The first word we need to know is "Scattering". It is a phenomenon of certain wave passing through an obstacle and proceeding in several different ways. It is known as the shorter the wave, the wider it scatters.

In a visible rays, blue scatters better while the red doesn't since its wave length is longer than that of the blue's

One more thing we need to know, we only see the light that comes directly through our eyes. We'll never be able to see the sunlight passing through the atmosphere in different ways from our eyes. Now this theory also applies to the fact that we are only capable of seeing the light of the laser pointer when it's pointing directly at us. (the reason why we can see it's path even though it's pointing somewhere else is because the light of the laser pointer is "Scattered" by dirts or smokes in the air)

Back to the main point, we cannot see the sunlight passing through the atmosphere and going outside of the earth. If scattering effect doesn't exist, the color of daylight would be black. However, parts of the lights that bounced back out of the earth(especially blue) would scatter back towards our eyes again caused by their shortest wave lengths taking effect. That is why the sky looks blue.

During the sunrise or sunset, the altitude of the sun is relatively very low. To emphasize more on this, the sunlight passes very long way through the atmosphere. Through this process, blue gets scattered away unlike during the day and reds remain a lot during the sunset. Therefore, the sun would look more red resulting the sky change its clothes in red also. Of course the color of the sky very far away from us would still be blue.

view from the sky during the sunset. above it is still blue.



words & photos by CHA