Let’s start with the sun. As you may be aware, it emits visible light (which helps us see) and infrared radiation (which warms our bodies and planet). It also emits ultraviolet radiation in three forms, conveniently named ultraviolet A (UVA), ultraviolet B (UVB), and ultraviolet C (UVC). Thanks to our atmosphere blocking virtually all of the UVC, most of us need only be concerned with the first two, namely UVA and UVB.

Interestingly, our skin does a great job at shielding our insides from the sun’s harmful rays. If our skin weren’t there, we would all be developing internal cancers at a young age (we would also look grotesque).

Great, so skin protects us. In so doing, however, it unfortunately acquires some damage. The sun’s UVB penetrates into the outermost layers of the skin, while its’ UVA penetrates into the deeper layers. The pigment in our skin cells (called melanin) helps absorb and reflect some of the rays. With higher, sustained doses of ultraviolet light, our skin cells enhance the production of melanin, but at a certain point, they cannot keep up.

So, then what happens? Most importantly, the DNA in our skin cells reluctantly absorbs the radiation. This event is thought to be the main reason we make skin cancers, including basal cell carcinoma, squamous cell carcinoma, and melanoma.
Secondly, the radiation creates chemicals called free radicals, which eventually erodes the support structure in our skin. This results in wrinkled, less elastic skin, making us look older than we should.