Image credit: X-ray: NASA/CXC/UCDavis/W. Dawson et al; Optical: NASA/STScI/UCDavis/W. Dawson et al.

Uploader comment: Using a combination of powerful observatories in space and on the ground, astronomers have observed a violent collision between two galaxy clusters in which so-called normal matter has been wrenched apart from dark matter through a violent collision between two galaxy clusters. Finding another system that is further along in its evolution than the Bullet Cluster gives scientists valuable insight into a different phase of how galaxy clusters -- the largest known objects held together by gravity -- grow and change after major collisions.