Pandora's Cluster

Abell 2744, also known as Pandora's Cluster, is one of the most complex and dramatic collisions ever seen between galaxy clusters. This is a region 5.9 million light-years across located 3.5 billion light-years away. Many different kinds of structures are found here, including gas with temperatures in the millions of degrees.

Even though there are many bright galaxies visible, most of the mass in Pandora's Cluster comes from the vast areas of dark matter and extremely hot gas. The invisible dark matter can be made “visible” by identifying its gravitational effects on light from distant galaxies. By carefully measuring the distortions in the light a map of the dark matter's mass can be created.

Galaxy clusters are the largest known gravitationally-bound structures in the Universe, and Abell 2744 is where at least four clusters have collided together. The vast collision seems to have separated the gas from the dark matter and the galaxies themselves, creating strange effects which have never been seen together before.