A strange explosion deep in space, lasting 7 hours, baffles scientists.

A 7-hour gamma-ray burst detected by NASA’s Fermi telescope is the longest ever observed, puzzling scientists and challenging current cosmic models.

A mysterious explosion lasting more than 7 hours was detected deep in the universe, in an unprecedented phenomenon that baffled astronomers, researchers announced after analyzing data captured by NASA's Fermi Gamma-ray Space Telescope.

Gamma-ray bursts (GRBs) are the most energetic explosions in the universe since the Big Bang , and on average, one occurs every day. However, what happened on July 2, 2025, was exceptional, as Fermi recorded an unusual burst that continued to release successive bursts of radiation for more than seven hours.

Astronomers quickly used observatories around the world to observe the afterglow of the explosion and determine its source.

The event was named GRB 250702B, and it turned out to be the longest gamma-ray burst ever recorded.

Researchers believe the explosion was caused by a rare or unprecedented type of cosmic event , which launched a narrow jet of matter toward the solar system, at a speed of at least 99% of the speed of light.

To understand the nature of the event, scientists used a wide range of observatories covering different wavelengths of light, including the Gemini Telescopes in Chile and Hawaii, the Very Large Telescope (VLT) in Chile, the Keck Observatory in Hawaii, and the Hubble Space Telescope.

According to NASA, gamma-ray bursts come from the depths of the universe, with the closest occurring at a distance of more than 100 million light-years.

As for GRB 250702B, it originated from a massive galaxy about 8 billion light-years away, and is characterized by being full of cosmic dust, which blocked the visible light emitted from the explosion .

Jonathan Carney, the study's lead researcher and a doctoral student in physics and astronomy at the University of North Carolina at Chapel Hill, said the event "is the longest gamma-ray burst ever observed by humans, and its length is inconsistent with any of the currently known models for explaining these bursts."