Webb telescope captures one of the most distant supernovas ever observed

The explosion, seen without the help of gravitational lensing, offers a rare look at a star's death in the young universe

By LineZotpaper

Published20 October 2026

Read Time3 min

Astronomers using the James Webb Space Telescope (JWST) have spotted what may be one of the most distant supernovas ever observed, an explosion that lit up when the universe was less than a tenth of its current age. The flash was seen as it appeared just days after the star died, more than 12.5 billion years ago.

Astronomers using the James Webb Space Telescope (JWST) have identified a supernova, named AT 2026abck, that dates to around 1.15 billion years after the Big Bang, when the universe was bursting with massive stars. The star released its light more than 12.5 billion years ago, so long ago that the expansion of the universe has stretched the distance between us roughly sixfold.

According to the study authors, whose paper was posted to the preprint server arXiv on Sept. 29 and has not yet been peer reviewed, the supernova is extraordinarily bright. "At its peak, the supernova is about 8 billion times the brightness of the sun, almost as bright as the whole Milky Way Galaxy," study co-author Xiaohui Fan, an observational cosmologist at the University of Arizona, told Live Science. "Over the course of the explosion, it radiates the energy that the sun will radiate over about 2 billion years."

The supernova's incandescent shell has expanded to a radius of roughly 46 astronomical units, about 46 times the distance between Earth and the sun. Its host galaxy, ID101411, holds about 6.3 billion solar masses and is forming stars more than ten times faster than the Milky Way, said first author Mingyang Zhuang, an observational astrophysicist at the University of Illinois Urbana-Champaign. As with other early galaxies, it is poor in elements heavier than hydrogen and helium.

The team estimates it observed the explosion four to ten days after it ignited, a catch made possible by repeatedly scanning the same patch of sky under the NEXUS Treasury program. Most supernovas at this distance have been found with the help of massive foreground galaxy clusters acting as natural magnifying glasses; this one was observed without that aid. Zhuang described the discovery as "extremely rare" and called it "the most distant one we've actually seen appear."

The observations also showcase cosmic time dilation. JWST saw no explosion in its previous viewing on May 28, 2026, but witnessed the supernova on Aug. 7 of this year: 71 days on Earth, yet only about 12 days in the supernova's own time frame. "Changes that took one week at the supernova take about six weeks to unfold from our point of view," Zhuang said.

The explosion may be a superluminous supernova, a class that releases tens or hundreds of times more energy than conventional supernovas. The team cautioned that its interpretation remains preliminary. "Follow-up observations will tell us more about exactly what kind of explosion this was," Zhuang said.

Analysis

Why This Matters

The sighting opens a direct window onto star death in the universe's first 1.15 billion years, a period when galaxies like ID101411 were forming stars at furious rates.
Because it was seen without the aid of gravitational lensing, it suggests JWST surveys can catch ancient explosions on their own, rather than relying on cosmic magnifying glasses.
The apparent slow motion of the explosion is a vivid demonstration of cosmic expansion stretching time as well as space.

Background

The James Webb Space Telescope is an infrared observatory built to study the early universe, including the first galaxies and the stars within them. Supernovas are the explosive deaths of massive stars and serve as bright beacons visible across vast distances. Because the universe has expanded since this light was emitted, distant events appear to unfold in slow motion from our perspective, with their light stretched toward longer wavelengths.

Key Perspectives

The discovery team: The researchers emphasize that luck played a large role, since the explosion had to occur in a patch of sky already under repeated observation. They stress that their classification is preliminary and depends on follow-up observations. The wider astronomical community: With the paper still on arXiv, the findings await peer review, and other researchers will have the chance to scrutinize the data and test the analysis. Skeptics and cautious readers: Until those checks are complete, the supernova's status as one of the most distant ever seen, and its possible classification as superluminous, should be treated as provisional.

What to Watch

Whether follow-up observations show the explosion heating up or cooling down, which could reveal what is happening in its environment and what caused it.
Whether the paper passes peer review and whether distance and brightness estimates hold up under scrutiny.
Whether other young, unlensed supernovas emerge as the NEXUS program continues to scan the same patches of sky.

Sources

The James Webb telescope is watching one of the earliest supernovas in the universe unfold · Latest from Live Science

Checked

12 claims in this story checked against 1 source: 11 supported.

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Partly supportedThe headline says Webb captured one of the most distant supernovas ever observed, without the source’s uncertainty.Latest from Live Science: “Astronomers using the James Webb Space Telescope ( JWST ) have found what may be one of the most distant supernovas ever observed.”
SupportedThe summary says the supernova was observed without gravitational lensing, offering a rare look at a star’s death in the young universe.Latest from Live Science: “There’s another layer of luck that made the discovery even more remarkable: It was observed without the aid of a cosmological quirk called gravitational lensing”
SupportedThe flash was seen just days after the star died, more than 12.5 billion years ago.Latest from Live Science: “The study authors estimate that they observed the supernova as it would have looked just four to 10 days after it exploded.”
SupportedFan said the supernova was about 8 billion times as bright as the sun, almost as bright as the Milky Way, and radiated the energy the sun emits over about 2 billion years.Latest from Live Science: ““At its peak, the supernova is about 8 billion times the brightness of the sun … almost as bright as the whole Milky Way Galaxy,” study co-author Xiaohui Fan”
SupportedZhuang called it “the most distant one we've actually seen appear.”Latest from Live Science: ““It’s the most distant one we’ve actually seen appear.””
SupportedThe supernova dates to around 1.15 billion years after the Big Bang, when the universe was less than one-tenth its current age.Latest from Live Science: “The supernova, named AT 2026abck, dates to around 1.15 billion years after the Big Bang, when the universe was less than one-tenth of its current age”
SupportedThe star released its light more than 12.5 billion years ago, and cosmic expansion has stretched the distance between us roughly sixfold.Latest from Live Science: “The massive exploding star violently released its light over 12.5 billion years ago, according to the researchers — so long ago that the distance between us has effectively ballooned sixfold”
SupportedThe supernova’s shell has expanded to a radius of roughly 46 astronomical units, about 46 times the Earth–Sun distance.Latest from Live Science: “Its incandescent shell of ejected material has billowed to a radius of approximately 46 astronomical units — about 46 times the distance between Earth and the sun”
SupportedThe host galaxy has about 6.3 billion solar masses and is forming stars more than ten times faster than the Milky Way.Latest from Live Science: “The supernova's host galaxy, designated ID101411, holds about 6.3 billion solar masses and is “forming new stars more than ten times faster than our Milky Way,””
SupportedThe team estimates it observed the explosion four to ten days after it ignited, through repeated scans under the NEXUS Treasury program.Latest from Live Science: “The study authors estimate that they observed the supernova as it would have looked just four to 10 days after it exploded.”
SupportedJWST saw no explosion on May 28, 2026, then saw the supernova on Aug. 7; 71 Earth days corresponded to about 12 days in the supernova’s time frame.Latest from Live Science: “Intriguingly, the star had not yet exploded in JWST’s previous viewing, on May 28, 2026, meaning that 71 days passed on our Earthly clocks, even though only about 12 days passed in the supernova’s own time frame.”
SupportedThe team says the supernova may be superluminous and that its interpretation remains preliminary.Latest from Live Science: “the recently discovered supernova may be one of the universe's rarest, most powerful explosions, the study authors said. Known as a superluminous supernova”