Fill a clear glass with water and shine a torch through it onto a thick piece of white cardboard. Now pour some milk into the water and try again.
The resulting light the second time is your own personal sunset. Just like real sunsets the tiny particles in the milk behave like dust particles in our atmosphere and scatter the individual colours in a light spectrum. The blues and purples scatter the most leaving the reds and oranges to dominate. When the sun is low in the sky the atmosphere is the thickest giving us the beautiful colours of a South East Asian sunset.