They say that this period, known as the "cosmic dawn," occurred between 250 to 350 million years after the Big Bang. The results indicate that the first galaxies will be bright enough to be seen by Nasa's James Webb Space Telescope, which is set to be launched later this year.
The study is published in the Monthly Notices of the Royal Astronomical Society. Discovering when the cosmic dawn began has been the life's work of Prof Richard Ellis, from University College London, UK.
He told BBC News: "The Holy Grail has been to look back far enough that you would be able to see the very first generation of stars and galaxies. And now we have the first convincing evidence of when the Universe was first bathed in starlight."
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The team analysed six of the most distant galaxies. They were so far away that even with the world's most powerful telescopes they appeared as just a few pixels on the computer screen. They are also among the earliest to have emerged in the Universe and so, by the time their images are captured by telescopes on Earth, they are seen not long after the Big Bang.
By working out their age, the team calculated the start of the cosmic dawn - when the first stars formed. Dr Nicolas Laporte, from the Kavli Institute of Astronomy in Cambridge led the analysis. TO READ MORE, CLICK HERE...
