Monday, December 29, 2008

Abell 2218: A Galaxy Cluster Lens


Picture Credit: NASA, HST, WFPC2, W. Couch (UNSW)

Explanation: Sometimes one of the largest concentrations of mass known can act like a lens. Almost all of the bright objects in this image are galaxies in the cluster known as Abell 2218. The cluster is so massive and so compact that it bends light from galaxies that lie behind it, causing many of them to appear as stretched out arcs. Many dim, elongated arcs are visible on this photograph. This picture was taken with the Wide Field Planetary Camera 2 on board the Hubble Space Telescope.

July 10, 1995

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