January 2012 — The VLT in action
The VLT during observations. In this picture, the four 8.2-metre Unit Telescopes (UTs) are visible, named from left to right, Antu, Kueyen, Melipal and Yepun. In front of the UTs are the four 1.8-metre Auxiliary Telescopes (ATs), entirely dedicated to interferometry. A reddish laser beam is being launched from UT4 (Yepun) to create an artificial star at an altitude of 90 kilometres in the Earth's mesosphere. This laser guide star is part of the adaptive optics system, which allows astronomers to remove the effects of atmospheric turbulence, producing images almost as sharp as if the telescope were in space.