The darkest skies on Earth

In search of pristine night skies and true darkness, author Paul Bogard travelled 5,000 miles to northern Chile. What he found amazed him

- Paul Bogard

We leave La Serena at dusk, heading east towards the stars. The 90-minute drive winds through the Elqui Valley, lush green with vineyards and home to skies so dark that international observatories on Cerro Tololo and Cerro Pachon are sited here, shining on distant mountaintops silver and rose-gold in the setting sun. Our destination is a small private observatory and our goal is to stare into the Universe.

The chance to do so is the reason I've travelled to northern Chile, where clear dry air and pristine skies have made it the world's most important area for astronomy. That I would want to travel 5,000 miles just to see what every human for most of history could see by stepping away from the campfire, or by leaning out of the back door, is testament to the never-ending spread of light pollution. Even here, as cutting-edge observatories are built to see further into space than we have ever seen before, that threat is lurking. And the stakes are high; by 2030, as much as 70 per cent of the world's astronomical infrastructure will be in northern Chile.