Humanity gazes into the abyss to get its first glimpse of a black hole

Sadly, USS Cygnus still missing

Black Hole
The Black hole at the centre of Messier 87 (credit: Event Horizon Telescope collaboration et al.)

Boffins have battled cries of "but it looks like an onion ring" to show off the first direct visual evidence of a supermassive black hole and its shadow.

The shadow bit is important, since imaging a black hole directly is somewhat tricky: everything gets pulled into the thing, even light.

Scientists running the Event Horizon Telescope (EHT), an array of eight ground-based radio telescopes around the world, captured the image. The black hole in question is 55 million light years from Earth and has a mass 6.5 billion times that of the Sun. It lurks at the centre of Messier 87, a massive galaxy in the Virgo galaxy cluster.

Black holes are bizarre things, having enormous mass while remaining very compact. It is theorised that one in a bright region will create something akin to a shadow due to the gravitational bending and capture of light by the event horizon.

Chair of the EHT Science Council Heino Falcke of Radboud University, the Netherlands, explained that the shadow "reveals a lot about the nature of these fascinating objects and allowed us to measure the enormous mass of M87's black hole."

Multiple imaging methods have shown a ring-like structure with the shadow in the centre.

The shadow itself was predicted by Einstein's theory of general relativity and, according to Falcke, is something "we've never seen before".

The joy of getting the image and measurements is that scientists can now verify their models. Paul T P Ho, EHT board member and director of the East Asian Observatory commented: "Many of the features of the observed image match our theoretical understanding surprisingly well." Hence the confidence in the mass measurements.

National Science Foundation (NSF) director France Córdova described the snap as "a huge day in astrophysics". As well she might, while the achievement is undeniable, as the largest contributor to the EHT project, the NSF has poured in $28m over the last two decades. Rather like a black hole for dollar bills.

However, in this case, the EHT has successfully spat out imagery of one of the mysterious things.

The EHT represents some mindboggling science, using the rotation of Earth to combine the eight facilities into one giant Earth-sized telescope observing at a wavelength of 1.3mm. The very-long-baseline interferometry (VLBI) used allows the EHT to get to an angular resolution of 20 micro-seconds, "enough to read a newspaper in New York from a sidewalk café in Paris" according to the NSF.

While we were put in mind of an onion ring by the image, or perhaps a slightly ropey special effect from an early take on the Eye of Sauron, wags on Twitter were quick to suggest something else.

Something, we like to think, represents the hands of international co-operation reaching out, over the event horizon.

Or something like that. ®

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