Astronomers Discovered a ‘Cosmic Fossil’ in the Making—the Most Chemically Primitive Galaxy Seen Yet—by Peering Back to the Edge of Time

The James Webb Space Telescope observed 13-billion-year-old light, using a closer galactic cluster like a magnifying glass. The work helps experts understand the universe’s earliest stars and mysterious ultra-faint dwarf galaxies

Eli Stark-Elster | AAAS Mass Media Fellow

June 18, 2026 12:41 p.m.

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For the first few hundred million years after the Big Bang, the primordial universe was draped in clouds of hydrogen and helium. Heavier elements—like carbon and oxygen, which form some of life’s basic building blocks—emerged only after those clouds fused together within the hearts of early stars.

Once, astronomers lacked telescopes powerful enough to observe the far-off and ancient regions of deep space where the formation of heavy elements began. But the launch of the James Webb Space Telescope enables them to capture the light that emanated from these stellar forges billions of years ago. According to a paper published last month in Nature, researchers have now captured traces of the most chemically primitive galaxy yet.

The new data hails from LAP1-B, a galaxy that dates to just 800 million years after the universe began. To record this distant object, the researchers needed a faint glow traveling from 13 billion light-years away, a magnifying glass jerry-rigged from the gravity of a galactic cluster and the most powerful space telescope in the history of astronomy.

Recently formed galaxies are full of elements that astronomers refer to as ‘metals’—anything heavier than hydrogen and helium. The Big Bang, however, did not produce these metals: They were generated by the combination of lighter elements inside the dense cores of stars, then scattered into space when those stars exploded as supernovas. The older a galaxy is, the fewer metals it will contain.

This is what makes LAP1-B so special. The new analysis shows that its metal concentration is roughly 1/240th the concentration found in our sun—a record low and a telltale sign that it came from the early universe. “When I first saw the spectrum of LAP1-B, I was immediately excited,” lead author Kimihiko Nakajima, an astronomer at Japan’s Kanazawa University, tells Smithsonian magazine. “The spectrum showed clear hydrogen emission lines, but almost no sign of the oxygen emission lines that are commonly observed in normal galaxies.” The apparent lack of oxygen, he says, “suggested that LAP1-B might be an extremely metal-poor system, just as we had hoped.”

Observations of LAP1-B are, quite literally, cosmological history. Like the delayed crack that emanates from the swing of a distant baseball bat, light emitted by far-off stars and galaxies does not arrive at our telescopes right away. As a result, the observations of LAP1-B show astronomers what the object looked like when its photons, or particles of light, first began their journey. The same goes for other celestial sights: The sky is a graveyard lined with cosmic fossils, and astronomers, equipped with high-grade lenses rather than shovels, dig through it to understand how the universe was made. 

Of course, fossils rarely come out of the ground pristine—as the earth surrounding them warps and erodes, so do the ancient remains. The same is true for light. As Edwin Hubble discovered in 1929, space itself is constantly expanding. In turn, it stretches the light waves that travel through it, like two ends of a Slinky being pulled in opposite directions. This effect is known as a “red shift,” because the expanding wavelength of the light moves it toward the red and infrared side of the color spectrum. The farther away a light source, the more red-shifted its light. For standard telescopes that cannot pick up highly infrared photons, this red shifting—paired with the far-off light’s dim strength—makes galaxies like LAP1-B almost invisible. 

But JWST, specifically designed to detect and record infrared light, is not standard. It sits behind a tennis-court sized sunshield, which drops the telescope’s surface temperature by nearly 600 degrees Fahrenheit, keeping its mirror and instruments colder than the surface of Pluto. In that environment, the telescope is free of interference from the sun’s warmth, keeping it highly attuned to infrared signals from deep space.

Even with these innovations, the light of LAP1-B was too faint to record directly. Fortunately, the astronomers could call upon a gravitational magnifying glass: a galaxy cluster called MACS J0416, which sits between Earth and LAP1-B. The gravity of the cluster warps the surrounding fabric of spacetime, bending and concentrating photons from light sources behind it. The team pointed JWST at this natural lens, which magnified LAP1-B by 100 times. With more than 30 hours of observations, the team calculated the amount of oxygen and other heavy elements within its distant target.

