The models gradually got better over time, until the SXS team was able to simulate what a double black hole impact might look like to the naked eye. They placed two imaginary black holes in front of the Milky Way in their simulation. Then they tracked each ray of light as it moved through the system to produce step-by-step images of the process. If you watch the animation below, you can see points of light appearing, disappearing, and seeming to shift around. In fact, the stars are staying still--but the light streaming from them twists, splits, and spins around the black hole. The resulting circular clusters are known as "Einstein Rings."