Galaxy clusters are among the largest structures in our universe, consisting of hundreds or thousands of galaxies that have become gravitationally bound together over billions of years. Astrophysicists have long been eager to understand the formation of these imposing structures. The histories of galaxy clusters not only help us understand how the universe formed, but they also provide constraints on the properties of dark matter—an invisible material that doesn’t emit or reflect light and is found in high concentrations around clusters of galaxies.
Deep view of Abell 3667 illuminates the past of a galaxy cluster and the future of astronomical imaging
