our science correspondent, pallab ghosh, reports. the night sky is littered with stars, but when did they first begin to shine? discovering when this critical moment — known as the cosmic dawn — began, has been this man's life's work, and now he has the answer. the holy grail has been to look back far enough that you would see the very first generation of stars and galaxies. and we've determined their ages, and that gives us the first convincing evidence of when the universe was first bathed in starlight. because we are ourselves the product of stellar evolution, in some sense, we're looking at our own origins. using telescopes from across the world, the team analysed some of the most far—away galaxies — so distant, they're just a few pixels on the computer screen. they're also among the earliest, seen not long after the creation of the universe. by working out their age, the team calculated the start of the cosmic dawn, when the first stars began to shine.