Until 2019, no one had ever actually seen a black hole. We knew they had to exist - we could watch their effects on nearby stars and gas - but no telescope had ever resolved one well enough to take a real picture. The problem was simple: black holes are tiny compared to the distances involved. Even a giant black hole looks vanishingly small from millions of light-years away.
To solve it, scientists turned the entire planet into a single, gigantic telescope. They linked eight radio telescopes scattered across Earth - from Hawaii to Spain to the South Pole - and combined their signals through a technique called interferometry. The result was effectively one telescope as wide as Earth itself.
In April 2019, the team released the first-ever photo of a black hole: a glowing orange ring around a perfectly dark circle, in the heart of a galaxy called M87. The bright ring is gas heated to extreme temperatures as it spirals in. The dark hole at the center is the event horizon. Three years later, the same team released a second image - this one of Sgr A* at the heart of our own Milky Way.
