The telescopes you see here are 3 out of our 4 Auxiliary Telescopes. Each one has a 1.8 m mirror. These telescopes work together using a technique called interferometry: by combining their light we can achieve the resolution of a "virtual" telescope as large as the separation between the individual telescopes.
One cool thing about these Auxiliary Telescopes is that we can move them along rails! By changing the separation and orientation of these telescopes we can probe different levels of detail in the astronomical objects we study.
🎥 ESO