On May 12, 2022, the Event Horizon Telescope (EHT) published a direct observation of the black hole in Sagittarius A* (Sagittarius A*, referred to as "Sgr A*"), which is the first photo taken by humans. (In the following content of the article, "Sgr A*" refers to the Sgr A* black hole photographed by EHT, and "M87" refers to the M87 black hole photographed) The photo looks like a "winter shot",
it only has the quality of "360p", and it is not as shocking as "M87 - the first black hole photo in history", but it cannot hide its brilliance. Many people industry email list wondered or complained why the black hole could not be photographed more clearly, and even resulted in countless memes. To discuss this, we must first explore the following questions: Why can you "see" a black hole? A black hole is a special kind of star.
According to the predictions of general relativity and our understanding of stellar evolution, when a sufficiently massive star "ages", it collapses into an extremely small space, giving it an extremely large gravitational force. Gravity will prevent everything, including light, from escaping the black hole's event horizon, attracting countless matter and orbiting it, fo