Supermassive black hole binary. Supercomputer simulation of two supermassive black holes orbiting as a binary pair, close to the point of merging. They are 30 million kilometres apart with an orbital period of 46 minutes. This simulation shows how the black holes distort the starry background and capture light, producing black hole silhouettes. A distinctive feature called a photon ring outlines the black holes. The entire system has a mass about 1 million times the Sun's. This is part of a set of simulations run in 2018 on the National Center for Supercomputing Applications' Blue Waters supercomputer at the University of Illinois at Urbana-Champaign.