Looking at the earliest galaxies

22. An international team of astronomers led by EPFL have discovered over 250 of the universe's earliest galaxies. This sample includes the faintest and smallest of the first-generation dwarf galaxies to be discovered, and offers important clues about the nature of the early universe. Before light travelled across it, the universe was a dark place. For about a billion years after the Big Bang, the cosmos was cloaked in a thick fog of hydrogen gas that kept light trapped. But as early stars began to form, hydrogen began to clear through a process called "reionization", leting light escape in all directions and turning the universe transparent. This event played a central role in the formation of the universe as we know it.