Looking in the universe is like looking through time. And this has led the astronomers from Arizona State University and MIT to find out about the time when the first stars light up-which was just 180 million years after the Big Bang. Astronomers call it the “Cosmic Dawn”. In early years, universe was in total darkness. This phase is generally referred to as the “Cosmic Dark Ages”. It was a phase when universe was a very cold and a very dark place. It consisted of only hydrogen gas, which made up the majority of the interstellar medium. Yet it was indistinguishable from all the cosmic radiation that was left behind by the Big Bang. But time passed and the matter started clustering together; it grew larger and exerted enough pressure to start nuclear fusion. And this is how the first stars in our universe flickered! The UV radiation emitted by these stars reacted with the hydrogen in the surrounding and it’s this reaction which was observed now! Diff...