And that kind of black hole may be the standard. That’s not the case for Sgr A*, which is a much more quiet kind of black hole. The gravitational pull of some black holes, like the one in the middle of M87, can actually speed up the surrounding plasma, causing the material to shoot outward as jets of light. Sgr A* also doesn’t convert much of its gravitational energy into light. “If Sgr A* were a person it would consume a single grain of rice every million years,” Johnson said. Only a small portion of the material surrounding the object actually makes it inside. For one thing, they’ve determined that Sgr A* isn’t a particularly hungry black hole. Sgr A* is exciting because it’s common.”īut, with this fuzzy image, the scientists have already learned a lot. “M87 was exciting because it was extraordinary.
“That means as we were collecting data during the Earth’s rotation, the material was swirling around Sgr A* so quickly that Sgr A*’s appearance could change from minute to minute,” Bouman said. The material that swirls around Sgr A* close to the event horizon - the point of no return for the particles falling into the black hole - moves so incredibly fast that the object appears to change in real time. While it makes for an interesting light show, it changes the composition of the black hole every few hours, making it tricky to observe over time. On top of that, the material that does surround Sgr A* exhibits weird flaring when the particles surrounding the black hole are accelerated to much higher energies. Though it’s closer to Earth than M87’s black hole, Sgr A* is smaller and less active, and the material surrounding the object is much dimmer, making it harder to observe. Image: National Science Foundation/Keyi “Onyx” Li “Taking a picture with the EHT is like listening to a song being played on a piano that has a lot of missing keys,” Katie Bouman, an astronomer at Caltech, said during the press conference. At the same time, EHT also observed Sagittarius A*, but crafting its image proved to be much more challenging and time-consuming. It’s then up to the EHT scientists to piece together the data the telescopes gathered to create a single image.ĮHT used the same technique to capture M87 eight EHT radio dishes spent a week observing that black hole in April 2017, which then resulted in months and months of work to compile the data into the image that was eventually released. The radio telescopes all work together to observe the same object, behaving as if they are one giant planet-sized telescope. The EHT is a wide-ranging array of radio dishes spread out across five different continents. Since building such an apparatus isn’t exactly realistic, scientists came up with a workaround. To capture an image like this of Sagittarius A*, a single telescope would have to be the size of planet Earth to get the job done, according to the Event Horizon Telescope group. Snapping pictures of these black hole shadows is no simple task, though. Snapping pictures of these black hole shadows is no simple task What EHT is actually capturing is the black hole’s shadow against the backdrop of that glowing gas and dust. If a supermassive black hole is surrounded by a swirling disc of gas and dust, that material will glow bright since the gas and dust is sped up and heated by the powerful gravitational pull of the nearby hole.
Instead, we can capture the silhouette of a black hole.
Black holes, by their very nature, can’t be “seen,” as these objects are so massive that nothing can escape their gravitational pull - including light. Truthfully, one cannot capture an image of a black hole directly. “So it’s a very active area of research.” Distance comparison of M87 and Sgr A*. “These supermassive black holes, we don’t really know how they formed or grew so large,” Meredith Clark Powell, a black hole researcher at Stanford University, tells The Verge. With each new supermassive black hole picture we get, scientists learn a little bit more about these enigmatic objects. She added, “This image shows a bright ring surrounding the darkness - the telltale sign of the shadow of the black hole.” “Until now, we didn’t have the direct picture confirming that Sgr A* was indeed a black hole,” Feryal Özel, an astronomer at the University of Arizona and member of EHT, said during a press conference announcing the news. But this is the first time we have a direct image of its dark central area, or “shadow,” even more proof of life of the nexus of our cosmic neighborhood. Scientists have inferred its existence at the center of our galaxy for decades based on how objects move around the black hole. Located 26,000 light-years from Earth, Sagittarius A*, or Sgr A*, is thought to be roughly 4 million times the mass of our Sun. Now, the team is back with another photo of a black hole, this one right in our own backyard.
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