A drop of rain is hardly news in most of the world. But in the Atacama Desert of northern Chile, it’s about as rare as the Detroit Lions reaching the Super Bowl. On average, the Atacama’s hyper-arid core, wedged between the Chilean Coast Range and the towering Andes Mountains, gets around 15 millimeters (0.59 inches) of rain per year—far less than even Death Valley, the driest place in the United States. One Atacama weather station purportedly recorded just 0.5 millimeters (0.02 inches) of rain per year from 1964 to 2001. At that rate, it would take well over a century to fill a coffee mug. Though it is technically wetter than stretches of Antarctica , the Atacama Desert is often called the driest place on Earth. It’s certainly the driest place where people live, with a history of human habitation going back thousands of years.…