A Galaxy Composed Almost Entirely of Dark Matter Has Been Confirmed

Astronomers have just identified what appears to be a cosmic anomaly: a faint galaxy with so few visible stars that, according to calculations, as much as 99.9 percent of its mass is dark matter. The remaining 0.1 percent is conventional matter.

This galaxy, located about 300 million light-years away, is practically invisible. Only four globular clusters, small concentrations of stars that look like isolated neighborhoods in the middle of the void, stand out. For years, these star collections in the Perseus cluster were considered independent objects.

Now, after an exhaustive analysis, a study published in The Astrophysical Journal Letters presents solid evidence that these globular clusters are part of the same galaxy dominated by dark matter. Tentatively named CDG-2 (Candidate Dark Galaxy-2), it is the first galaxy to be detected only by its brightest fragments.

The authors pooled data from the Hubble, Euclid, and Subaru telescopes, three of ...