Why Does The Sky Go Red At Sunset?

At sunset (or sunrise) the sun is very low in the sky.  This means, effectively, that the light from the sun has to travel through more of the earth's atmosphere to reach our eyes.  


The sun emits light in the main colours of red, green, blue, ultraviolet. Red has the longest wavelength, which is bigger than most of the molecules in the atmosphere.  As a result, red light passes straight through air molecules, it doesn't get reflected somewhere else (or 'scattered').   So red light travels in a straight line to our eyes.

Blue and green light have shorter wave-lengths, so they get scattered more easily.  The more atmosphere they pass through, the more scattering happens.  When the sun is low in the sky the blue and green light simply can't travel straight to our eyes because they get scattered away.  This leaves the red light to come straight through, and thus the sun itself often appears especially red at sunset.  Remember that red light travels in a straight line to our eyes, but away from the sun the light gets more grey as more of the scattered blue, green and UV light reaches our eyes from these areas.

No need detail, we can say due to sun color is like fire, so it makes the sky is red when sun is down or rise.

Because they getting the air inside of it and energy if you dont believe it then that fine but that secret of earth ! Ask god than i can read god and see him in my life!