The Perseus Galaxy Cluster (IMAGE) NASA/Goddard Space Flight Center Caption The Perseus galaxy cluster, located about 240 million light-years away, is shown in this composite of visible light (green and red) and near-infrared images from the Sloan Digital Sky Survey. Unseen here is a thin, hot, X-ray-emitting gas that fills the cluster. Credit Robert Lupton and the Sloan Digital Sky Survey Consortium Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.