Cosmic dawn occurred 250 to 350 million years after Big Bang

Cosmic dawn, when stars formed for the first time, occurred 250 million to 350 million years after the beginning of the universe, according to a new study led by researchers at UCL and the University of Cambridge. The study, published in the Monthly Notices of the Royal Astronomical Society , suggests that the NASA James Webb Space Telescope (JWST), scheduled to launch in November, will be sensitive enough to observe the birth of galaxies directly. Analysing images from the Hubble and Spitzer Space Telescopes, the researchers calculated the age of these galaxies as ranging from 200 to 300 million years, allowing an estimate of when their stars first formed. The UK-led research team examined six of the most distant galaxies currently known, whose light has taken most of the universe's lifetime to reach us. They found that the distance of these galaxies away from Earth corresponded to a "look back" time of more than 13 billion years ago, when the universe was only 550 million years old. Lead author Dr Nicolas Laporte (University of Cambridge), who started the project while at UCL, said: "Theorists speculate that the universe was a dark place for the first few hundred million years, before the first stars and galaxies formed. "Witnessing the moment when the universe was first bathed in starlight is a major quest in astronomy.