From the platform of the VLT, looking east, the first hint of daylight emerges. The Milky Way arcs overhead, looking close enough to be the central beam in a vast cathedral ceiling

Credit: ESO

Sunset over the Very Large Telescope on the 2, 600-metre-high Cerro Paranal in the Atacama Desert, Chile

Credit: ESO

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EVEN WHEN YOUR brain knows you're looking at the VLT your eyes refuse to believe it. Seen from a distance, the Southern Hemisphere's largest astronomical facility, aptly named the Very Large Telescope, looks like a mirage or a sci-fi special effect - an impossibly large and elaborate structure grafted onto an equally alien-looking landscape.

In my case, the otherworldly effect is augmented by a four hour drive from the city of Calama, across some of the most barren and rugged terrain in the world.

This is a desert made of endless mountains, running north to south in three great ranges. Of these, the Cordillera de la Costa is nearest to the sea. Turning off the Pan-American Highway, we follow a side road deep into the range until another turn takes us up a steep rise.

As we round a bend, the top of Cerro Paranal, a 2,600-metre-high peak, suddenly slides into view. The mountain is sprouting four monolithic cylinders, each housing one of the European Southern Observatory's four identical 8.2-metre telescopes. The sky overhead is a brilliant blue.

Marine biologists have their coral reefs, particle physicists have the Large Hadron Collider, but when it comes to astronomy, nothing is closer to paradise than this desolate stretch of northern Chile known as the Atacama Desert.

Billed as the driest place on Earth, the region's parched climate, high altitude and extreme temperatures imposed severe constraints on the first people to settle here thousands of years ago, just as it later dismayed conquistadors in search of easy gold.

Over geologic time, the dry environment produced and preserved extensive salt deposits, along with sodium nitrate useful for fertiliser and explosives - a once-precious natural resource which, in 1879, led the Chilean government to seize the Atacama, sparking a bloody war with Bolivia and Peru.

Today, another resource - smooth-flowing, clear, dry air - is drawing astronomers to the Atacama in droves, and the invasion is ramping up. One or more of three giant optical telescopes currently in development will be situated somewhere in the region.

The world's most advanced radio observatory is already under construction here. The reason is not that the mountains of the Atacama are the highest in the world, but that they offer a steady, cloudless view of the night and are about as close to the conditions of space as you can get from the Earth's surface.

"We're observing practically all the time," says Chris Lidman, a senior astronomer at the VLT. Although the Pacific is in plain sight, a mere 12 kilometres from the summit of Paranal, the mountain paradoxically receives less than 10 mm of precipitation annually. The VLT rarely loses a night to poor weather. "It's really a special place," he says.

It is also an incredibly unlikely one. A desert mountaintop is not made for human inhabitants. To comfortably maintain over 100 observatory visitors and personnel working each day and night, the VLT requires a steady stream of materials and supplies, including food and water, all of which must be trucked in from the coastal city of Antofagasta, an hour's drive away.

Because there is nowhere nearby to stay, the observatory residence operates as a full service hotel, complete with all-night cafeteria and swimming pool. Built partly into the mountainside, the residence has an understated exterior that sets up visitors for a major surprise: coming in from a blazing hot desert afternoon, a set of heavy double doors opens onto a lush, climate-controlled atrium full of tropical plants. The setting is an immediate antidote to the desiccated extremes of the Atacama.

Its incongruous luxury also conjures up the image of an evil genius' secret lair, & agrave; la James Bond. No wonder that Hollywood came to Paranal recently to film sequences for the latest Bond flick, A Quantum of Solace. Yet the movie doesn't do justice to
the real thing.

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