On
earth,the molecules that make up our cotmosphere black the sunlight. And they are much better at scattering blue
light than red light (their ability to scatter light falls off sharply as the wavelength of the light gets larger).So some blue light gets scattered out of the direct sunbeam and goes into the rest of the sky.
On mars, there is much less atmosphere. In fact,if it weren’t for the dust in Mars’s sky, the sky would be nearly black, that dust, blocks light of all colours almost equally, and there is enough dust to limit visibility to about 20 miles.Since the dust is coloured by iron oxides, it absorbs the blue light and scatters the red light,giving the sky a rusty
colour.
Sunsets on
Earth have a red,orange or golden colour.On mars, while the sky is red during the day, the sunset is blue. The reason fopr this is that the dust particles always make a blue halo around the sun on mars, but the halo is only easy to see when light passes through all the dust while coming our the horizon.