Galaxy Cluster Abell 370

This image shows a massive galaxy cluster embedded in the middle of a field of nearly 8,000 galaxies scattered across space and time. This "galaxies galore" snapshot is from a Hubble Space Telescope survey to enlarge the area around huge galaxy clusters previously photographed by Hubble. In this view the huge cluster Abell 370, located about 4 billion light-years away, lies in the center of this image. It contains several hundred galaxies. Massive galaxy clusters like Abell 370 are mainly composed of dark matter. Their large masses distort space, turning them into gravitational lenses that magnify and distort the light coming from distant background galaxies. This allows the discovery of background galaxies and supernovas that are so distant and faint that they could not have been photographed by Hubble without the aid of this additional gravitational amplification.