The largest ever cosmic explosion ever witnessed has been uncovered by astronomers. 

The massive explosion is 10 times brighter than any known supernova and three times brighter than the brightest tidal disruption event. 

Known as AT2021 lwx, the explosion has lasted more than three years, seeing a vast contrast to a supernova which is only visible for a few months. 

According to the study, it took place nearly eight billion light years away, when the universe was around six billion years old, and is still being detected by a network of telescopes.

Astronomers discover the largest cosmic explosion ever seen

Led by the University of Southampton astronomers, the explosion is said to be a result of a vast cloud of gas, possibly thousands of times larger than our sun, that has been violently disrupted by a supermassive black hole. 

Fragments of the cloud would be swallowed up, sending shockwaves through its remnants, as well as into a large dusty “doughnut” surrounding the black hole.

These events are very rare and have never been witnessed at this size before, according to researchers. 

AT2021lwx was first detected in 2020 by the Zwicky Transient Facility in California and subsequently picked up by the Asteroid Terrestrial-impact Last Alert System (ATLAS) based in Hawaii.

Dr Philip Wiseman, research fellow at the University of Southampton, who led the research, said: “We came upon this by chance, as it was flagged by our search algorithm when we were searching for a type of supernova.

“Most supernovae and tidal disruption events only last for a couple of months before fading away. For something to be bright for two plus years was immediately very unusual.”

The team also shared that they believed it was most likely that the explosion was caused by an extremely large cloud of gas (mostly hydrogen) or dust that has come off course from its orbit around the black hole and been sent flying in.

The findings are published in Monthly Notices of the Royal Astronomical Society.