The supermassive black hole at the center of our galaxy, known as Sagittarius A, is about 4 million times the size of the sun and about 27,000 light years from Earth. The images were a joint effort of 300 researchers from 80 institutions working with eight different telescopes across the globe.
Displaying the pictures for the first time during a press conference, the University of Arizona’s Dr. Feryal Özel described the image.
“This image shows a bright ring surrounding the darkness, the telltale sign of the shadow of the black hole,” she said. “Light escaping from the hot gas swirling around the black hole appears to us as the bright ring light that is too close to the black hole close enough to be swallowed by it eventually crosses its horizon and leaves behind just the dark void in the center.”
Basically – picture an orange donut with a black hole in the center. The image is also blurry. It mirrored the only other picture of a black hole taken in another galaxy. University at Albany Physics Department Chair Keith Earle says it reinforces a belief that many galaxies have a massive black hole in their center.
“One thing that one can say from the imaging that's been done is that just glancing quickly at them, you see that they look very similar, even though at least according to the experts, the kinds of black holes that they are, show some variety, but what it does suggest is that even close to a black hole, the Einsteinian theory of general relativity seems to make predictions that are backed up by observational data,” he said.
Earle there referencing the well-known E-equals-M-C-squared equation. Michael Johnson from the Harvard Smithsonian Center for Astrophysics further explains.
“The Einstein's theory of general relativity then predicts exactly what size shadow the black hole should cast. So, this theoretical feature, the shadow is the image of the Event Horizon, it's our line of sight into the black hole.”
EHT scientists called it the “strongest test of general relativity to date.” However, Earle warns there are still discrepancies.
“I think that a lot of scientists get excited when theories get broken. That means that there's a new level of understanding that we need to achieve and that can sometimes take a very long time,” he said. “So, I guess both results are interesting. In this case, we do seem to have some confirmation of the Einsteinian theory, at least at the level that we can observe, but even if we hadn't, that would also be an interesting result.”
While pop culture usually describes black holes as terrifying and swallowing everything in their path - Özel says people have nothing to worry about.
“The way black holes behave depends a little bit on the amount of material that is falling onto them,” she explained. “The one in the center of our galaxy, Sagittarius A star, is actually, as Michael mentioned, eating very little and because of that, its environment is relatively gentle.”
EHT scientists say their next goal is to capture video of the black hole. Earle explained what scientists could learn from video, rather than still photos.
“Think about images for example of classical ballet. And so, if you see production stills from a ballet concert, you just have these frozen moments in time, which can be very informative and aesthetically pleasing in themselves. But, it's only when you see the dance, that you begin to appreciate the fact that dance is a dynamic process and it’s the same thing with images of astronomical objects."
Earle also noted the significance of the image is not just scientific.
“It kind of reinforces the image that humanity is a small thing on the scale of astronomical distances and, speaking only for myself, that encourages a kind of humility that I wish were more widespread.”
