Why does the sun look red at sun-rise and sunset？ When the sun rises and sets， it goes through a very thick layer of air and a lot of sun-light is absorbed by air. That's why it looks red. Actually， the white sunlight is formed by the seven colours of red， orange， yel-low， green， blue， indigo-blue and purple. Sometimes， a rain owmight appear in the sky. The seven beautiful colours we see are divided from the white sunlight by the rain-drops in the sky. If you paint these seven colours on a disc and turn it real fast， the colours on the disc becomes white.