Hot gas detected by Chandra in X-rays is seen as two pink clumps that contain most of the normal matter in the two clusters. The bullet-shaped clump on the right is hot gas from one cluster, which passed through the hot gas from the other larger cluster. Other telescopes were used to detect the bulk of the matter in the clusters, which turns out to be dark matter (highlighted in blue). Credit: X-ray: NASA/CXC/CfA/M.Markevitch et al.; Optical: NASA/STScI; Magellan/U.Arizona/D.Clowe et al.; Lensing Map: NASA/STScI; ESO WFI; Magellan/U.Arizona/D.Clowe et al.
