dark galaxies

Imagine trying to find a nearly invisible ghost town in space. That's essentially what astronomers did when they discovered CDG-2. This "galaxy" is so faint that it's almost entirely made of dark matter - the mysterious invisible stuff that makes up most of the universe. The only way scientists could spot it was by noticing four very old, dense star clusters (called globular clusters) floating together in space. It's like finding four lighthouses in the fog and realizing there's an almost invisible island underneath them. What makes this discovery special is that CDG-2 is 99.9% dark matter, making it one of the "darkest" objects ever found. Most galaxies are a mix of stars, gas, and dark matter, but this one is almost pure dark matter with just a tiny bit of starlight.