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JANUARY/FEBRUARY 2020. DISCOVER 9

Humanity’s

First Look at a

Black Hole

BY KOREY HAYNES

i

This spring, astronomers revealed the first

image ever taken of a black hole, bringing a

decades-long effort to a dramatic conclusion.

The image offers humanity its first glimpse of the

gas and debris that swirl around the object’s event

horizon, the point beyond which material disap-

pears forever. A staple of science fiction has finally

become visibly real.

“We are delighted to be able to report to you

today that we have seen what we thought was

unseeable,” said Event Horizon Telescope (EHT)

founding director Shep Doeleman when he

announced the finding in April. The team of scien-

tists made their announcement simultaneously in

seven different countries, accompanied by a series

of scientific papers published at the same time in

The Astrophysical Journal Letters.

The subject of the photo session was a nearby

galaxy, dubbed M87, and its supermassive black

hole, which packs the mass of 6.5 billion suns.

Despite its size, the black hole is so far from Earth

— 55 million light-years — that capturing the

image required a telescope the size of our planet.

The EHT fit the bill, with its network of nearly a

dozen independent observatories across the globe,

cooperating as one enormous detector. (Just eight

observatories were part of the EHT in 2017, when

researchers first gathered the image data.) The sci-

entists then spent two years analyzing and format-

ting it before they could unveil the finished picture.

A photo of a black hole, at first, seems impos-

sible. The objects are so massive and dense that

not even light can escape their pull. That means a

black hole is literally black — it neither gives off nor

reflects any light. And, sure enough, at the center of

the EHT’s image is the dark blob of the black hole

itself, which astronomers often call its shadow. But

the photo shows more than that: Surrounding the

shadow is a bright, fiery ring of light.

Feryal Özel is an astrophysicist at the University

of Arizona and an EHT collaborator. She says that

the light comes from hot gas swirling nearby,

heated up during its violent descent into the black

hole. “Our telescopes are able to pick up the light

1

s

at a

The first image of
a black hole: the
picture worth a
thousand words
— plus two years
of crunching
massive amounts
of data.