The period before any stars formed, when the universe was dark.
The cosmic dark ages were a period when the universe was filled with neutral hydrogen gas that blocked all light. This era began after recombination and ended when the first stars and galaxies reionized the gas, allowing photons to travel freely. It is a critical chapter in cosmic history, bridging the afterglow of the Big Bang and the birth of structure.
A comprehensive guide to the cosmic dark ages, the period when the universe was shrouded in neutral hydrogen, and how the first stars and galaxies emerged to end the darkness. This article covers the full cosmic timeline, key missions, and the evidence that shapes our understanding of this pivotal era.
The first stars emerged roughly 100–200 million years after the Big Bang, ending the cosmic dark ages. This article traces the full evolution of the universe—from the Planck epoch through inflation, recombination, and reionization—and explains how the first atoms, stars, and galaxies formed, with key evidence from COBE, WMAP, Planck, and JWST.
