The most distant and oldest starlight ever seen was detected by NASA’s $10 billion space telescope just days into its live science operations last summer, it’s been confirmed.
The James Webb Space Telescope (JWST) found an “undiscovered country” of early galaxies existing close to the Big Bang 13.8 billion years ago—the beginning of the Universe—that no previous instrument had previously detected. It was able to do so because it’s uniquely built to detect ancient infrared light that’s been stretched over space and time.
The two ancient galaxies were found billions of light-years behind a giant galaxy cluster called Abell 2744. These first galaxies look very different to those seen close to the Milky Way that the likes of the Hubble Space Telescope can see in visible light. The two most important discoveries from the GLASS-JWST Early Release Science Program and Cosmic Evolution Early Release Science Survey (CEERS), the two galaxies existed just 350 to 450 million years after the Big Bang. Papers from both GLASS and CEERS were published this week in the Astrophysical Journal Letters.
Both galaxies appear to be intriguingly compact—just 1% the size of our Milky Way galaxy—spherical and bright, and rapidly birthing stars. It’s thought that they were forming stars just 100 million years after the Big Bang. This insight was only made possible by JWST’s ultra-sharp images in infrared light. “These galaxies are very different from the Milky Way or other big galaxies we see around us today,” said Tommaso Treu of the University of California at Los Angeles, a co-investigator on one of the Webb programs. “Everything we see is new.”
JWST’s immediate discoveries have left astronomers perplexed. “These galaxies would have had to have started coming together maybe just 100 million years after the Big Bang,” said Garth Illingworth of the University of California at Santa Cruz. This primal Universe would have been just one hundredth of its current age. “Nobody expected that the dark ages would have ended so early.”
One theory is that these bright galaxies are massive with lots of low-mass stars. Another is that they’re less massive but have fewer very bright (so-called Population III) stars. The latter theory, if true, would mean JWST has already detected the first stars ever born
“This is a whole new chapter in astronomy—it’s like an archaeological dig, when suddenly you find a lost city or something you didn’t know about,” said Paola Santini, fourth author of the GLASS-JWST paper. “It’s just staggering.”
Wishing you clear skies and wide eyes.