But researchers have discovered one such supermassive black hole exploded with such incomprehensible power it ripped open the usually closed fields around the so-called event horizon, the edge of the black hole itself. The blast is believed to be the most destructive explosion in spacetime since the Big Bang at the creation of the universe itself.

The figures are truly mind-bending.

The hole the explosion punched into the super-hot medium known as cluster plasma around the black hole was the size of 15 Milky Ways.

The Milky Way is our own galaxy – and it’s quite big. It contains 200 BILLION stars like the Sun and if NASA’s Voyager satellite, which is currently travelling at 62,000kmh (38,000 mph), were to try and cross it the journey would take more than 1,700 MILLION years.

The hole, described as a crater in spacetime, was spotted in the Ophiuchus galaxy cluster, about 390 million light-years from Earth. It is 15 Milky Ways wide.

The incomprehensibly powerful blast was so huge researchers initially dismissed it as a mistake in measurement.

Professor Melanie Johnston-Hollitt, from the Curtin University node of the International Centre for Radio Astronomy Research, said the event was extraordinary.

She added: “We’ve seen outbursts in the centres of galaxies before but this one is really, really massive and we don’t know why it’s so big.

“But it happened very slowly—like an explosion in slow motion that took place over hundreds of millions of years.”

Lead author of the study Dr. Simona Giacintucci, from the Naval Research Laboratory in the United States, likened the blast to the 1980 eruption of Mount St. Helens, which ripped open the side of the volcano.

But she added: “The difference is that you could fit 15 Milky Way galaxies in a row into the crater this eruption punched into the cluster’s hot gas.”

Professor Johnston-Hollitt said the cavity in the cluster plasma had been seen previously with X-ray telescopes but scientists ruled out an explosion as impossible.

She said: “People were sceptical because of the size of outburst but it really is that. The Universe is a weird place.”