Why sun appers big in size at sunset and sunrise?
The sun appears red because the atmosphere scatters blue light more efficiently. Since the sunlight has to travel through significantly more atmosphere when it is on the horizon (due to the angles involved), much more of the blue (and green and purple) light gets scattered and redirected in a random direction that is not toward you. But the red light gets scattered less, so the red light makes it from the sun to your eye. Since there is more red light, the sun looks red. This is actually the same reason why the sky looks blue when the sun is over head. The blue light that was sent from the sun and would have hit somewhere other than where you are standing gets scattered by the atmosphere and redirected in a random direction, that may be toward you. The red light travels striaght through the atmosphere and hits where it was sent, and does not get scattered towards you. So the blue you see in the sky is blue light that the sun sent toward some other location, but the atmosphere redirecte
