The Gravitational Lens G2237 + 0305

The European Space Agency's Faint Object Camera on board NASA/ESA Hubble Space Telescope has provided astronomers with the most detailed image ever taken of the gravitational lens G2237 + 0305, sometimes referred to as the "Einstein Cross". The photograph shows four images of a very distant quasar which has been multiple-imaged by a relatively nearby galaxy acting as a gravitational lens. The angular separation between the upper and lower images is 1.6 arc seconds.

The quasar seen here is at a distance of approximately 8 billion light years, whereas the galaxy at a distance of 400 million light years is 20 times closer. The light from the quasar is bent in its path by the gravitational field of the galaxy. This bending has produced the four bright outer images seen in the photograph. The bright central region of the galaxy is seen as the diffuse central object.