Tanning Tanning Sunlight is made up of many different waves or rays. One group of sunlight rays is visible light.
Visible light is safe and necessary for life.
Most of the other sunlight rays are dangerous. The majority of these are blocked by the earth's atmosphere. The part of the atmosphere that blocks many of these dangerous rays is the ozone layer. X-rays and gamma rays are examples of dangerous sunlight rays which are completely blocked by the ozone layer. Other dangerous rays such as ultraviolet light are only partially blocked by the ozone layer.