Guide lasers over Mauna Kea observatories, all-sky (full dome) view. The lasers emerging from the twin Keck telescopes (bottom) are used to create artificial guide stars for calibration to remove the effects of the atmosphere on observations (adaptive optics, AO). The Subaru Telescope is at top. Located near the summit (4205 metres) of Mauna Kea volcano on the Big Island of Hawaii, this collection of telescopes is one of the world's leading astronomical research facilities. Hawaii's mid-Pacific location and the high elevation provide excellent viewing conditions. The Moon (at lower right of the lasers), appears above the morning twilight.