Narrator (April Hobart, CXC): Using a combination of powerful observatories in space and on the ground, astronomers have discovered a violent collision between two galaxy clusters. During this collision, so-called normal matter has been wrenched apart from dark matter through a violent collision between two galaxy clusters. We see the normal matter in the form of hot gas thanks to X-rays detected by the Chandra X-ray Observatory. The location of the dark matter comes from optical data that reveal the effects of gravitational lensing, something Einstein predicted where large masses can distort the light from distant objects. The new galaxy cluster is called DLSCL J0916.2+2951. Rather than say that mouthful, researchers have nicknamed it the "Musket Ball Cluster." This name makes sense because this system is like an older and slower cousin to the famous Bullet Cluster. Finding another system that is further along in its evolution than the Bullet Cluster is very valuable. It gives scientists insight into a different phase of how galaxy clusters -- the largest known objects held together by gravity -- grow and change after major collisions.
Revised: April 16, 2012