Radio telescopes on the Moon could image dozens of black hole shadows.

An arXiv study models Earth–Moon very long baseline interferometry and finds that placing radio dishes at five lunar sites could, under favorable geometry, let an Earth–Moon array resolve nearly 30 additional supermassive black hole shadows at sub-microarcsecond scales.

Researchers describe how adding radio dishes on the Moon could create an Earth–Moon virtual telescope with much higher angular resolution. Radio wavelengths are long, so large baselines are needed for fine detail; the Event Horizon Telescope used an Earth-sized array to image M87* and Sgr A*. The new arXiv study models placing dishes at five lunar sites—two on the far side, two on the near side, and one at the south pole—to keep targets observable as the Moon orbits. The paper evaluates how the Earth–Moon geometry affects resolution and which nearby black holes could be seen. Key points: - M87* and Sgr A* have apparent sizes near 40 microarcseconds; the Event Horizon Telescope reached roughly 20 microarcsecond resolution, with possible improvements toward about 10 microarcseconds. - An Earth–Moon baseline can, when geometry is favorable, achieve sub-microarcsecond resolution (below 1 microarcsecond), potentially resolving much smaller apparent shadows. - The study examines five lunar locations and reports nearly 30 additional supermassive black hole shadows could be observed, from the Andromeda black hole to Cyg A*, which the article reports is at the heart of a radio galaxy 760 light-years away. - Sensitivity depends on lunar dish size; assuming sensitivity comparable to current Earth observatories, resolution becomes the main limiting factor. - Building and operating lunar radio observatories faces substantial engineering and logistical challenges and is expected to be decades away. Summary: If deployed, an Earth–Moon very long baseline interferometry network would expand the set of supermassive black holes whose shadows can be imaged and could reveal finer structural detail in favorable orientations. The study identifies nearly 30 candidate targets and evaluates site geometry and expected resolution. Practical implementation will require major engineering work and long-term planning. Deployment timing and specific next steps are uncertain.