http://news.discovery.com/space/very-large-telescope-fires-up-awesome-laser-system.htm [quote]On April 26, Paranal saw “first light” of its Four Laser Guide Star Facility (4LGSF), the most powerful adaptive optics system on the planet. Adaptive optics are used for ground-based observatories that have to observe through a layer of atmosphere. Earth’s atmosphere can obscure our view of the universe from the ground; dynamic atmospheric processes can create turbulence and haze in the upper atmosphere. To compensate for this blurring effect, lasers are used to create artificial “guide stars” in the upper atmosphere.[/quote] [quote]In the case of the VLT’s new adaptive optics system, four 22 Watt laser beams shoot out of the dome. On encountering sodium atoms in the high atmosphere, these atoms glow, creating fake stars. These points of light at then used by the telescope to directly measure the amount of turbulence in the upper atmosphere. This information is then fed back into automated systems on the telescope to manipulate the telescope’s primary mirror, compensating for the atmospheric interference. By canceling out atmospheric interference, the observatory will get a crisper and more precise view of distant stars and galaxies.[/quote] Edit, this was in Chile BTW