Gravitational lens. Artwork showing how gravitational lenses can enable astronomers on Earth (upper right) to see magnified views (across bottom) of distant astronomical objects. Light (dotted lines) from these distant objects usually travels in a straight line, but can be deflected by very strong gravitational fields if they pass close to a massive star, black hole, or galaxy. This deflection can magnify the image, as illustrated across top. The bending of light by massive objects was predicted by Einstein in 1916 in his general theory of relativity.