How Does the Sun Tan My Skin?
Sunlight tans, or darkens, your skin by causing the skin to produce extra amounts of a skin coloring pigment called “melanin.” This dark brown pigment helps protect your skin from harmful rays of the sun that would burn you.
The melanin is produced by special cells in your skin called melanocytes when exposed to ultraviolet light. When you are out in the sun, the sun is covering you with ultraviolet rays.
To protect itself, your body produces extra melanin. The result is the tanning of your skin. Instead of an even brown color, the tanning may be spotty, because the melanin is bunched up in spots. These spots are freckles.
Your body actually produces two kinds of pigment. One is called eumelanin and it is responsible for the golden brown color we normally associate with tanning.
Another pigment is called phaeomelanin and it produces a red color. Redheads and blondes produce more phaeomelanin and less eumelanin, which is why they don’t tan as well.