X-Rays: Bones on Display

Wilhelm Roentgen discovered X-rays in 1895 and immediately took a radiograph of his wife's hand. She reportedly said, "I have seen my death" upon seeing her skeleton.

This is why X-rays are perfect for medical imaging — bones block the rays and appear white on film, while flesh lets them through and appears dark. But X-rays carry enough energy to damage DNA, which is why technicians leave the room and patients wear a lead apron.