The debate has raged since the 1970s when Nasa's Viking 1 lander became the first spacecraft to touch down on the red planet/ Its initial images revealed what appeared to be a blue sky (right), but in reality Nasa says the planet has a red/orange sky. On the left is a processed image of what Nasa believes Mars to look like
As I said...it's been an issue for some time.
Image on right (with the blue sky) was on monitors color calibrated minutes earlier. Image on left is the consensus view of what the color SHOULD be.