For the first time... a powerful and mysterious phenomenon in the universe has been observed.

 Astronomers detected a series of gamma-ray bursts, the most powerful explosions in the universe, in a single day, all coming from the same source. This is a phenomenon unprecedented and unexplained by any scenario, the European Southern Observatory announced in a statement on Tuesday.

Gamma-ray bursts (GRBs) are flashes of high-energy radiation that occur during extremely violent events, such as the death of massive stars in powerful explosions or their destruction by black holes . They typically last from a few milliseconds to a few minutes, a time period during which they can release as much energy as several billion suns.

"In theory, gamma-ray bursts never happen again because the event that produces them is destructive," Antonio Martin-Carrillo, an astronomer at University College Dublin in Ireland, said in a statement from the European Southern Observatory.

Martin-Carrillo, who co-authored a study on the subject published in The Astrophysical Journal Letters, noted that this makes the signal detected by the scientific community this summer "different from any signal detected in the past 50 years."

The first warning was issued on July 2 by NASA's Fermi Space Telescope , which detected not just one but three flashes from the same source within a few hours.

Scientists later discovered that this source had been active about a day earlier, based on data collected by the Einstein Probe, an X-ray space telescope operated by China in collaboration with the European Space Agency and the Max Planck Institute for Extraterrestrial Physics

The signal lasted "100 to 1,000 times" longer than most gamma-ray bursts , according to Andrew Levan, an astronomer at Radboud University in the Netherlands who co-authored the study.

Astronomers initially thought the gamma-ray burst originated within the Milky Way galaxy.

But observations using the European Southern Observatory's Very Large Telescope (VLT) in Chile's Atacama Desert provided evidence that the source may have come from another galaxy, a hypothesis confirmed by the Hubble Space Telescope. The host galaxy may have been several billion light-years away, meaning the event's power was significant.

The nature of the event that generated the signal remains unknown. One possible scenario is the unusual collapse of a very massive star.

Another hypothesis is that an unusual star was destroyed by an even more exotic black hole.