A 20W 589nm laser in action at the ESO's Allgäu Public Observatory in Ottobeuren, Germany. The yellow-orange laser makes the sodium atoms in a layer 90km high glow, creating an artificial "star" that can be observed by a telescope. The adaptive optics equipment can then use measurements of the artificial star to correct for the blurring effect of the atmosphere in the observations. Photo: ESO/T. Kasper (AVSO). |
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