The historic image, published Thursday (May 12), of what scientists call Sagittarius A* was taken by a planet-wide array of telescopes called the Event Horizon Telescope (EHT). Telescopes used the timing of the atomic clock to precisely combine their data, which is no easy task given that the material around Sagittarius A* scientists were photographing changes in shape every minute.
While the result is still not clear to non-specialists, the scientists said this was because the collaboration was at its maximum potential.
“We’re pushing our instruments to the limit here,” Michael Johnson, a member of the EHT team who is also an astrophysicist at Harvard and Smithsonian University, told reporters during a Thursday briefing. He said the image depicts “the best features you can see” because the telescope is at the diffraction limit, which is the limit of resolution.
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“To get a clearer picture, we need to move our telescopes farther…or we need to move to higher frequencies,” Johnson said, adding, “We are just at the breaking point here.”
And because the Event Horizon Telescope is already an array the size of Earth, moving its observatories apart is quite a challenge. Scientists have talked about a group of space telescopes that could one day image black holes at distances wider than Earth’s orbit. But for now, the new Sagittarius A* image sharpness is the best we can do at the moment given the amount of data involved.
Team member Catherine Bowman, a computer scientist at Caltech, added that the publicly available images also don’t reveal all the subtleties of the image’s resolution.
The original data, valued at about 3.5 petabytes (the equivalent of 100 million TikTok videos, according to EHT), had to be compressed and modified to fit standard online and cross-media public distribution channels. So much data was included that EHT investigators had to ship each other’s hard drives for scientific work, rather than stream it online.
“This photo is actually one of the most accurate I’ve ever seen,” Bowman said. “It looks blurry on the screen because we only see a few pixels, but it’s actually one of the sharpest images ever.”