You DO use sunscreen, don’t you?
I don’t understand the science here, but an ultraviolet light camera reveals the not-yet-visible freckles that result from sun exposure. It’s interesting from a scientific point of view, and serves as a gentle reminder to use sunscreen if you want to reduce the sort of skin discolorations that will develop as you age. Don’t worry, none of the more serious results of sun exposure are shown here.
Thanks to IzaakMak for discovering this important video.