Since the mid-20th century, a number of astronomical observatories have been constructed at very high altitudes, above . The largest and most notable of these is the Mauna Kea Observatory, located near the summit of a volcano in Hawaiʻi. The Chacaltaya Astrophysical Observatory in Bolivia, at , was the world's highest permanent astronomical observatory from the time of its construction during the 1940s until 2009. It has now been surpassed by the new University of Tokyo Atacama Observatory, an optical-infrared telescope on a remote mountaintop in the Atacama Desert of Chile.
Since the mid-20th century, a number of astronomical observatories have been constructed at very high altitudes, above . The largest and most notable of these is the Mauna Kea O?bservatory, located near the summit of a volcano in Hawaiʻi. The Chacaltaya Astrophysical Observatory in Bolivia at , was the world's highest permanent astronomical observatory from the time of its construction during the 1940s until 2009. It has now been surpassed by the new University of Tokyo Atacama Observatory, an optical-infrared telescope on a remote mountaintop in the Atacama Desert of Chile.