In 2019, the scientists revealed M87, an even larger black hole at the center of the Virgo Galaxy cluster. This is the second time the team has obtained direct evidence of the existence of a black hole. “The result is a milestone in our understanding of black holes in general and the one at the center of our galaxy in particular.” A comparison of the images of the M87 black hole (L) and the Sgr A* black hole (R) (Credit: EHT Collaboration) “It is notoriously difficult to reconstruct images from a widely dispersed array like the EHT, and both rigor and ingenuity have been required to properly understand and quantify uncertainties,” says Colin Lonsdale, director of MIT’s Haystack Observatory. The data, stored on physical hard drives, was transported to a central location where it was 'stitched' together by a supercomputer to form the image of the black hole's shadow. The observatories, located in Hawaii, Arizona, Chile, Mexico, Spain, and Antarctica, individually captured the black hole's radio signals over four nights in April 2017, when the weather was optimal in all six regions. The black hole was imaged using the Event Horizon Telescope (EHT) - a network of eight powerful ground-based telescopes linked to form a radio array as wide as the Earth. It is believed to have a mass of about 4 million times that of our Sun. Sgr A* lies about 27,000 light-years away.

Picture of black hole