Newly Detected Supernova Exploded When the Universe Was Just 730 Million-Years-Old

The universe is almost 13.8 billion years old, but every now and then, astronomers detect echoes from its distant past.

One such occasion occurred earlier in 2025, when NASA scientists reported sightings of a supernova that exploded when the universe was just 730 million years old — beating the previous record by over a billion years.

“There are only a handful of gamma-ray bursts in the last 50 years that have been detected in the first billion years of the universe,” lead author Andrew Levan, professor at Radboud University in Nijmegen, the Netherlands, and the University of Warwick in the U.K., said in a statement. “This particular event is very rare and very exciting.”

Indeed, this is the earliest supernova observed to date — and unexpectedly, it looked surprisingly similar to more recent and more local events. The observations have been described in Astronomy and Astrophysics Letters.

Read More: First-Ever Binary White Dwarf System Destined to Explode as Type 1a Supernova

Detecting “Very Rare” Gamma-Ray Bursts

The first hint that something unusual was taking place occurred on March 14, 2025, when the Space Variable Objects Monitor satellite observed a long gamma-ray burst. An infrared afterglow was subsequently reported by the Nordic Optical Telescope, and an X-ray counterpart was detected by both the Swift X-Ray Telescope and the Einstein Probe Follow-up X-ray Telescope.

Gamma-ray bursts are a spate of very bright flashes lasting anywhere between a hundredth of a second to ninety minutes, but usually no longer than a few minutes, according to the European Space Agency (ESA). Boasting the smallest wavelength and requiring more energy than any other wave on the electromagnetic spectrum, gamma rays are only produced by extremely hot, extremely energetic objects — think: nuclear explosions, pulsars, and, of course, supernovae.

To put into perspective just how much energy is contained within a single gamma-ray burst, NASA explains that just 10 seconds can release more energy than the sun will discharge over its lifetime.

Linking Gamma-Rays and Supernovae

The fact that this particular gamma-ray burst lasted longer than a few seconds enabled astronomers to link its detection to a supernova — a phenomenally bright explosion that marks the dramatic death of a massive star.

As per the study’s authors, “The majority of long-duration gamma-ray bursts (GRBs) are thought to arise from the collapse of massive stars, making them powerful tracers of star formation across cosmic time.”

Subsequent observations, collected by the James Webb Space Telescope on July 1, show a “likely” supernova and its host galaxy. Unlike typical supernovae that gradually brighten over weeks before dimming, this supernova brightened over months. This is down to the timing of its explosion. Because the explosion occurred during the early universe, the light it emitted stretched as the universe continued to expand.

“Exactly Like Modern Supernovae”

The early universe was a very different place from how it is today. While much of it remains a mystery, it is thought that the early stars that populated the first galaxies were far bigger than modern stars, with theory suggesting they could be up to 300 times as large as the sun, according to NASA.

These stars are also thought to have been incredibly short-lived, surviving just a few million years before exploding. (In comparison, our sun has a predicted life expectancy of 10 billion years.) This meant early stars were also astonishingly bright.

As such, the researchers were prepared to notice striking differences between this supernova and a more recent supernova that occurred closer to home. But this was not the case.

“We went in with open minds,” co-author Nial Tanvir, a professor at the University of Leicester in the U.K., said in a statement. “And lo and behold, Webb showed that this supernova looks exactly like modern supernovae.”

The researchers found the star that caused the gamma-ray burst was “not much more massive” and may even have looked similar to those in our local universe.

“If correct, this would imply a rather limited scope for the evolution in the GRB [gamma-ray burst] and SN [supernovae] properties across much of cosmic history,” the study’s authors wrote.

Read More: Two Nova Explosions Reveal Never-Before-Seen Structures in Stellar Blasts

Article Sources

Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:

• This article references information from the recent study published in Astronomy and Astrophysics: JWST reveals a supernova following a gamma-ray burst at z ≃ 7.3
• This article references information from the ESA: Gamma-ray Bursts
• This article references information from NASA: Gamma Rays
• This article references information from NASA: Early Universe