The Galaxy That Cleared the Fog

For its first billion years the universe was lost in fog, a thick haze of hydrogen that swallowed light whole. Something burned it away, and astronomers have long wondered what. Now Hubble has caught a tiny, furious galaxy in the very act of clearing the murk, glimpsed as it was just 1.4 billion years after the big bang. It may be the smoking gun for how the universe first became clear.