Celestial Cities and the Roads That Connect Them
Galaxies across the universe reside in cosmic communities big and small. Large, densely populated galactic communities are called galaxy clusters (highlighted in the orange circle). Like cities on Earth, galaxy clusters are scattered throughout the universe and are connected by a web of dusty highways called filaments (highlighted in purple). Smaller galactic communities are sprinkled along the filaments, creating celestial suburbs.
Over time, astronomers suspect that all galactic suburbanites make their way to a galaxy cluster by way of filaments. Observations from NASA's Spitzer Space Telescope show that filamentary galaxies form stars at twice the rate of their densely clustered counterparts.