# Why does light at sunset appear red?

The sun light has almost all wavelengths of Electromagnetic spectrum from shortest wavelength X-rays to longest wavelength radio waves. But we can see only visible spectrum ranging from $4000 \setminus \setminus \textrm{\to} \setminus 8000 {A}^{\setminus} \circ$.
According to Rayleigh's elastic scattering, the degree scattering is inversely proportional to $4$th power of wavelength. In this way, the longest visible wavelength i.e. red light scatters less.