Quasar as a Gravitational Lens

Gravitational lensing is seen in when the gravitational field of a foreground galaxy causes the light from a background, distant quasar to be bent in such a way that the quasar no longer appears as a single star-like object. Sometimes multiple images of the quasar are seen. When the galaxy and quasar are perfectly aligned along our line of sight, we see an "Einstein Ring".

Suggested readings:

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