Why Sunset is reddish ?

This is the question often asked by my friends or young relatives who have no science background. Many professional people would not be able to answer this too as they had returned their scientific knowledge to their high school teachers. Can you answer me?

To me, colours of light appear to be an illusion. It you look right angle into this photo, it is mainly reddish and yellowish orange. But if you look from bottom up, it is almost totally red. If you look from top down, the colour appears to be bluish. So, it must be something to do with our angle of sight.
In fact, light comprise a mixture of visible electromagnetic wavelengths to our eyes (to other animals, the perception may be different). These colours are red, orange, yellow, green, light blue, deep blue and violet. Our atmosphere contains a lot of molecules of gases and dusts. Light scatters as it passes through such particles. But blue light scatters the most as these particles are generally smaller than its wavelength (this is called Rayleigh Scattering). During the mid-day, the atmosphere above us is thinner directly towards the sun, we see yellow sun, while towards other area of the sky, the blue light is scattered, we see blue sky. At evening, our line of sight is at an angle to the horizontal, the atmosphere is thicker, when most of the blue light is scattered, leaving the red,orange and yellow colour waves approaching us from the sun.