Images: Observatories at the top of the world

A dormant volcano in the Hawaiian islands called Mauna Kea is the unlikely home of the most important collection of astronomical observatories in the world. At least it might seem unlikely: the big island of Hawaii is better known for cattle ranches, macadamia nuts and black sand beaches. But because the Mauna Kea summit, at 13,796 feet, is so high in the atmosphere, because it's far from light pollution, and because it's usually free of clouds, it's the best place on the planet for atmospheric and astronomical observations.

Mauna Kea is above the tree line, with rocky soil that looks more like a moonscape than anything you'd expect on a Pacific island not that far from the equator. The summit is accessible only via a treacherous gravel road built for four-wheel drive vehicles that snakes through the cloud layer and may be covered with snow in the winter (a visitors center is a few thousand feet below on a paved road). Observatory workers typically live in towns at sea level or in temporary quarters near the visitors center, not on the bare and lonesome summit itself.

In this photograph, from the left are the Caltech Submillimeter Observatory, the James Clerk Maxwell Telescope, and the Submillimeter Array, which includes eight 6-meter submillimeter antennas operated by the Smithsonian Astrophysical Observatory and Taiwan.

Captions by Declan McCullagh and Andy Smith