Why Does a Body Go Red When Sunburned?

A tan is the creation of particles of melanin by special cells in the body.  These are like little sun shades the cells create to keep the sun away and stop the rays from burning the cells hiding under them.  If the skin already has some melanin in it, then the cell will work to darken the particles to increase the shade they provide.  

For a more scientific understanding of melanin please go to the website where we have several papers on the subject from leading experts in the field.