> There are limits to the angular separation a telescope can detect. Even the very largest telescopes on Earth (or more often: arrays of several telescopes, eff

> There are limits to the angular separation a telescope can detect. Even the very largest telescopes on Earth (or more often: arrays of several telescopes, effectively creating multi-thousand-kilometer baselines) can resolve the disks of even the largest stars. Just to clarify: In radio-bands we can easily achieve sub-mas angular resolution using VLBI (the mentioned multi-thousand-kilometer baselines) or large arrays (ALMA, VLA, etc.) In the optical/NIR bands your baselines are typically limited to a few hundred meters, where you can go down to mas, but it's much more difficult than in the radio bands. And direct imaging of the disks of the largest stars is possible in the optical/NIR.