An international team of astronomers using NASA’s Hubble Space Telescope has studied a filament of dark matter in three dimensions for the first time. This Hubble image shows the massive galaxy cluster MACS J0717.5+3745. The location of the dark matter is revealed in a map of the mass in the cluster and surrounding region, shown here in blue. The filament visibly extends out and to the left of the cluster core (NASA / ESA / Harald Ebeling / University...
