Part 7/10:
One of the most practical methods employed to infer dark matter's presence around galaxies is gravitational lensing. This phenomenon, predicted by Einstein, occurs when the gravitational field of a massive structure bends light from more distant objects. By observing these distortions, astronomers can infer the mass distribution of the lensing structure.
The striking discovery made through lensing is that the visible matter alone cannot account for the gravitational effects observed. This reinforces the notion that a vast halo of dark matter exists around galaxies, further corroborating both Zwicky’s and Rubin’s initial findings.