Early Universe Star Formation Galaxy Evolution Galaxy Mergers Early Galaxies Cosmology Redshift Measurements Satellite Galaxies Tidal Interactions Black Hole Growth Hierarchical Structure Star Formation History Galaxy Clusters Satellite Systems Elliptical Galaxies Mergers Galaxy Classification Early Stars Distant Galaxies Small Galaxies Theories Timeline Stellar Population Lenticular Galaxies Ancient Stars Star Structures Dark Matter Halo Cosmic Dawn Stellar Evolution Early Galaxy Observation Stellar Populations Neutral Hydrogen First Generation Stars Redshift