What is sunlight?

 

Inside the sun, a core fusion process heats the sun’s surface up to a temperature of approximately 5500ºC. This temperature causes the sun to emit radiation: “sunlight”.

Sunlight consists of various colours which have different levels of energy. About 45% of the light emitted consists of visible light, or light that we can observe with our eyes. In addition to this visible light, sunlight also contains light that we cannot see: known as ultraviolet light (UV: very high energy and harmful to people) and infrared light (IR: very low energy, and therefore penetrates well).

The sun also emits some x-rays and microwaves, in relatively small quantities. However, not all light reaches us on earth. This is because of the shielding effect of the earth’s atmosphere. The atmosphere contains a wide variety of gases, each of which absorbs a specific range of sunlight. For instance, ultraviolet light is absorbed by the ozone layer, and infrared light by water vapour to a significant degree.