Colour skies?
I have been a BBC Sky at Night Magazine reader and watcher for many years and enjoy both greatly, but I have a question about the pictures used in articles on Mars. When talking about the atmosphere, why do you have a picture in black and white showing dark skies and white cloud, such as the image of Martian noctilucent clouds in Stuart Atkinson’s feature?
(See ‘The Red Planet’s Sky at Night’, Feb 2021 issue, page 66.) It is the same on the NASA site; why do they show black and white pictures of superb scenery with the sky in the top of the shot? Why build a rover costing billions of dollars only to take black and white pictures? Do NASA and your magazine want to hide the fact that the Martian skyline is blue like on Earth? When I look at NASA photos for the various rover missions the sky in many shots is blue. All I want is colour pictures of our neighbour to highlight its beauty; red or blue sky, I want to see it as it is. Jason Trussell, Essex
We’re Jason! million isn’t as certainly Mars bright, km from rovers and not Earth where are hiding operating where the anything, atmosphere sunlight 180 is nitrogen primarily and carbon oxygen dioxide on Earth) (rather and than contains more dust. If colour images look monochrome it’s due to these factors.
Martian sunsets do look blue close to the horizon, but the sky on Mars is generally a butterscotch colour because of all the dust.
Some rovers’ cameras are colour, some are black and white with filters, and some have both. Black and white cameras are better resolution than colour cameras, so if the mission team wants detail rather than colour, black and white images are better quality and quicker to obtain. – Ed.