Gravitational Lensing method to measure Dark Matter

Gravitational Lensing provides us a way to measure Dark Matter in our universe

It is proven by observing images taken with Hubble Telescope that Dark Matter do exist. Sometimes it is seen that some other galaxies surround a galaxy. But actually they are not there. They are reflections of more distant galaxies coming from behind. This optical illusion is caused by Dark Matter which distorts the light. This phenomenon is called Gravitational Lensing.