Lasers and the Milky Way

The Milky Way rises in the sky over the Very Large Telescope in Chile, while the 4 Laser Guide Star Facility (4LGSF) does its work. The 4LGSF sends four laser beams into the skies to produce four artificial stars by exciting sodium atoms located in the atmosphere at an altitude of 90 kilometres. These stars act as reference points to artificially remove the twinkling of stars.