This primitive galaxy draws us closer to the beginnings of metals in the universe. As Nakajima notes, other galaxies had previously been “identified as promising candidates for chemically primitive systems.” But LAP1-B is 10 to 100 smaller than other metal-poor galaxies, he adds, and even among those, its oxygen abundance is uniquely low. “Taken together,” Nakajima says, “these properties make LAP1-B one of the most compelling laboratories currently known for studying how the first generations of stars enriched the universe.” As Evan Kirby, an astronomer at the University of Notre Dame who was not involved with the paper, tells Scientific American’s Lee Billings, “This is the galaxy that chemical evolution experts have wanted JWST to find.” 

The researchers suggest that LAP1-B confirms two long-standing predictions in astronomy. The first concerns Population III stars, the earliest generation of stars, formed from the clouds of pure hydrogen and helium generated by the Big Bang. Existing theories indicate that when these enormous stars died in supernova explosions, they scattered a specific ratio of carbon to oxygen into their surroundings. According to the analyses by Nakajima and his team, LAP1-B contains a similar signature, suggesting that Population III stars seeded the primitive galaxy with its metals. “We found that LAP1-B exhibits an unusually elevated carbon-to-oxygen ratio,” says Nakajima, “remarkably consistent with theoretical predictions for the chemical yields of Population III supernovae.”

The second prediction concerns a nearly metal-free class of galaxies known as ultra-faint dwarf (UFD) galaxies: Dominated by massive halos of dark matter and only a smattering of stars, UFDs have long been observed orbiting the Milky Way. Scientists had theorized that UFDs were the leftover, burned-out shells of earlier and more volatile galaxies that were too small to hold onto the metals ejected by their exploding stars.

LAP1-B appears to be an ancestor of these galaxies. Like UFDs, the early galaxy is extremely light in mass, nearly empty of metals and likely contains a large dark matter halo. Based on these similarities, the researchers conclude that LAP1-B is a progenitor of the UFDs seen today, making it the first such ancestor to have ever been directly observed by astronomers.

“UFDs are not only the faintest galaxies; they are composed of ancient stars over 12 billion years old and are often described as ‘fossils of the universe,’” Masami Ouchi, an astronomer at the National Astronomical Observatory of Japan and a co-author of the study, says in a statement. “Astronomers suspected they might be the remains of the universe’s earliest galaxies because they lack heavy elements, but astronomers never had a direct link—until we found LAP1-B.” 

Kirby cautions to Scientific American that “the team’s interpretations of LAP1-B … will need corroboration by future observations and other research groups.” Some astronomers have already begun that work. For instance, Nakajima and his colleagues observed rapid movement of gas in the galaxy, and they suggest that ordinary matter alone can’t account for the speed. That led them to infer the presence of a dark matter halo at the galaxy’s center, providing an extra gravitational pull. But Eli Visbal, a theoretical astrophysicist at the University of Toledo, and his colleagues proposed in another paper that the speed results instead from the outflows of dying stars. “You can’t disagree,” with the team’s measurement of the motion, Visbal tells Smithsonian magazine. “But our interpretation of that was different.”

Still, the historical import of LAP1-B is immense. “The exciting aspect,” Nakajima says, “is that LAP1-B may be only the beginning. With JWST and future facilities, we now have the opportunity to systematically search for galaxies that bridge the gap between the first stars and the more evolved galaxies that we observe throughout the universe today.”

Eli Stark-Elster | Read More

Eli Stark-Elster is the AAAS Mass Media Science & Engineering Fellow at Smithsonian magazine. He is a PhD student in evolutionary anthropology at the University of California, Davis. His research focuses on documenting the methods used to induce altered states of consciousness across cultures—he conducts fieldwork in southern Africa, where he studies the shamanic use of hallucinogenic plants and fungi. His writing and research has been featured on NPR, Psyche and the Conversation. He also writes on his Substack, Unpublishable Papers.