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Mars on 7th May at the 254mm: yellowish disk

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#1 stanislas-jean

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Posted 09 May 2014 - 10:01 AM

I had a look on Mars before yesterday evening with a window of 2 hours using the 254mm cassegrain.
In first, looking at Mars with naked eyes, it appeared also yellowish and not the orange-red usual color. This confirms the report of the 3rd.

I used the 254mm cassegrain for the report performed at 238x, more was not possible (the 312x too blurring with the seeing). The overall disk color was not usual and I confirm my observations of the 3rd with some adds, considering the observation in IL.
Generally, for all channel color observed, especially the red, the contrast levels are poor. Mare around Solis Lacus, Aonius, Sirenum were almost un-perceptible. Mare Boreum around the cap was not conspiscious. All the half tones features represented on the temperate area looked very low contrasted, Nikokeras and surroundings too, Elysium at the limb whitish with dark boundaries looked also low contrasted (seemed reinforced by the transition white dark boundaries, etc...
The best views were under the blue filter (relatively), and exceptionally poor in contrast under the red filter, the yellow at a lesser intensity.
Indeed the sketches seems to show hard contrasts, enhanced here for showing the difference between colors.

I remembered the vision of Syrtis Major during the great dust storm 2005 where it disappeared almost. I saw it in spite of in the 100mm refractor when its contrast was around 3% only. This was near a limit. Here on the 7th May, yesterday, we can attribute a level contrast of the features staying on the temperates zones to be say 5% more or less.
I we try to attribute a density of atmosphere attenuation, this could be minimum 50% (those features under clear atmosphere turn around 10% level). The tendency, stronger in red color surely.
Therefore in addition to the white hazze we see due to season occurences, there is an amount of dust with a non-negligeable density.
This is a fact.
Where is coming this dust:
- cap thawing speed very high, sothat dust are transported by the white hazze,
- deep white clouds at equator limbs crearing strong convections from the ground (we saw in yellow-red colors patches of bright ground area when white clouds disappeared).
Interresting to follow.
Yesterday, the 8th with the R100mm, the report helps to conclude to same tendencies.
Stanislas-Jean

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#2 niteskystargazer

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Posted 09 May 2014 - 11:01 AM

Stanislas,

Nice sketches of Mars, Yellowish Disk :).

CS,KLU,

:thanx:,

Tom

#3 Ed D

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Posted 09 May 2014 - 08:34 PM

Stanislas, excellent and well documented observation. I also made an observation with my 102mm achromat ( LINK ) with the same conclusions as both of your observations.

Not only is this interesting to follow, but I have been fascinated for the last eight months following the 2013-2014 apparition and how it has progressed.

Ed D

#4 stanislas-jean

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Posted 10 May 2014 - 05:28 AM

Thanks to all and ED.
I like the back ground disk color you drawed on your report.
This is realistic I found. The nake eye looking to Mars get the same coloring rather than the pink-orange usual. Lot of features reported.

I tried to make the follow-up about the color disk of the planet Mars yesterday and before.
I did reports last 8 and 9th using the good 100mm refractor with 200x magnification.
The overall color of the disk remains yellowish rather than the usual pink-orange color when the atmosphere is clear.
No enough time for checking in red color as clouding at home was very present.
On the 9th, the contrasts on the temperate zones and equatorial zones appeared clearer than past observations.
We will see later.
Indeed there was no dust storm occurence.
My reports are given below, unfortunately under grey scaling only.
Stanislas-Jean

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#5 Alpha Tauri

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Posted 10 May 2014 - 06:49 AM

Thanks for a well detailed illustration of Mars from you Stanislas -Jean. Interesting to note the progression of coloration throughout the viewing season.

Clear skies.

#6 CarlosEH

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Posted 10 May 2014 - 05:25 PM

Stanislas,

Thank you very much for your excellent observations and reports on Mars. It is interesting to have so much dust over the Martian atmosphere. It is possible that the North Polar Cap (NPC) dust storm reported approximately one week ago may have been the catalyst into generating more dust devils and eventually arriving at a global scale. It will be interesting to follow how long the dust may remain suspended in the Martian atmosphere. If using prior dust events as an example then the dust may be suspended for weeks to months. I look forward to your future observations.

