Dark matter and normal matter have been wrenched apart by the tremendous collision of two large clusters of galaxies. This composite image shows the galaxy cluster 1E 0657-56, also known as the "bullet cluster." The hot gas detected by Chandra in X-rays is seen as two pink clumps in the image and contains most of the "normal" matter in the two clusters. The bullet-shaped clump on the right is the hot gas from one cluster, which passed through the hot gas from the other larger cluster during the collision. An optical image from Magellan and the Hubble Space Telescope shows the galaxies in orange and white. The blue areas in this image show where astronomers find most of the mass in the clusters.