f reionization. Credit: NASA, ESA, and A. Feild (STScI)
Using Hubble’s newest tool, the Cosmic Origins Spectrograph (COS), researchers have nailed down and enhanced our understanding of the reionization of helium in the early Universe, clarifying the time frame of 11.7 to 11.3 billion years ago when the universe stripped electrons off from primeval helium atoms. Hubble scientists say it was the equivalent of global warming, except that a heat wave blasted through the entire early universe at that time, inhibiting the growth of small galaxies almost 500 million years.