This is what causes freckles, sun spots, and other brown spots. The photos, taken using ultraviolet light, show the clumping of the pigmentation that is not yet visible on the surface ...

NGC 7293, aka the Helix Nebula, is located about 700 light-years away in the constellation Aquarius, and belongs to a class ...

We cannot see ultraviolet (UV) light but it can have ... X-rays are absorbed by dense structures like bones, which is why X-ray photos are used to help identify broken bones.