The VLT’s artificial star

This new image, taken by ESO Photo Ambassador Gianluca Lombardi, shows a stunning array of colours, ranging from the haze of pink dominating the bottom of the frame to the blues and whites of the Milky Way above. The blocks visible at the foreground of the image are the Unit Telescopes of the Very Large Telescope (VLT), based at ESO's Paranal Observatory in Chile.

Cutting through the scene is a harsh yellow slash. This prominent streak is the VLT's laser guide star, which is part of the telescope's adaptive optics system that compensates for the blurring effects of the atmosphere. Light from the sky is distorted as it travels through the atmosphere due to local variations. Whenever possible, astronomers hunt down a bright star to calibrate their observations, but when there is no suitable star near enough to their target, they have to rely on an artificial one — created by pointing a bright, piercing laser up into the night, as shown in this image.