Gravitational Lensing

Gravitational Lensing occurs when there is a massive body with massive gravity between the object and the observer. The light coming from the object is distorted due to the gravity of the massive body.

Einstein observed that the sun bent the light of distant objects when their light passed close to it, and this was the proof for general relativity. There are three types of lensing:

Strong Lensing produces multiple images of the same object. In 1985, four quasars were discovered close to each other, but it turned out there was just one quasar lensed by a galaxy which made it look like four. It was called Einstein's Cross.

In Microlensing, there is no distortion. Instead, a star closer to us bends and amplifies the light coming from a distant star. Any exoplanets that orbit the closer star also add to the lensing and amplifies the light, This is also one method to detect exoplanets.

Weak Lensing produces a stretched or deformed image of the object. It magnifies the object by increasing the amount of light and makes those galaxies visible that we would otherwise not be able to see.