The sun's dangers
The sun gives off a variety of light rays that reach the Earth: ultraviolet (UV) rays, visible light and infrared radiation. UV rays represent only a small fraction of the solar energy we receive, but they have a major impact on skin. Ultraviolet radiation can be divided into several categories, depending on its wavelength:
- UVA rays, which have the longest wavelengths, are responsible for quick tanning but also for skin ageing and wrinkles, because they penetrate deeply into skin tissue and cause damage.
- UVB rays, which have a medium wavelength, are responsible for slow tanning, sunburn, ageing of the skin and also skin cancer. They are extremely hazardous to the body.
UVC rays, which have the shortest wavelengths, are the most harmful. Fortunately, these rays do not reach the Earth’s surface, because they are absorbed by the atmosphere.