The blue colour of the sky is a natural phenomenon caused by the interaction between sunlight and gases and particles in the Earth’s atmosphere.
Although sunlight appears white to the human eye, it is actually made up of different colours.
When sunlight enters the Earth’s atmosphere, it interacts with tiny air molecules, causing the light to scatter in different directions.
Blue light has a shorter wavelength than red and yellow light, meaning it is scattered more strongly by the atmosphere. This is why the sky appears blue when we look up during the day.
At sunrise and sunset, sunlight has to travel a longer distance through the atmosphere. As a result, much of the blue light is scattered away, allowing red, orange and yellow colours to become more visible.
This phenomenon is known in physics as Rayleigh scattering.
