Why does the setting sun look reddish orange?

Question

i need proper scientific answer.

Answer 1

The Sun is like a dye-job blonde

http://en.wikipedia.org/wiki/Sun

The Sun has a spectral class of G2V. G2 implies that it has a surface temperature of approximately 5,780 K (or approximately 5,515 degrees Celsius / 9,940 Fahrenheit), giving it a white color which, because of atmospheric scattering, appears yellow as seen from the surface of the Earth. This is a subtractive effect, as the preferential scattering of blue photons (causing the sky color) removes enough blue light to leave a residual reddishness that is perceived as yellow. (When low enough in the sky, the Sun appears orange or red, due to this scattering.)

Answer 2

Dust, dirt, and now, pollution in the air between you and the sun. That's as scientific as I can get....sorry.