Mauna Kea Observatories, Hawaii

A busy cluster of observatories, operated by several organizations, atop Mauna Kea, a 13,796-foot mountain on the Big Island of Hawaii, that is also the highest mountain in the state. Said to be the largest astronomical observatory in the world, Mauna Kea is home to the Keck telescopes, which feature two separate 10-meters in diameter mirrors, weighing 300 tons each. Together, the twin telescopes are the largest in the world, providing the greatest optical clarity and detail currently available. Also on Mauna Kea are Caltech's Submillimeter Observatory and the competing James Clerk Maxwell submillimeter telescope, which is operated by an international consortium. An antenna for the Very Long Baseline Array is on the mountain, as are several other infrared, optical, and radio observatories.