Animation explaining the effect of gravitational lensing, in which the image of a distant object is distorted by the gravitational field of an object in front of it. Initially, a distant galaxy is at left, and the Earth at right. Diverging light rays from the galaxy are shown in white. If a massive object is placed in the middle, relativity predicts that the light will be bent towards the mass, in effect focussing it on Earth like a converging lens. Different arrangements produce slightly different effects. A single large mass can produce a ring with a bright central spot an Einstein ring, orange, or multiple images forming a cross an Einstein cross, blue. When the lensing object is a massive cluster of galaxies, images of the more distant galaxy are likely to be smeared into thin irregular arcs.