Sagittarius A*, the supermassive black hole at the center of our galaxy, has been imaged!
image by EHT Collaboration
The collaborative, Earth-spanning radio telescope imaging group, the Event Horizon Telescope, has released their composite radio image of A*, the first time the hole has been directly imaged. They say this was a harder image to get than their first-ever black hole image, the 2019 image of the supermassive black hole at the center of distant galaxy M87; for one thing, for this image they had to get readings through all the dust on the galactic plane between us and the core.
They said it exactly matched what was predicted for our black hole by Einstein's Theory of General Relativity: "it appears to us to have about the same size in the sky as a donut on the Moon," and "is about the size of the orbit of Mercury around our sun" (quote from AP News).
Speaking of the increased difficulty in imaging A*, they also said: "The gas in the vicinity of the black holes moves at the same speed — nearly as fast as light — around both Sgr A* and M87*. But where gas takes days to weeks to orbit the larger M87*, in the much smaller Sgr A* it completes an orbit in mere minutes. This means the brightness and pattern of the gas around Sgr A* was changing rapidly as the EHT Collaboration was observing it — a bit like trying to take a clear picture of a puppy quickly chasing its tail."
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(Got the pencils for the next A* page done today—painting tomorrow!)
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