Nearly invisible 'ghost galaxy' made of 99% dark matter discovered

Astronomers using NASA's Hubble Space Telescope discovered a nearly invisible "ghost galaxy" called CDG-2 that is composed of about 99% dark matter. Located roughly 300 million light-years away in the Perseus cluster, the galaxy was detected by spotting four tightly packed globular star clusters. The discovery offers a new way to find ultra-dim galaxies hidden in space.