For the first time ever, astronomers on Wednesday unveiled the first picture of a black hole. A lopsided ring of light surrounding a dark circle.
Humanity has finally photographed the first picture of a black hole deep in the heart of the Messier 87 galaxy.
“We have seen what we thought was unseeable,” Sheperd Doeleman, of Harvard University and the Harvard-Smithsonian Center for Astrophysics, said today (April 10) during a press conference at the National Press Club in Washington, D.C.
The image looks just like an artistic rendering, but this time, it’s all real.
Doeleman directs the Event Horizon Telescope (EHT) project, which captured the epic imagery.
To capture the image, astronomers reached across intergalactic space to Messier 87, a giant galaxy in the constellation Virgo. There, a black hole, several billion solar masses, is unleashing a violent jet of energy some 5,000 light-years into space. The black hole lies some 55 million light-years away from Earth.
“It’s a distance that we could have barely imagined,” Frederic Gueth, an astronomer at France’s National Centre for Scientific Research (CNRS) and co-author of studies detailing the findings, told AFP.
Most speculation had centered on the other candidate targeted by the Event Horizon Telescope—Sagittarius A*, the black hole at the center of our own galaxy, the Milky Way. But Sag A* was too “active” to capture a clear picture, the researchers said.
By comparison, Sag A* is only 26,000 lightyears from Earth.
Capturing an image of M87’s supermassive black hole at such distance is like trying to photograph a pebble on the Moon.
Event Horizon Telescope (EHT)
The EHT is an alliance of more than 200 scientists that has been in the works for about two decades. The U.S. National Science Foundation and many other organizations in countries around the world have been funding the project for years.
The name of the project comes from the black hole’s famous point of no return. The event horizon is the boundary beyond which nothing can escape the object’s gravitational clutches.
The EHT team showed that the shape of the shadow is circular, as Einstein’s theory predicts.
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It would have been easy for the theory to come out wrong, said Avery Broderick of the Perimeter Institute for Theoretical Physics in Waterloo, Ontario: “In April 2017 this was the dog that did not bark.”
Scientists from the EHT needed two years of computer analysis of observations to unveil the image.
In all, eight radio observatories on six mountains and four continents observed the galaxy in Virgo on and off for 10 days in April 2017.
This is all an international effort.
“Instead of constructing a giant telescope that would collapse under its own weight, we combined many observatories,” Michael Bremer, an astronomer at the Institute for Millimetric Radio Astronomy (IRAM) in Grenoble, told AFP.
Knit together “like fragments of a giant mirror,” in Bremer’s words, they formed a virtual observatory some 12,000 kilometers across—roughly the diameter of Earth.
“For everything to work, we needed to have clear visibility at every [telescope] location worldwide”, said IRAM scientist Pablo Torne, recalling collective tension, fatigue and, finally, relief.
“The telescope is not looking at the black hole per se, but the material it has captured,” a luminous disk of white-hot gas and plasma known as an accretion disk, said McNamara, who was not part of the team.
“The light from behind the black hole gets bent like a lens.”
Petabytes of Data
There are good reasons why it’s taken two years for the project’s first result to come out. For one thing, each night of observing generated about 1 petabyte of data, resulting in such a haul that the team has to move its information from place to place the old-fashioned way.
“There’s no way that we can transfer this data through the internet,” EHT project scientist Dimitrios Psaltis, an astronomy professor at the University of Arizona, said at the SXSW event. “So, what we actually do is, we take our hard drives and we FedEx them from place to place. This is much faster than any cable that you can ever find.”
This slows and complicates analysis, of course. Data from the EHT scope near the South Pole, for example, couldn’t get off Antarctica until December 2017, when it was warm enough for planes to go in and out, Marrone said.
It would take another year, however, to piece together the data into an image.
“To be absolutely sure, we did the work four times with four different teams,” said Gueth.
Such ground-breaking achievement is indeed vital to the scientific process.
Thumbnail image: The first image of a black hole, from the galaxy Messier 87. Credit: Event Horizon Telescope Collaboration, via National Science Foundation