Total Internal Reflection

A series of images depicting a sphere inside of a glass cube. The glass has refractive index η_glass = 1.5, and it is surrounded by water with refractive index η_water = 1.33. The viewing angle increases as we move from the top-left to the bottom-left image, clockwise. As a result, the reflection of the sky and sphere become visible near the bottom of the cube due to total internal reflection.