This photo is of the cluster Abell 2218. The bright objects are galaxies in the cluster that are distorted into long faint arcs by a simple lensing effect that is almost like viewing street lights through a glass. Because there are so many galaxies in the cluster and it is so massive and compact, gravity bends and focuses the light from the galaxies lying behind it. A gravitational lens is formed when the light from a very distant, bright source is bent around a massive object between the source object and the observer. The cluster Abell 2218 is about three billion light years away, relatively close (NOT!), and located in the northern constellations of Draco. The power of this massive cluster telescope has lead astronomers to detect the most distant galaxy ever measured.
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