 In 2014, a team of astronomers found a supernova in this galaxy cluster, over 5 billion light years away. The supernova actually happened in a galaxy 4 billion light years beyond that, making it 9 billion light years away. The huge mass of the foreground galaxy and galaxy cluster bent the light from the distant supernova, creating four separate images of the same explosion. The images are arranged around an elliptical galaxy in a formation known as an Einstein Cross. Following this discovery, astronomers modeled several possible gas and dark matter distributions in the galaxy cluster. Each model predicted that another image of this supernova will appear in the cluster, but they had different time estimates ranging from 2015 through 2025. In December 2015, it appeared. For the first time in history, the time and location of a supernova was accurately predicted. We actually saw the supernova happen. Instead of detecting a flash in the sky and turning telescopes to its location, we had the telescopes already focused on the correct area and recorded the event from beginning to end. This was powerful evidence for dark matter.