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This image, acquired by NASA’s MESSENGER spacecraft on December 12, 2011, reveals the blue coloration of the 32-mile (52-km) -wide Degas crater located in Mercury’s Sobkou Planitia region.
Degas’ bright central peaks are highly reflective in this view, and may be surrounded by hollows — patches of sunken, eroded ground first identified by MESSENGER last year.
Such blue-colored material within craters has been increasingly identified as more of Mercury’s surface is revealed in detail by MESSENGER images. It is likely due to an as-yet-unspecified type of dark subsurface rock, revealed by impact events.
The slightly larger, more eroded crater that Degas abuts is named Brontë.
The image was acquired with MESSENGER’s Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS), using filters 9, 7, 6 (996, 748, 433 nanometers) in red, green, and blue, respectively.
Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington.
So the blue in this picture is actually sort of blue, but the red and green are certainly not representing those actual colors. I wonder what it would look like in true color? Perhaps just a darker shade of gray, if it is a broad visible absorption.
According to David Blewett, MESSENGER team scientist at JHUAPL, to the human eye “Mercury would appear to be greyish-brown in color (not much different than greyscale).” So although there ARE color variations, they are not as extreme to our vision as they seem in the MESSENGER wide-angle composites.
Could it be that the impactor contained the blue material? If not, why aren’t the surrounding craters blue? Any guess as to what the material is?
Since Degas is clearly the youngest crater of the bunch, and this is a region formed from volcanic activity (lava flows), it may be that the impact that formed Degas happened to throw out material from a different magma source than the others, if the magma was in motion. Or, the older craters may have had their blue colors eroded away since. Again, just thoughts.
Perhaps the material bleaches in the sun over time?
As far as we know, it could be something unknown to science. Collisions happen all the time. Hopefully they keep studying this, I am curious.
This picture is just amazing. It looks like the grey-blue crater is metallic like selenium or lead, and even looks more like cement dust. Reminds me of the old story about Mercury that dates back ages that says Mercury is so close to the sun, that lead would melt on its surface!
Also the dimples in the centre of these craters look a little odd and seem to have been subject to erosion.
I’m unsure, but I thought the bombardment phase in the formation of the solar system was far more severe than planets much further out. The bizarre nature of Mercury’s surface and composition is a reflection of that.
Just an idea. UT might like to chase up one of the astronomers who have been working on the project and get their unique “professional” view about their discoveries here. I’m sure they would love to advertise their work here.
Again, I do appreciate this story!