Question

Why is red the last color seen at sunset?

It reflects off the atmosphere.
It is scattered the least by the air.
It is bent the most by the air.
It is bent by raindrops.

Answer 1

Within the visible range of light, red light waves are scattered the least by atmospheric gas molecules. So at sunrise and sunset, when the sunlight travels a long path through the atmosphere to reach our eyes, the blue light has been mostly removed, leaving mostly red and yellow light remaining.