Below the trails left by the stars in a dark and clear night as seen in this cool space wallpaper, a laser beam shoots out of Yepun, the fourth Unit Telescope of Europe’s flagship observatory, ESO’s Very Large Telescope (VLT). Adaptive optics is a technique that allows astronomers to overcome the blurring effect of the atmosphere and obtain images almost as sharp as would be possible if the whole telescope were placed in space, above Earth's atmosphere.

Credit: ESO/Y. Beletsky