The blue color of the sky is due to the scattering of light, a phenomenon known as Rayleigh scattering. The scattering is caused by the atmospheric molecules, primarily nitrogen (\(N_2\)) and oxygen (\(O_2\)). These molecules scatter shorter wavelengths of light (blue and violet) more than longer wavelengths (red and yellow).
Thus, the blue color of the sky is due to the scattering of light by \(N_2\) and \(O_2\).