June 22, 2011: A team of scientists studying the galaxy cluster
Abell 2744, nicknamed Pandora's Cluster, have pieced together
the cluster's complex and violent history using telescopes in
space and on the ground, including the Hubble Space Telescope,
the European Southern Observatory's Very Large Telescope, the
Japanese Subaru telescope, and NASA's Chandra X-ray Observatory.
The giant galaxy cluster appears to be the result of a
simultaneous pile-up of at least four separate, smaller galaxy
clusters that took place over a span of 350 million years. The
galaxies in the cluster make up less than five percent of its
mass. The gas (around 20 percent) is so hot that it shines only
in X-rays (colored red in this image). The image is a composite
of separate exposures made by Hubble Space Telescope Advanced
Camera for Surveys detectors in October 2009, the VLT, and the
Chandra ACIS detector. Hubble provides the central, most
detailed part of the image, while the VLT, which has a wider
field of view, provides the oute