In Webb’s images, the galaxies look like faint red smudges, which is why extra data, known as spectra, were critical for the team’s conclusions. Those spectra show that light from these galaxies is being absorbed by large amounts of neutral hydrogen gas. “The gas must be very widespread and cover a very large fraction of the galaxy,” said Darach Watson, a co-author who is a professor at DAWN. “This suggests that we are seeing the assembly of neutral hydrogen gas into galaxies. That gas will go on to cool, clump, and form new stars.”