Two monster black holes have been discovered by scientists. The has been described by Lorena Hernández-García, an at the Millennium Institute of Astrophysics as a "very weird event".

It is the first of its kind and involves the "disruption" of a cloud of gas by the "monster" black holes in a galaxy one billion light-years away from the Cygnus constellation, on the northern edge of the .

The two voids are estimated to collectively contain 40 million times the Sun's mass and are around 16 billion miles apart, taking light one day to travel between them.

According to NASA, the black holes will collide and merge in an estimated 70,000 years.

Ms Hernández-García published a paper on the bizarre interactions between the holes and the cloud of gas on November 13. She said: "It's a very weird event, called AT 2021hdr, that keeps recurring every few months.

"We think that a gas cloud engulfed the black holes. As they orbit each other, the black holes interact with the cloud, perturbing and consuming its gas. This produces an oscillating pattern in the light from the system."

The phenomenon was first spotted by scientists in California in 2021 and was initially thought to be a supernova. Ms Hernández-García and her team began keeping an eye on the black holes in late 2022 using NASA's Swift Observatory satellite.

To narrow down the strange ultraviolet oscillations of the black holes, the team used a Goldilocks-style of elimination to rule out explanations like the destruction of a star and arrive at the truth - that a large gas cloud, bigger than the voids themselves, was being repeatedly disrupted.

NASA said the cloud was being ripped apart by gravity when it entered the black holes, creating filaments that increased in heat and density and caused some gas to be ejected in a fluctuating pattern - creating the intermittent light first seen by US astrophysicists.

Ms Hernández-García's research team is also studying the cloud of dust's home galaxy, which is in the process of merging with another one nearby. But the discovery of AT 2021hdr, which continues to be under observation, marks a step further in our understanding of the constantly-changing cosmos.

S. Bradley Cenko, Swift's principal investigator at NASA's Goddard Space Flight Centre in Maryland, said: "As Swift approaches its 20th anniversary, it's incredible to see all the new science it's still helping the community accomplish. There's still so much it has left to teach us."