According to Einstein's theory of general relativity, the presence of matter can warp space-time. This warping of space can affect the path which light-rays follow, much in the same way that a lens does. This is known as gravitational lensing.

The effect induced on the image of a distant object by a massive foreground object. Light from the distant object is bent into two or more separate images.

Banding of light from a distant object by a massive foreground object. [More Info