About 13 billion years ago, the universe emerged from a period of darkness, ushering in a cosmic dawn. As galaxies lit up with stars, they changed the chemical composition of their surroundings, allowing light to shine clearly throughout the universe.
Looking in on that period is difficult. But with telescopes that can peer billions of light-years away — and, therefore, back billions of years in time — scientists are getting a better idea of what the universe’s early days looked like.
