How did the discovery of gravitational lensing affect our knowledge of quasars?
A)It showed that some quasars are located within the Local Group of galaxies.
B)It showed that quasars are located in the halo of the Milky Way.
C)It showed that quasars are much farther away than the distant galaxies that form the gravitational lenses.
D)It proved the existence of super-massive black holes at the centres of active galactic nuclei.

Question

Quizplus · Accepted Answer

The discovery of gravitational lensing showed that quasars are much farther away than the distant galaxies that form the gravitational lenses. This is because the gravitational lensing effect occurs when light from a distant object, such as a quasar, is bent and magnified by the gravity of an intervening massive object, such as a galaxy. The fact that quasars can be gravitationally lensed by galaxies located much closer to us than the quasars themselves suggests that quasars are extremely distant objects.

How Did the Discovery of Gravitational Lensing Affect Our Knowledge