The Martian air?

[Artlav]

I've been lately interested in the way the atmosphere of Mars looks like, and the thing seems somewhat weird.

How dense is it?
Or, better, what defines light absorption in the air?


The biggest one was about this image:

Full: http://www.awalkonmars.com/A1318-325PCM12E1v1anno.jpg (43Mb)
Take a closer look at the horizon - the distant hills are quite shaded by the air, yet they can't be too far away, probably closer than the same level of shade on Earth.


Another one of a kind:

Full: http://upload.wikimedia.org/wikipedia/commons/2/20/Victoria_Crater,_Cape_Verde-Mars.jpg (3 Mb)
Again, horizon - the distant hills are just as sharp as the foreground in terms of color.
And, we see an entirely different, yet still-bright color of the air.


Now, a different time:

Again, the distant objects are well shaded and the air feels very dense, yet the coloration is incomparably less colorful than on Earth.


And an overhead sun picture from yet another place :

Where we see yet another sky color and clean-feeling air.


My best guess is dust to account for all that, but does it account?
What defines the way air looks on this kind of a planet?


One more interesting view:

The clouds seen from the ground.
If the air is dense enough to support clouds, what are they made of?

Looking up again, we see that there are enough air to make a halo around Phobos (Is it? Or is it a camera effect?) as well as to support some traces of clouds.


Now, for a different view:

A weird-looking something in the air. Is it clouds?
What are they made from?
Notice the thickness of the air.

Here we see the thick evening-air edges on the disk.
Without any traces of the kind of clouds in above picture.

Here what look like a dense air shell visible on the edges.

Yet, a higher-away view gives a Moon-like horizon color-lessnes.

Some other images show a rather blurry surface, relative to foreground objects sharpness.


Now, the rest of the questions are:
1. What colors are the sky on Mars?
Why there are no 2 similar-colored pictures of it?
What defines them besides different cameras and exposures?

2. Does anyone know where to get some high-quality pictures of Mars - 90* UPWARDS panorama and low-orbit views?

3. Does anyone know where to get an image of Martian clouds form orbit, if they are visible?

4. And, just how much air is needed to make stars invisible at noon (for a sun shaded camera) on a planet as far from the sun as Mars?

 

[T.Neo]

Where we see yet another sky color and clean-feeling air.

I think that sky colour is because NASA believed the sky to be blue, and played around with their camera filters to make it look that way, in effect, messing up the reality to fit the theory when the instruments were working correctly. :lol:

 

[Hielor]

It's a conspiracy. Your photos clearly show that Mars has a thick, breathable atmosphere.

I wonder why they're covering it up.

 

[neGcon]

Wikipedia has pretty good info about it:
http://en.wikipedia.org/wiki/Atmosphere_of_Mars

About the Pictures:
I think some of them are taken not using the human eye visible spectrum - and then somehow coloured afterwards

I wonder if the current mars rovers have a "gray card" onboard to calibrate the white balance - or how do they measure white balance?
Because the typical consumer digital camara has real trouble get this right at odd illumination - not to think about mars

 

[DaveS]

I wonder if the current mars rovers have a "gray card" onboard to calibrate the white balance - or how do they measure white balance?

They have a color calibration target which doubles as a sun dial. So they have preflight calibration photos of the color calibration target which they use as a reference.

 

[Coolhand]

yeah all those photos have been taken on different equipment thats calibrated differently and have been processed differently so they'll all have different tones, making it very difficult to find the correct colours... i think some guesswork is in order.

 

[TSPenguin]

Or, one could be so blunt to ask the friendly folks of the governmental agencies, or other experts on the field.
Beats guessing IMO.

 

[-Pv-]

Some Mars images are color corrected and some are not. If you search for color corrected Mars pics you will see more consistency (depending on the spacecraft, altitude, Sol, exposure time, focus, data rate and a host of other variables.) Some "blury" images are caused by Mars global dust storms. Some photos are not planned but lucky captures of random fields of view.
-Pv-

 

[Nerull]

4. And, just how much air is needed to make stars invisible at noon (for a sun shaded camera) on a planet as far from the sun as Mars?

With the right optics, bright stars can be seen on Earth in broad daylight.

 

[Coolhand]

Or, one could be so blunt to ask the friendly folks of the governmental agencies, or other experts on the field.
Beats guessing IMO.

sure, ask 3 different agencies and get 3 different answers. What colour is the sky on earth? every time i go outside it looks slightly different, depending on location, season, time of day, atmospheric dust, moisture, etc.

 

[TSPenguin]

That is true... But getting real data instead of matching pictures with unknown processing should yield more accurate results.

 

[markp]

That's a very nice collection of Mars atmosphere pictures!

Dust effects the optical properties of the atmosphere. Also the density of the atmosphere can vary a lot.

 

[Suzy]

The Sky on Alien Worlds is an interesting read (only briefly mentions Mars though). Don Davis also has a page on Mars colors.

 

[Belisarius]

From the book "Mapping Mars" by Oliver Morton (p93-94):

"The Vikings had colour cameras...there were reference charts attached to the landers... Unfortunately those charts were not visible in the first images from Viking I, and so the colour balance had to be done by guesswork. The result was a brownish-red surface with a greyish sky that in some prints came out blue... A couple of days later pictures of the colour chart on Viking 1 were obtained and James Pollack... recalibrated the camera. Now the soil and rocks were red and the sky dusty pink...
Using the lighting and colour definitions set down by the... Inter-Society Colour Council, the Viking lander team gave its final verdict: the soil... was a 'moderate yellowish brown' and the sky 'light to moderate yellowish brown'."

Hope you find it informative