Astronomers have spotted a galaxy so faint, it’s almost invisible — a discovery that could help illuminate one of the most elusive substances in the universe.The researchers found Candidate Dark Galaxy-2, or CDG-2, using the Hubble Space Telescope, and they believe it’s made of at least 99.9% dark matter. If their finding is backed by further observations, CDG-2 would be one of the most dark matter-heavy galaxies ever found.Dark matter dominates the universe. It is five times more abundant than regular matter — which is what all stars, planets and everything else that we can see is made of — but it is invisible and has never been directly observed.AdvertisementAdvertisementHowever, its presence can be inferred due to its gravitational effects on regular matter because dark matter is the glue that holds the universe together.Most galaxies, including our own, are dominated by dark matter. But in some cases, the ratio of dark matter to normal matter becomes so extreme that a galaxy is left with only sparse stars, making it appear very faint. Astronomers call these bodies “low surface brightness galaxies,” and have observed thousands of them since the first one was discovered in the 1980s.CDG-2, which is about 300 million light-years from Earth, appears to be so rich in dark matter that it could belong to a hypothesized subset of low surface brightness galaxies called “dark galaxies,” which are believed to contain few or no stars. “Low surface brightness galaxies are very faint, but there’s still some light coming from them,” said Dayi Li, a post-doctoral fellow in statistics and astrophysics at the Univ …
