Galaxy Cluster Abell 2218

The Hubble Space Telescope imaged this giant, cosmic magnifying glass, a massive cluster of galaxies called Abell 2218. The cluster is so massive that its enormous gravitational field deflects light rays passing through it, much as an optical lens bends light to form an image. This phenomenon, called gravitational lensing, magnifies, brightens, and distorts images from faraway objects. The cluster's magnifying powers provides a powerful "zoom lens" for viewing distant galaxies that could not normally be observed with the largest telescopes. This useful phenomenon has produced the arc-shaped patterns found throughout the Hubble picture. These arcs are the distorted images of very distant galaxies, which lie 5 to 10 times farther than the lensing cluster.