The Bullet Cluster

This view of the Bullet Cluster is a combination of X-rays from NASA's Chandra Observatory (shown in red) and optical data from the Hubble and Magellan telescopes (shown in yellow). If some of the gas in the Bullet Cluster had particles of antimatter, they would annihilate with matter and possibly could be detected. However, the observed amounts of X-rays and the non-detection of gamma rays show that the fraction of antimatter in the Bullet Cluster is less than three parts per million.