large-scale structureThe structure of matter on the largest scales (greater than 100 megaparsecs), revealed by the results from large-scale redshift surveys of galaxies. This structure consists of very long filaments of matter surrounding huge voids or bubbles that are empty of matter. The largest superclusters are elongated, and scattered clusters of galaxies often link the ends of these superclusters into filaments. The filaments surround empty voids, the first of which was discovered in Boötes in 1981 and is about 100 Mpc across. Most of the matter in the Universe lies in the filaments, which occupy only 1% or 2% of the volume of space. The largest coherent structure so far detected in redshift surveys is the Great Wall at a distance of about 95 Mpc. This structure forms a thin sheet less than 10 Mpc thick but spans an area 80 by 225 Mpc.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006