Collaboration, founded 2009
Event Horizon Telescope (EHT) Collaboration
The Event Horizon Telescope links radio dishes worldwide into an Earth-sized telescope. It imaged black holes M87* (2019) and Sagittarius A* (2022).
- Location
- Global VLBI network of radio telescopes
- Focus
- Black holes, Galaxies, Telescopes and missions
No single site
Global VLBI network of radio telescopes
The Event Horizon Telescope (EHT) is a collaboration that links radio dishes around the world into a single virtual telescope the size of Earth, a technique called very-long-baseline interferometry (VLBI). Observing at a wavelength of 1.3 millimeters, it reaches a theoretical resolution of about 25 microarcseconds, sharp enough to see the shadow of a black hole’s event horizon in a nearby galaxy. The collaboration has more than 300 members from 60 institutions in over 20 countries and regions, including the Center for Astrophysics | Harvard & Smithsonian.
Flagship instruments
- A global array of radio dishes: eight telescopes took part in the 2017 campaign behind the first images.
- 1.3-millimeter observing band: short radio waves plus intercontinental baselines give the array its resolution of about 25 microarcseconds.
Recent results
On April 10, 2019, the EHT published the first image of a black hole: a bright ring 42 microarcseconds across around M87*, a black hole about 6.5 billion times the Sun’s mass, 55 million light-years away. A polarized-light image of M87* followed in March 2021, tracing magnetic fields near the horizon. On May 12, 2022, came the first image of Sagittarius A*, our own galaxy’s black hole, matching the mass of about 4 million Suns measured from stellar orbits. A polarized image of Sagittarius A* was released on March 27, 2024.
What to watch, 2026-2030
Our sources list no dated EHT milestones for 2026-2030. A complementary test is underway at the Very Large Telescope: the team tracking the star S301 hopes to measure Sagittarius A*‘s spin directly within about 10 years (details).
Why scientists are converging here
Black holes have become laboratories. The EHT tests general relativity at the edge of the horizon, while gravitational-wave detectors test it in collisions: in 2025 the loudest merger signal yet confirmed Hawking’s area theorem. Combining images, orbits and waves is now the main way to study black holes and the galaxies that host them.