Light• I had never thought that light is invisible. I know that light is a wave like sound although it does not require a medium to travel through. But I always thought that light is something we see. • I was really astonished at seeing, with my own eyes, that light is indeed invisible, and we only see the source of light and what light hits. Now I begin to understand how we see the world around us. It is like a miracle! Now I can understand why space is totally black and we see only what objects are present in it, like a spaceship or an astronaut.