For the first time, humanity has stared into the dark heart of unfathomable chaos at the center of the Milky Way and brought its shadowy form into focus. The object staring back at us, Sagittarius A*, is a monstrous black hole that binds our home galaxy together.
On Thursday, scientists with the Event Horizon Telescope (EHT) Collaboration revealed the first direct visual evidence of Sagittarius A*, or Sgr A*, in coordinated worldwide press conferences. Composed of over 300 researchers, the collaboration made headlines three years ago for unveiling the first image of any black hole and has been attempting to image Sgr A* since 2009.
Today, the world bears witness to the fruits of their labor. And it’s every bit as groundbreaking as expected.
This dazzling light, swirling orange around a shadowy circle, traveled more than 26,000 years to reach us. It is of luminescence birthed at the edge of Sgr A* when Earth’s northern ice sheets reached as far as Manhattan, cave bears still roamed Europe and Homo sapiens settlements were being built from mammoth bones.
“I wish I could tell you that the second time is as good as the first, when imaging black holes. But that wouldn’t be true. It is actually better,” said Feryal Özel, an astrophysicist at the University of Arizona and part of the EHT Collaboration.
Özel’s sentiment comes from the fact that EHT’s image of SgrA* isn’t just a spectacular sight. It’s concrete proof that humanity has, in fact, managed to take pictures of the elusive engines powering our universe. SgrA* has a doughnut-like structure akin to the team’s previous black hole picture, therefore confirming these glowing rings aren’t the product of coincidence or environmental noise.
They represent black holes.
The saga of Sagittarius A*
It was 1974 when astronomers initially discovered evidence of Sgr A*, thanks to a very bright radio signal emanating from the heart of the Milky Way. But at the time, it wasn’t clear whether the cue came from a black hole. It was only suspected.
Over the next four decades, however, further observations revealed stars circling the radio source in extreme orbits and at extreme speed — both expected to occur around black holes. And by 2018, there was even more comprehensive confirmation that Sgr A* is absolutely a supermassive black hole, and one with a mass of over 4 million suns. Two of the scientists who studied Sgr A* were awarded the 2020 Nobel Prize in Physics.
Yet we still couldn’t actually see the black hole. Until now, that is.
An image of the Milky Way’s heart, taken by NASA’s Hubble Space Telescope in 2016.
The EHT’s incredible image is the long-sought visual confirmation of Sgr A*’s true nature, allowing us to finally lay eyes on the motor behind the Milky Way’s swirls and refining our capability to study the universe’s colossal chasms and their exotic physics. “This is a big — no, it is a huge — moment for everyone in the Event Horizon Telescope Collaboration,” said J. Anton Zensus, director at the Max-Planck-Institute for Radio Astronomy in Germany.
A detailed outline of the findings were published Thursday in a series of papers appearing in the journal The Astrophysical Journal Letters.
Image of the invisible
The gravitational effects of a black hole are so mighty the chasm basically punches a hole in spacetime. But black holes aren’t exactly “black holes.” They’re more like unseeable rifts in the cosmos.
Basically, when a big enough star dies, it collapses to a single point with an immense gravitational pull called a singularity. This pull is so unimaginably strong that when gas, dust or light falls in, the particles can never escape. Nothing can escape, which makes black holes practically invisible.
In fact, since black holes were first theorized by Einstein in the early 20th century, astronomers were only convinced these voids existed because…
Read More: Astronomers Reveal First ‘Groundbreaking’ Image of Milky Way’s Black Hole
