The Atacama is so dry that its core may have gone from 1570 to 1971 without a single significant rainfall, and some of its weather stations have never recorded rain at all. It stretches across a high plateau in northern Chile, walled off from ocean moisture on both sides, and it is the driest nonpolar desert on Earth. That thin, bone-dry air holds almost no water vapour and scatters almost no light, which gives the Atacama some of the clearest skies on the planet. The world's great observatories cluster here as a result: the 66 antennas of ALMA on the 5,000-metre Chajnantor plateau, the Very Large Telescope on Cerro Paranal. The ground is nearly as strange as the sky — parts of it are so sterile that scientists come here to rehearse looking for life on other planets.
Days here feel like travelling across other worlds. Before dawn you cross the altiplano to El Tatio, at 4,320 metres the largest geyser field in the southern hemisphere, where some 80 geysers fire columns of steam into the freezing air. The Salar de Atacama itself is a crust of rough grey salt rather than a clean white pan, and its southern end is worked for lithium brine. But the desert saves its signature for night: in air this dark, the Milky Way burns bright enough to throw a faint shadow at your feet, and Saturn's rings hang sharp in a small telescope. San Pedro de Atacama, an adobe village at 2,400 metres, is the base for all of it.