Ah, the sun…no matter how badly it burns us, we always come back for more. Ever wondered what kind of damage those sunny rays can do though? Basically UV radiation damages the skin by weakening elastic collagen fibers and preventing stem cells from rejuvenating the injured area. It also helps free radicals to damage the DNA, which can lead to cancer. So soak it up if you must—it wouldn’t be summer without it, after all—but always wear a high-grade SPF and reapply every two to three hours as needed.