It shouldn't be too hard to figure out if your skin is healthy, right? It's just sitting there on the outside of your body. What could it be hiding?
The answer is a lot, and that's thanks to our big burning friend the sun. Take a look at how these unsuspecting people's faces look under UV light:
The project: Artist Thomas Leveritt set up a UV camera and a screen on the street and asked passersby if they wanted to check themselves out with it. The result, as you can see, was lots of freckles (and plenty of other hidden marks).
The next big surprise came when Leveritt offered them some sunscreen. Since the lotion blocks UV rays, you can see much more clearly how protective a layer can be. Watch how surprised the participants are at the difference.
The takeaway: Just like that not-written-by-Kurt Vonnegut graduation speech your grandmother forwarded you years ago, you're going to want to wear sunscreen. The Cleveland Clinic even recommends putting it on every day: "Make it a habit, such as brushing your teeth."
Too much sun exposure can give you painful and annoying sunburns, but over time it increases your risk of skin cancer. It's the most common form of cancer in the U.S., according to the CDC.
So even if you're not burning — or if you're someone who never gets burns — the sun is still taking its toll. Follow Leveritt's lead and keep yourself protected, and maybe you won't be too shocked if you ever get the chance to see yourself in UV conditions.