Laser to the stars

Unit telescope 4 (Yepun) of ESO's Very Large Telescope sends up laser light to create an artificial guide star. The guide star is part of the state-of-the-art Adaptive Optics technology that corrects the blurring effects of Earth's atmosphere to produce sharper images. The three other unit telescopes are also pictured, from left to right: Antu, Kueyen and Melipal.