Chandra Release - August 21, 2006

Visual Description: 1E 0657-56

This image is a composite image of the Galaxy Cluster 1E 0657-56, also known as the Bullet Cluster. The galaxy cluster is composed of hundreds of galaxies that are held together by their mutual gravitational attraction. In the image, we can see a large number of gold and white dots and tiny spiral shapes scattered across a dark background. These sources represent individual galaxies within the cluster. The most prominent features of the image is the large bright pink cloudy object in the center overlaying dozens and dozens of the galaxies, which is brighter and more concentrated and is shaped like a very large bullet. The bullet-shaped clump on the right side is the hot gas from one cluster, which passed through the hot gas from the other larger cluster during the collision.  On either side of the large pink bullet are blue cloudy areas where astronomers find most of the mass in the clusters. The concentration of mass is determined using the effect of so-called gravitational lensing, where light from distant objects is distorted by intervening matter. Most of the matter in the clusters (blue) is clearly separate from the normal matter (pink), giving direct evidence that nearly all of the matter in the clusters is dark matter.