Cl 0024+17 is allowing astronomers to probe the distribution of dark matter in space.

The distant galaxies appear distorted because their light is being bent and magnified by the powerful gravity of Cl 0024+17, an effect called gravitational lensing.

By mapping the distorted light created by gravitational lensing, astronomers can trace how dark matter is distributed in the cluster.

While mapping the dark matter, astronomers found a dark-matter ring near the cluster's center (although this is disputed by other independent studies[2]).

The ring's discovery is among the littlest bit evidence that dark matter exists.