Making the shadow of black holes visible. Image, measure, and understand astrophysical black holes. These are the goals of a global effort known as the Event Horizon Telescope Collaboration. Combining radio telescopes all around the world, the collaboration succeeds in zooming into the closest neighborhood of supermassive black holes in the centers of galaxies: M87 and our own Milky Way.
The resolution of this virtual Earth-sized radio telescope exceeds the projected size of these black holes, i.e. the size of their event horizon, from which nothing can escape the enormous gravitational field, not even light. This breakthrough opens a new window into the study of black holes, their event horizons, and gravity.
The whole endeavor is largely made possible by European research and investment, starting from the very idea of observing “shadows” and demonstrating the feasibility of such observations.