Reionisation begins
Starlight starts burning the fog away, stripping electrons from hydrogen across the universe.
- When
- Known to
- ± 100 million years
- Era
- Reionisation, Stelliferous
Ultraviolet radiation from the first stars and galaxies ionises the neutral hydrogen filling space, carving expanding bubbles of transparency around each source. It is the last great phase change in cosmic history, and it reverses the recombination that made the universe neutral in the first place. The bubbles grow and overlap over the next several hundred million years.