The Martian Sky |
The Martian Sky |
Oct 11 2009, 06:41 PM
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IMG to PNG GOD Group: Moderator Posts: 2254 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
I have been attempting to make computer generated images of the Martian atmosphere, both as seen from the surface and from space. To check the results I have been looking for spacecraft images to use as ground truth. I have found lots of images - by far the best ones I have found are from UMSF in this thread: http://www.unmannedspaceflight.com/index.php?showtopic=3324
However, I'm always looking for more ;-). So if anyone knows of more and/or better images I'm interested in them. What would be best are mosaics showing the sky from the horizon (with the horizon/surface visible) and towards the zenith. The sky varies a lot because of variable amount of dust but the general impression I get is that the sky is bright near the horizon (usually brighter than the surface) but gets much darker higher in the sky. There is probably a fairly large, bright area in the sky near the sun, possibly less reddish (lower R/B ratio) than parts of the sky farther from the sun. I'm already getting fairly interesting results, this one has a field of view of 90 degrees: (needless to say this one is 'overexposed' near the horizon; dynamic range is sometimes a problem) The problem is that even though this may not be bad the limb currently appears far too bright as seen from space : This shows that my atmospheric model is erroneous in some way - I suspect that as seen from the surface the Martian sky is darker high above the horizon than I have been assuming. |
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May 12 2015, 06:59 PM
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Senior Member Group: Members Posts: 1669 Joined: 5-March 05 From: Boulder, CO Member No.: 184 |
Here is a more direct link to the recent paper that explores the question of why the sunset on Mars is blue:
https://www.osapublishing.org/ao/fulltext.c...8&id=281919 This comes to mind as the recent APOD with Damia's Mars sunset mentions the reasons for the blue sunset aren't completely understood. This paper though seems to explain things pretty well, in that the blue sun is from a negative Angstrom coefficient (associated with a specific dust size near the wavelength of light), and the blue surrounding the sun is related to the Mie scattering with the dust where the blue Airy diffraction disk is more concentrated than the red one. The composition of the dust is only important (and producing red) at greater scattering angles in other parts of the sky. These colors are there to some extent at other times of the day as well. -------------------- Steve [ my home page and planetary maps page ]
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