Cerro Paranal is a mountain in the Atacama desert of northern Chile that is home to the Paranal Observatory. It is the site of the Very Large Telescope (VLT) and is located 120 kilometers (75 miles) south of Antofagasta, 15 kilometers (9.3 miles) inland. The Very Large Telescope array (VLT) is the flagship facility for European ground-based astronomy at the beginning of the third Millennium. It is the world’s most advanced optical instrument, consisting of four Unit Telescopes with main mirrors of 8.2m diameter and four movable 1.8m diameter Auxiliary Telescopes. The telescopes can work together, to form a giant "interferometer", the ESO Very Large Telescope Interferometer, allowing astronomers to see details up to 25 times finer than with the individual telescopes. The light beams are combined in the VLTI using a complex system of mirrors in underground tunnels where the light paths must be kept equal to distances less than 1/1000 mm over a hundred meters. With this kind of precision the VLTI can reconstruct images with an angular resolution of milliarcseconds, equivalent to distinguishing the two headlights of a car at the distance of the Moon. The 8.2m diameter Unit Telescopes can also be used individually. With one such telescope, images of celestial objects as faint as magnitude 30 can be obtained in a one-hour exposure. This corresponds to seeing objects that are four billion times fainter than what can be seen with the unaided eye. The large telescopes are named Antu, Kueyen, Melipal and Yepun after the meaningful names of celestial objects in the Mapuche language. More… Please also visit the ESO Ultra HD Expedition blog by my friends Babak Tafreshi and Christoph Malin.