In Space, There Is No Up or Down
Former ISS astronaut André Kuipers took this photo of an air bubble inside of a water droplet on a previous expedition, proving that hanging out in space is every bit as fun as you’d imagine it is. But he also provides us with a fun way to illustrate a physical principle of light and optics: refraction.
When light passes from one medium to another, like air-to-water or water-to-air, it is bent. Different wavelengths are bent at different angles in different media depending on the angle of the light hitting the interface between, say, air and water. It’s all laid out in something called Snell’s Law, if you’re interested.
So light from André’s particularly shiny noggin is bent down when it enters the water, and light from his chin is bent up. And when the light waves in water re-enter the air, the whole process is flipped again thanks to inverse refraction.
The result is a man with a squashed face trapped inside a tiny bubble floating through space … and this very cool photo.