UVA, UVB and even UVC - does it really matter to U? Actually, the different wavelengths of the sun's rays do matter when it comes to your skin. Ultraviolet radiation is the light that reaches earth from the sun. First, cross UVC rays off the list - they don't have a significant impact. UVB rays are the ones that react with melanin in your skin to tan or burn it, and that's a direct way to measure skin damage...