NASA’s Webb instrument shows how galaxies changed the early cosmos

The gas between stars and galaxies in the early cosmos was opaque, preventing intense starlight from passing through it. Nevertheless, a billion years after the great bang, the gas had totally lost its opaque nature.

Why? The cause has been identified by new data from NASA’s James Webb Space Telescope: Over hundreds of millions of years, the stars in the galaxies released enough light to heat and ionise the gas surrounding them, clarifying our collective vision.

The findings represent the most recent revelations on the era of time known as the Era of Reionization, when the cosmos underwent significant changes. The study team was directed by Simon Lilly of ETH Zürich in Switzerland. The cosmos was filled with tremendously hot and dense gas after the big bang.