Space.com: 'Spider's web' traps six galaxies around supermassive black hole

… have grown out of collections of dark matter, which is a poorly understood substance that makes up most of the matter in our universe, but can only be detected through its gravitational effects. The galaxies in the new research were only a bit easier to pick up: the astronomers required several hours of observations from several large optical telescopes, including the VLT, to study them.