Gravitation lens G2237+0305. Einstein Cross quasar. A gravitational lens occurs when light from a very distant, bright source (such as a quasar) is bent around a massive object (such as a galaxy) situated between the source object and the observer. The process is known as gravitational lensing, and was predicted by Einsteins theory of general relativity. When the lensing effect is very strong, distortionpccurs creating multiple images of the source, as in this example.