The Bullet Cluster (1E 0657-56) consists of two colliding clusters of galaxies. Strictly speaking, the name Bullet Cluster refers to the smaller subcluster, moving away from the larger one. It is at a comoving radial distance of 1.141 Gpc (3.72 billion light-years). The first known reference to this cluster comes from a 1992 paper titled, "The Einstein Slew Survey". The object is of a particular note for astrophysicists, because gravitational lensing studies of the Bullet Cluster are claimed to provide strong evidence for the existence of dark matter. Observations of other galaxy cluster collisions, such as MACS J0025.4-1222, similarly support the existence of dark matter.
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This article is an automated import of the Wikipedia article "Bullet Cluster", available at https://en.wikipedia.org/wiki/Bullet_Cluster . Text is licensed under CC BY-SA 4.0.