Astronomy
Using Radio Interferometry to Image Black Hole Event Horizons
Quick fact
To resolve the event horizon of M87's black hole, we needed a telescope the size of Earth—achieved by linking radio dishes across the globe, creating a virtual instrument with 10,000 times the resolution of the Hubble Space Telescope.
Why this is interesting
Black holes swallow all light, so they are literally invisible—yet in 2019, we saw one for the first time. How can humanity capture an image of something that emits no light?