Few things in the universe are as perplexing as dark matter — the invisible and exotic “stuff” that is thought to make up most of the matter in galaxies.

The theory goes like this: To reconcile our current understanding of physics with what we observe in the cosmos, there must be massive amounts of matter that we can’t see. Scientists are sure that this “missing matter” exists because of the gravitational effects it exerts, but detecting it firsthand has eluded scientists, who have had to indirectly infer how dark matter occupies the universe.