why is the sky blue A clear cloudless day-time sky is blue because molecules in the air scatter blue light from the sun more than they scatter red light. When we look towards the sun at sunset, we see red and orange colours because the blue light has been scattered out and away from the line of sight.

I found this from a website. Here is the link  math.ucr.edu/home/baez/physics/General/BlueSky/blue_sky.html