Regards,
Carlos

#7 frank5817

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Posted 10 May 2014 - 06:36 PM

Stanislas,

Again some excellent sketching and reporting on the "yellow" planet.

Frank :)

#8 CarlosEH

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Posted 10 May 2014 - 10:42 PM

The North Polar Cap (NPC) dust storm may be seen adjacent to the NPC on Mars images obtained by my friend Christopher Go between the dates of April 30 and May 7 (see link blow). I believe that this is the progenitor storm among several more scattered over the planet.

I have attached a digital space painting that I produced a while back of a dust storm developing near the North Polar Cap (NPC). I hope that you like it.

Link;
http://jupiter.cstoneind.com

Regards,
Carlos

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#9 Uwe Pilz

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Posted 10 May 2014 - 11:33 PM

It is very interesting that you saw the chanes with unaided eye, as a different color!

#10 stanislas-jean

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Posted 11 May 2014 - 05:29 AM

Thanks a lot gents for your posts.
Carlos, well OK for the report concerning the dust storm catched by C. Go near the polar cap.
I followed Mars almost narrowly since 27-28 April, 3rd May and 7-8-9_10th May. The 3rd May report showed deep yellowish disk with faded contrast of features. At the 27-28th April, feature contrasts were conspiscious for main ones on a similar portion of Mars.
However, it should be interresting to remind some facts about the reflectivity noted on some "white" clouds catched at limbs, especially on the Syrtis Major occulted by.
S.M. was occulted by white hazze and and dust aswell, therefore by mist. S.M. was not visible by these dense hazze in all colors when just escaping the limb.
At the opposite limb the situation was on a similar figure.
On 27-28 April, presence of mist rather than white-blue clouds at limbs. Dust was at a density not negligeable already, but the overall disk color was not what we saw on the 3rd May.
So dust storm on the 30th April near the cap, well ok, but this is adding on the density in atmosphere for the least.
We should have a threeshold of dust density to reach in already white hazzy atmosphere for changing the discoloring of the disk. There should have also a saturation phenomena for creating this dense mist.
Yesterday the 10th May at the 100mm refractor, it appear to me that the discoloration is fading and the contrasts levels of features on the temperate zones are enhanced.
May be the beginning of the atmosphere clearing.
Ididn't have the time and the opportunity to push the violet filter.
We will see the development of this event later as it will become.
Thanks again for your interest of Mars events, discussing about is interresting to do.
Stanislas-Jean

#11 stanislas-jean

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Posted 12 May 2014 - 01:15 PM


I took some times for making a status of the surface discoloration disk observed recently.
The comparative sketches are colored in order to show the color evolution on the period from 28th April to 10th May.
Maria are not brownish or greenish as the exit pupill of the scope is turning on the range 0.5-0.8mm sothat features was appearing with grey tones. Their contrast levels are amplified to see the decrease amount, on the period 3rd-8th May they were fainter than normal.
On 10th I saw that the surface disk was on turning back to more pink-orange color as usual.
The color of Mars seen with naked eyes followed this evolution.
Sketches are more clearer than long explanations.
Stanislas-Jean

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#12 CarlosEH

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Posted 12 May 2014 - 02:28 PM

Stanislas,

Your excellent color observations of Mars do help to understand the change in hue over the planet over the past two weeks. It is interesting to note the strong yellowish color over the planet on May 3 and the more normal orange-pink color on May 10. Thank you for sharing them with us all.

Regards,
Carlos

#13 stanislas-jean

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Posted 13 May 2014 - 12:37 AM

Weather seems to be clearer a little later again here.
Will check again for the follow-up.
Stanislas-Jean.

#14 stanislas-jean

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Posted 14 May 2014 - 08:06 AM

Here are some read about this question of the atmosphere density charged of dust.
To whom interrested by the reasons explaining the discoloration of the planet.
Coupling Mars dust and water cycle :
http://www-mars.lmd...._oxford2014.pdf
high altitude dust in martian atmosphere:
http://www-mars.lmd...._oxford2014.pdf
Conferences hold begin of 2014 at Oxford :
http://www-mars.lmd....014/program.htm

I had a look on the Mars disk yesterday, still the discoloration.
Stanislas-Jean






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