Intracluster light is diffuse light from stars that are gravitationally bound not to individual member galaxies, but to the halo of galaxy clusters. In a survey of 10 galaxy clusters as far away as nearly 10 billion light-years, astronomers found that the fraction of the intracluster light relative to the total light in a galaxy cluster remains constant, looking over billions of years back into time. These Hubble images show two massive galaxy clusters:...
