By Ron Cowen
Stars congregate in galaxies, galaxies in clusters, and clusters in gargantuan assemblages called superclusters. This cosmic hierarchy prompts a question that astronomers have pondered for nearly 2 decades: Have we already discerned the largest structures in the universe, or are there greater things to come?
A new map of the heavens—the largest galaxy survey to date—reveals that superclusters are indeed the biggest objects in the universe. Instead of being disappointed, cosmologists say they’re thrilled to find evidence that structure in the cosmos maxes out.