Gravitational lensing is a phenomenon in which the gravitational force of a massive object (such as a galaxy or black hole) bends the path of light from a distant object, causing it to appear distorted or magnified.
Gravitational lensing occurs when light from a distant object travels through the gravitational field of a massive object. The gravity of the massive object bends the path of the light, causing it to appear distorted or magnified to an observer.
The two main types of gravitational lensing are strong lensing and weak lensing. Strong lensing occurs when the distorted image of the distant object is clearly visible, while weak lensing causes a slight distortion in the image that can only be detected through statistical analysis.
Gravitational lensing can help us to study the distribution of dark matter, which cannot be directly observed, as it can bend light in the same way as visible matter. It can also provide insight into the mass and structure of massive objects, such as galaxies and clusters of galaxies.
Gravitational lensing is used by astronomers to study distant objects that would otherwise be too faint or small to observe. It can also be used to study the effects of dark matter and to measure the expansion rate of the universe.