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Black hole 33 billion times the size of the sun
Courtesy of ESA/Hubble/Digitized Sky Survey

Scientists spot a black hole 33 billion times bigger than the sun

The ‘ultramassive’ black hole discovery has big implications for our future understanding of space

The enormity of space, and the objects floating around in it, can be a terrifying prospect. While we can all agree that the Earth is pretty big in human terms, even our nearest star (AKA the sun) is more than 100 times wider – even the holes that recently opened up on its surface measure between 20 and 30 times the size of our home planet. Up against some of the other cosmic objects that scientists have discovered, though, even the sun appears minuscule (a fact we should all be grateful for, since otherwise we’d be sizzled to a crisp).

Case in point: an “ultramassive” black hole that was recently discovered by a team of Durham astronomers. When they say “ultramassive”, they mean it. According to a paper published in the journal Monthly Notices of the Royal Astronomical Society, we’re talking more than 30 billion times the size of the sun. That is, quite frankly, too big for our puny human brains to truly comprehend.

In fact, at around 33 billion times the mass of the sun, the black hole is one of the biggest ever found by astronomers. According to Dr James Nightingale, the lead author of the report and a researcher in the physics department at the University of Durham, it’s actually on the “upper limit” of how large we believe black holes can theoretically become (between 10 and 40 billion times the mass of the sun). This, he says, makes it an “extremely exciting discovery”.

What are black holes, exactly? Well, they’re essentially places in space – often the result of a collapsed star – that produce so much gravity that even light can’t escape their clutches. It’s thought that every large galaxy has a supermassive black hole at its centre. But ironically, given their size, they’re very difficult to spot. The first actual image to be produced came in 2019, allowing us to view a black hole 6.5 billion times the mass of the sun by looking at the hot, bright disk of material that surrounded it.

For the first time, this most recent ultramassive black hole was spotted using a phenomenon called gravitational lensing. Essentially, scientists observed how the black hole’s extreme gravitational pull bent light from a nearby galaxy – kind of like a magnifying glass – as it warped surrounding spacetime. Confirming the size also involved using supercomputer simulations and images captured by the Hubble Space Telescope.

“Most of the biggest black holes that we know about are in an active state, where matter pulled in close to the black hole heats up and releases energy in the form of light, X-rays, and other radiation,” says Dr Nightingale. Gravitational lensing, however, makes it possible to locate and study “inactive” black holes in distant galaxies, which was previously impossible. It’s a tantalising possibility, he adds. “This approach could let us detect many more black holes beyond our local universe and reveal how these exotic objects evolved further back in cosmic time.”