File:Gravitational Lens G2237 + 0305.jpg

English: This early Hubble Space Telescope image of gravitational lens G2237 + 0305 — sometimes referred to as an "Einstein Cross" — shows four images of a very distant quasar which has been multiple-imaged by a relatively nearby galaxy acting as a gravitational lens.

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 image. The bright central region of the galaxy is seen as the diffuse central object. The image was taken in 1990.

Gravitational lensing occurs when the light from a distant source passes through or close to a massive foreground object. Depending on the detailed alignment of the foreground and background objects with the line of sight to Earth, several images of the background object may be seen.

For more information, visit: hubblesite.org/news_release/news/1990-20

Credit: NASA, ESA, and STScI