JWST's Discoveries Illuminate Early Universe Mysteries.

NASA's James Webb Space Telescope (JWST) has discovered over 700 galaxies from one of the earliest periods of the universe, dating back to when the universe was less than 600 million years old. The telescope's Near-Infrared Spectrograph (NIRSpec) was used to look for spectral signatures of star formation in regions dating to near the epoch of reionization, and astronomers found a high proportion of hot, massive stars, indicating that they were the primary cause of reionization. Before the JWST, only a few dozen galaxies from this period of cosmic history had been uncovered.