The Event Horizon Telescope (EHT) — a planet-scale array of eight ground-based radio telescopes forged through international collaboration — was designed to capture images of a black hole. In coordinated press conferences across the globe, EHT researchers revealed that they succeeded, unveiling the first direct visual evidence of the supermassive black hole in the centre of Messier 87 and its shadow. The shadow of a black hole seen here is the closest we can come to an image of the black hole itself, a completely dark object from which light cannot escape. The black hole’s boundary — the event horizon from which the EHT takes its name — is around 2.5 times smaller than the shadow it casts and measures just under 40 billion km across. While this may sound large, this ring is only about 40 microarcseconds across — equivalent to measuring the length of a credit card on the surface of the Moon. Although the telescopes making up the EHT are not physically connected, they are able to synchronize their recorded data with atomic clocks — hydrogen masers — which precisely time their observations. These observations were collected at a wavelength of 1.3 mm during a 2017 global campaign. Each telescope of the EHT produced enormous amounts of data – roughly 350 terabytes per day – which was stored on high-performance helium-filled hard drives. These data were flown to highly specialised supercomputers — known as correlators — at the Max Planck Institute for Radio Astronomy and MIT Haystack Observatory to be combined. They were then painstakingly converted into an image using novel computational tools developed by the collaboration.

Of all the enigmatic phenomena in our universe, there’s perhaps one that has captured our attention and imagination the most, even though we had never actually seen one: the black hole. These space objects are so dense that even light cannot escape their grip.

Ever since Einstein first proposed their existence, we’ve made simulations, art, and CGI versions of what we imagine black holes could look like. But it wasn’t until this morning that we saw a black hole for the first time. We have finally gazed into the cosmic abyss.

On Wednesday morning, teams of scientists around the world who work on an experiment called the Event Horizon Telescope released a much-anticipated image of the ultramassive black hole at the centre of the M87 galaxy.

This galaxy is 55 million light-years away in the Virgo supercluster, and it is 6.5 billion times more massive than our sun. “You’re looking at a black hole that is essentially the size of our entire solar system,” says Sera Markoff, EHT team member and professor of theoretical astrophysics at the University of Amsterdam.

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