Why is the sky blue? What makes the sunset red?

The sun produces color spectrum that blends into white lights. The colors are red, orange, yellow, green, blue, indigo and violet : a rainbow. These are the correspondent of different frequencies and wavelength of light energy. The seven colours of the spectrum all have different wavelengths and they are arranged accordingly. Violet, indigo and blue light have a higher frequency - which means shorter wavelength - than red, orange, and yellow light.

When the white light from the sun shines through the Earth's atmosphere, it collides with gas molecules. Those molecules scatter the light. Blue light has a high frequency, and it is scattered ten times more than red light.

But, the red light that you see from sunset is not scattered continues on in its original direction. When the sun is on the horizon (the sunset position), its light takes a longer path through the atmosphere to your eyes than when the sun is directly overhead. By the time the light of the setting sun reaches your eyes, most of the blue light has been scattered out. The light you finally see is reddish orange, the colour of white light minus blue.

The dust and pollution molecules are also having role in this. Those molecules also scatter the light and make sunset more brilliant.

Labels: colors, energy, light, physics, sky, sunset, wave