On Wednesday, an international coalition of astronomers announced that they had seen the unseeable and were ready to share it with the world. For the first time in human history, the public was invited to gaze into a black hole spinning in a galaxy 55 million light years away from Earth.
At a news conference unveiling the highly anticipated image, Shep Doeleman, a Harvard astrophysicist who directed the project, declared, “We have seen what we thought was unseeable.” His audience reacted with cheers, gasps, and applause as the screen revealed a majestic image of a dark hole surrounded by vivid orange and yellow bands.
Black holes are mysterious objects that have captured the imagination of astronomers for decades. Though the name implies emptiness, a black hole is actually a region of extremely compact matter. The gravitational pull of this region becomes so intense that it deforms the fabric of space itself, pulling everything into its center–even light.
This absence of light makes black holes notoriously difficult to capture. As any astronomy student can attest, depictions of black holes have traditionally been limited to textbook illustrations and digital simulations. But what was once speculation has now been made real.
The historic image originates from the Event Horizon Telescope, which is not one device, but a network of radio observatories spanning eight facilities on four continents. In 2017, observatories in Antartica, South America, North America, and Europe created a giant telescope the size of Earth itself. Continuity was key; locations were carefully synchronized via atomic clocks, focusing on specified points of study for intermittent periods over a 10-day span.
The Event Horizon Telescope observed an immense galaxy in the constellation Virgo called Messier 87, also knows as M87. This is where the gigantic black hole in the celebrated image lies. The telescope also observed a second black hole within our own Milky Way Galaxy.
Event Horizon returned a colossal amount of data too large to be transmitted via the internet. As a result, one of the most advanced technological achievements in recent human history was stored and transferred on a cache of floppy disks. The Event Horizon team has spent the past two years examining this information at two locations. The team chose to prioritize M87’s black hole because Sagittarius A *, the black hole inside our galaxy, contains gases that swirl relatively quickly, making a clear image capture more challenging. However, the team has stated that exploring data for Sagittarius A * is the next step.
Astronomers stand to discover a great deal from the Event Horizon image. For starters, it confirms that Einstein was correct in his theory that black holes are circular in shape, though it remains to be seen how learning more about black holes will impact the theory of general relativity. Too, scientists have learned that the Virgo black hole has more mass than originally predicted. This image will also help us to better understand the laws of gravity. However, there is still much to learn about black holes. Astronomers have yet to determine how they originate or what happens to the vast amounts of matter they consume.
Though the vivid rings of light surrounding the image’s black center may seem to represent the the hole’s boundary, this isn’t the case. This area is actually called the photon orbit, a region of intense light heading towards the point of no return further inside the black hole. The gases of the photon orbit are rotating clockwise at temperatures measuring billions of degrees.
The term given to the actual edge of a black hole is “event horizon,” a horizon beyond which we cannot see. The Event Horizon Telescope takes it name from this place of no return. With the very first image of a black hole mesmerizing people across the globe this week, it seems that humanity has indeed peered further than ever before into this dark abyss of the unknown. There is no turning back.