The Largest Structures

Galaxy clusters reveal the universe's architecture at the grandest scale:

• Clusters hold hundreds to thousands of galaxies bound by gravity and dark matter
• The intracluster medium is gas hotter than the center of a star
• Galaxies are only 3-5% of a cluster's mass; dark matter is 80-85%
• Clusters group into superclusters linked by a cosmic web of filaments
• Laniakea, our home supercluster, holds 100,000 galaxies across 520 million light-years

The cosmic web is the fingerprint of the Big Bang — tiny quantum ripples from the first instant, stretched and sculpted by gravity into the structure we see today.