Helium's re-ionization occurred at a transitional time in the universe's history when galaxies collided to ignite quasars.
Hubble astronomers uncover an overheated early universe
- Astronomy.com
- 11. 10 2010 (00:00)
Helium's re-ionization occurred at a transitional time in the universe's history when galaxies collided to ignite quasars.