In this illustration, green indicates ionized oxygen, while purple shows the distribution of ionized hydrogen. This galaxy — which we're observing as it was just 700 million years after the birth of the universe — shows the oldest signs of oxygen scientists have ever seen. Studying galaxies like this one in even higher resolutions may finally illuminate the dark ages of our universe. Enter the dark ages, when the universe had nothing to do but slowly bring its neutral hydrogen gas into gravity-gathered clumps. Stars ionized the gas around them — meaning they made the neutral particles charged again — in a phenomenon known as cosmic reonization.

Source: Washington Post June 17, 2016 13:05 UTC