James Webb telescope sees 'birth' of 3 of the universe's earliest galaxies in world-1st observations

For the first time ever, astronomers using the James Webb Space Telescope (JWST) may have detected some of the earliest galaxies in the known universe in the midst of being born. 

In a new study, published Thursday (May 23) in the journal Science, the researchers report the detection of what appears to be three infant galaxies sprouting from a primordial cloud of hydrogen and helium gas just 400 to 600 million years after the Big Bang. 

According to the authors, this discovery could open a window into the murky period known as the era of reionization — a time when the earliest stars and galaxies first began to pierce the dark, dense clouds of gas around them and thus reveal the transparent universe we know today.

"These galaxies are like sparkling islands in a sea of otherwise neutral, opaque gas," lead study author Kasper Heintz, an assistant professor of astrophysics at the Cosmic Dawn Center (DAWN) at the University of Copenhagen, said in a NASA statement. "Without Webb, we would not be able to observe these very early galaxies, let alone learn so much about their formation."

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In the study, the researchers used JWST to look at 12 known early galaxies dating to no more than 600 million years after the Big Bang. Back then, our now 13.8 billion-year-old universe was about 3% of its current age. The team specifically hunted for galaxies in which radiation was being absorbed by the dense clouds of electrically neutral hydrogen gas that pervaded the universe at that time. Such absorption would indicate that the galaxies were actively weaving that gas into new stars.

By looking at the ancient galaxies' spectra, or the different wavelengths of light they emitted, the team found evidence that light from three of them was being absorbed by large amounts of neutral hydrogen gas.