The Very Large Telescope (VLT) at ESO’s Cerro Paranal observing site. Located in the Atacama Desert of Chile, the site is over 2600 metres above sea level, providing incredibly dry, dark viewing conditions. The VLT is the world’s most advanced optical instrument, consisting of four Unit Telescopes with main mirrors 8.2-m in diameter and four movable 1.8-m diameter Auxiliary Telescopes. The telescopes can work together, in groups of two or three, to form a giant interferometer, allowing astronomers to see details up to 25 times finer than with the individual telescopes.