This image shows the galaxy cluster Abell 1689, with the mass distribution of the dark matter in the gravitational lens overlaid (in purple). The mass in this lens is made up partly of normal (baryonic) matter and partly of dark matter. Distorted galaxies are clearly visible around the edges of the gravitational lens.
NASA/ESA/ E. Jullo -JPL/LAM/P. Natarajan-Yale and J-P. Kneib-LAM