ESO's Very Large Telescope (VLT) observatory was inaugurated in March 1999. It is located in the north of Chile, about 500 km south of Santiago, on the edge of the Atacama Desert, 2600 m above sea level. altitude at the top of Mount Cerro Paranal. Astronomers had the choice between this site and that of Cerro Armazones located 20 km away at 3000 m altitude but it was too windy, the domes being more subject to the effects of turbulence. Since the Pinochet government also granted ESO 795 km2 of land around the site, the Paranal site was finally chosen.

The European observatory has four identical UT1 to UT4 telescopes baptized in the Mapuche language: Antu (the Sun), Kueyen (The Moon), Melipal (The Southern Cross) and Yepun (Venus). Each telescope is equipped with a mirror of 8.20 m in diameter and 17.7 cm in thickness whose surface has been polished to an accuracy of 12 nm (P-V difference of λ/100) or about 15 atoms in thickness! This is called astronomical quality optics. The focal ratio varies between f/2 at the primary focus and f/15 at the Nasmyth focus (bent).

A VLT or Gemini class telescope is able to observe details of about 8 meters on the Moon (but this was never done, see this FAQ). On the other hand, in 2002, only one VLT was able to observe details of about 130 meters or 0.07 of arc on the Apollo 11 site, but it was still insufficient to distinguish the abandoned material on the Moon.

The latest technology is the optical interferometry of the French Antoine Labeyrie of the College de France. The principle consists in coupling with very great precision the images of several distant telescopes. Applied to VLTs, we talk about VLTI.