A cosmic explosion unlike any seen before has prompted astronomers to rethink long-standing ideas about the universe’s most powerful outbursts
An international research team, including scientists from the University of North Carolina at Chapel Hill, has announced the discovery of GRB 250702B, a gamma-ray burst that remained active for nearly 7 hours.
Its unprecedented duration challenges decades of assumptions about how these events begin and why they behave the way they do.
A burst that shattered all records
Gamma-ray bursts, or GRBs, are some of the brightest explosions in the cosmos, typically erupting for only a few seconds or minutes. They occur when massive stars collapse, when dense stellar remnants collide, or through other violent cosmic processes. GRB 250702B changed that picture dramatically.
Rather than flashing and fading in moments, this gamma-ray burst persisted far longer than any previously recorded GRB. Space-based observatories first detected the event before teams around the world raced to follow its lingering glow using some of the largest ground-based telescopes available.
The long-lasting emission provided researchers with an unusually extended window to study the phenomenon.
A window into a distant, dusty galaxy
As astronomers studied the fading afterglow, they traced it to a massive galaxy billions of light-years away. This galaxy is rich in dust, which obscures visible light from the event. Only infrared and high-energy emissions were able to escape the dense material and reach Earth’s telescopes.
Data from telescopes in the United States, the European Southern Observatory’s Very Large Telescope, NASA’s Hubble Space Telescope, and X-ray observatories all contributed to a detailed picture of the explosion and its surrounding environment.
The combined observations revealed that a powerful jet had burst outward at nearly the speed of light, pushing through the dusty host galaxy and sending energy directly toward Earth.
Multiple possible origins
Despite the extensive dataset, the underlying cause of GRB 250702B is still unclear. The characteristics of the explosion do not fit neatly into any of the established gamma-ray burst classification categories.
Researchers currently consider several possibilities. One scenario involves the collapse of a massive star, an event often associated with long-duration gamma-ray bursts.
Another potential explanation is the collision of exotic stellar remnants, such as neutron stars or helium stars, which produce intense bursts of energy when they merge. A third possibility is a tidal disruption event, in which a supermassive black hole tears a star apart.
So far, no single explanation aligns perfectly with all observed features, leaving astronomers with a cosmic puzzle that will likely drive research for years.
Why this explosion matters
Gamma-ray bursts help scientists probe extreme environments where gravity warps spacetime, matter reaches extraordinary densities, and particles travel at nearly the speed of light. These events also contribute to distributing heavy elements throughout the universe.
GRB 250702B now stands as a landmark event in the study of high-energy astrophysics. Its unusual duration and complex behaviour provide a new benchmark for future discoveries.
As astronomers find additional bursts with similar properties, they will be able to compare them to this record-breaking outlier to determine whether GRB 250702B represents a rare twist on known processes or an entirely new category of cosmic explosion.
