4 Laser Guide Star Facility in action

ESO's Very Large Telescope (VLT) uses state-of-the-art technology to provide the sharpest possible images. When light travels through the Earth's atmosphere it is distorted and the telescope sees a blurry image. To counteract for this effect, the VLT points an artificial laser into the upper atmosphere of the Earth to help correct for the atmospheric distortion of light. This laser is called a "Laser Guide Star". Read more about it here.