text: Motions in Nearby Galaxy Cluster Reveal Hidden Superstructure Chandra X-Ray Observatory -- A nearby galaxy cluster is facing an intergalactic headwind as it is pulled by an underlying superstructure of dark matter, according to new evidence from NASA's Chandra X-ray Observatory.     Astronomers think that most of the matter in the universe is concentrated in long large filaments of dark matter and that galaxy clusters are formed where these filaments intersect...