The James Webb Space Telescope was called the “First Light Machine” when it was being studied as a potential NASA mission. It quickly became obvious that it would be impossible to prove that the “first” galaxy had been seen, but much more promising was looking for the most distant galaxies possible. This goal led astronomers to design a suite of instruments for the telescope that are optimized for looking for very faint galaxies at infrared wavelengths — infrared is required because the expansion of the universe moves the ultraviolet-visible output of galaxies to longer wavelengths. Scientists have succeeded at finding galaxies seen at an age of only 290 million years after the Big Bang. Such distant galaxies are proving to have unexpected properties that challenge our ideas of how stars are formed in these first galaxies. 

Speaker Marcia J. Rieke is Regents Professor of Astronomy and Dr. Elizabeth Roemer Endowed Chair of the Steward Observatory at the University of Arizona.