Both a tan and a burn result from exposure to ultraviolet light.
Excessive exposure to ultra violet light can lead to sun burn, skin cancer, and depending on the wave length of the light, cataracts. These conditions are not generally considered to be good for you.
Skin
A burn on the skin caused by excessive exposure to the sun or other sources of ultraviolet-A and -B radiation.
The Earth's ozone layer blocks the ultraviolet light and protects the living organisms from the harmful UV rays. If it didn't, then everyone would burn up, we wouldn't be living, Earth would just be a rock floating through space.
Ultraviolet (UV) light from the sun would burn the Earth if the ozone layer has a hole. The ozone layer acts as a shield, protecting the Earth from harmful UV radiation. Without this protection, increased exposure to UV light can lead to various consequences like skin cancer, cataracts, and damage to marine life.
Sun burn.
Burning magnesium emits ultraviolet light, which can damage your eyes.
In general, it is ultraviolet light (the UV ray) that causes sunburn. Ultraviolet light is of a higher frequency than visible light, which means shorter wavelength, and higher energy. UV rays tend to do some tissue damage and burn skin causing sunburn.
Common sources of burns include hot liquids (scalds), flames from fires, contact with hot surfaces or objects, and electrical sources. Chemical burns can occur from exposure to corrosive substances like acids or alkalis. Additionally, sunburns result from prolonged exposure to ultraviolet radiation. Each type of burn varies in severity and treatment depending on the source and duration of exposure.
Ultraviolet
That makes you have a sun burn
A sunburn manifested by cutaneous redness, swelling and pain is an acute toxic reaction caused by exposure to the sun's ultraviolet radiation. Although the precise mechanism by which a sunburn occurs has not been clearly identified, complex chemical reactions and pathways take place that most likely result in the clinical symptoms.