Fact or Fiction: Is Mars' sky really blue, and is NASA doctoring photos?

Did you ever wonder about the red tinted images from Mars?

No? Maybe that's because you haven't seen any other colorization in the main-stream media like Newspapers and TV.

What is the reason for the red picture and especially for the red sky on them?
If you ask a Meteorologist about the reason for blue sky on Earth, he will name the Rayleigh scattering.
If you ask a NASA Scientist about the reason for red sky on Mars, he will name the fine dust in the Atmosphere which scatters light like during sunset on Earth.

But there are not alway dust-storms on Mars which pollutes the Atmosphere.
So there have to be also days which show blue sky!
Even NASA / JPL writes in this article about the possibility of blue sky and 3 days before Pathfinder landed, this note appeared in a press release by NASA:

"If dust diffuses to the landing site, the sky could turn out to be pink like that seen by Viking," says Philip James of the University of Toledo. "Otherwise, Pathfinder will likely show blue sky with bright clouds."

And the pictures of this clear blue sky do exist! Especially from the Viking Mission, as you can see on the next pages. (read more)