In interferometry [0], you need your telescope components to be collecting data simultaneously so that you can interfere their collected light together - so the

In interferometry [0], you need your telescope components to be collecting data simultaneously so that you can interfere their collected light together - so the maximum possible separation is about the diameter of the Earth. (The VLBA [1] and the EHT [2] make use of most of this potential.) There have been proposals to extend this maximum baseline by having space-borne interferometers (perhaps orbiting the Sun), but practically, they are a few decades away at best. [3] [0] https://en.wikipedia.org/wiki/Astronomical_interferometer https://en.wikipedia.org/wiki/Astronomical_interferometer [1] https://en.wikipedia.org/wiki/Very_Long_Baseline_Array https://en.wikipedia.org/wiki/Very_Long_Baseline_Array [2] https://en.wikipedia.org/wiki/Event_Horizon_Telescope https://en.wikipedia.org/wiki/Event_Horizon_Telescope [3] https://www.noao.edu/meetings/interferometry/workshop-files/Carpenter-Space-comp.pdf https://www.noao.edu/meetings/interferometry/workshop-files/...