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David Williams
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 Posted: Sat Jun 21, 2008 8:23 am Post subject: Green Areas on Mars |
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-> I am still wondering why telescopic photos of Mars from Earth show green
-> areas that expand and contract with passage of the martian seasons,
They do?
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Ralph
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| Posted: Sat Jun 21, 2008 11:00 am Post subject: Re: Green Areas on Mars |
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Not knowing which pictures you mean, I can only guess.
Chances are, the pic was 'false-colour', showing something that changes with
time...
maybe temperature?
"David Williams" <david.williams@bayman.org> wrote in message
news:1214018636.873.1214010129@bayman.org...
| Quote: |
-> I am still wondering why telescopic photos of Mars from Earth show green
-> areas that expand and contract with passage of the martian seasons,
They do?
dow |
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Raymond C. Glassford
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| Posted: Sat Jun 21, 2008 11:26 pm Post subject: Re: Green Areas on Mars |
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Ralph wrote:
| Quote: |
Not knowing which pictures you mean, I can only guess.
Chances are, the pic was 'false-colour', showing something that changes
with time ... maybe temperature?
"David Williams" <david.williams@bayman.org> wrote in message
news:1214018636.873.1214010129@bayman.org...
-> I am still wondering why telescopic photos of Mars from Earth show
-> green
-> areas that expand and contract with passage of the martian seasons,
They do?
dow
|
Forgive my age-induced ignorance of this topic. My thinking on
scientific studies of Mars was unduly influenced by earth-based
telescopic observations of the planet conducted during the early to
mid-twentieth century. Reading "Mars and Its Canals", by Percival Lowell
(1907), during my teen-aged years certainly was not a contribution to
"good" scientific knowledge, although the book was a good read.
After doing some more Googling, and summing everything up, I have
concluded that there truly are no vast "green areas" on Mars. The "green
areas" visually seen by some observers seem to have been tricks played
on their eyes, due to the contrasting colors of the reddish-ocher areas
and gray areas of basaltic rock. The "green areas" photographed using
earth-based telescopes shortly after the invention of color photographic
films were probably "green" only because the color dyes used in the
films did not accurately reproduce actual colors. It is notable that
Hubble Space Telescope images of Mars now show the "green areas" as gray
in color (Syrtis Major, etc.), although, if my memory serves me
correctly, the earliest published Mars images from the Hubble Space
Telescope showed those gray areas as being bluish-green; obviously, some
color-correction work has been done over time to make image data more
closely reflect reality. It should be noted that building true-color
images from raw image data is a time-consuming and exacting process.
The myth of the "green areas" is still alive and well, however, as I
discovered from my Google search. At least one individual is promoting
the idea that tree-like vegetation exists on Mars. See:
http://www.ufoarea.com/aas_mars_esa_greentrees_nb.html
In this case, I noticed that the original ESA Mars Express images show
charcoal-gray to black areas whereas the "trees-on-Mars" proponent's
images show those areas as green in color. My guess is that some
creative color-fill work was done on the original images. Do not believe
everything you see.
Consider, also, the fact that color images taken by spacecraft are
sometimes released for publication before they have been precisely
color-corrected. See:
http://www.badastronomy.com/bad/misc/hoagland/green_mars.html
which shows "green areas" on Mars where they should not be, due to
premature release of non-corrected images taken by ESA Mars Express.
So, in summation, I was not trying to mislead anyone in my original
post; I was merely trying to catch-up and bring my knowledge up-to-date
on this particular topic. Still yet "officially" unexplained, however,
at least to my mind, is why telescopic observers seemed to see the
"green areas" recede and expand with the martian seasons. Unfortunately,
I must conclude that, then as now, even scientific minds preferred to
believe what they wanted to believe. At present, I can only guess that
what they presumed to be vegetation proliferating in the warmth of the
martian Spring and Summer was actually gray basaltic rock being cleared
of overlying reddish-ocher dust by increasingly violent winds. As is
true here on Earth, warming temperatures spawn violent weather patterns. |
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