Abell S1063 galaxy cluster, imaged by the NASA/ESA Hubble Space Telescope. Seen are a number of galaxies in the Abell S1063 cluster, which is located in the constellation Grus (The Crane). The soft blue haze is called intracluster light and is produced by stars that have been thrown out from their galaxies. These stars live solitary lives, no longer part of a galaxy but aligning themselves with the gravity of the overall cluster. Astronomers have found that intracluster light's distribution makes it a good indicator of how invisible dark matter is distributed in the cluster.