLNL) in California. According to their calculations, the soil of Mercury contains, per unit area, an amount of carbon rich material about 50 times higher than that present on the lunar surface. This is because the impacts with comets, carbon-rich and present in quantities inversely proportional to the distance from the Sun - then with a frequency of collisions much higher on Mercury than on the Moon. And even more so as a result of impacts with micrometeorites, originated at a time in prevalence from comets, as shown by the analysis carried out on samples collected on Earth, especially in Antarctica. The hypothesis was tested with a series of laboratory experiments in which, using dell'Ames Vertical Gun Range at NASA, Syal and colleagues reproduced in hypervelocity impacts with micrometeorites, getting a surface staining collision similar to that of the face of Mercury.
http://www.media.inaf.it/2015/03/30/mercurio-carbonio-comete/This look interesting
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