San Pedro de Atacama Stargazing Tour with Telescopes

The Atacama Desert night sky

The Atacama Desert around San Pedro de Atacama is the driest non-polar desert in the world, at about 2,400 metres with almost no humidity, very little cloud and, outside the town, hardly any artificial light. That is why the world's largest observatories were built on the surrounding plateaus and why Atacama Desert stargazing has become one of the main reasons to visit northern Chile. On a moonless night the Milky Way is bright enough to cast a faint shadow, and the Magellanic Clouds, satellite galaxies invisible from Europe and North America, hang clearly above the horizon.

The southern hemisphere gives you a different sky from the one most visitors know. The Southern Cross, Alpha and Beta Centauri, the dense star clouds of the galactic centre in Sagittarius and the Carina Nebula are all high overhead at the right time of year. Our astronomy guide traces the constellations with a laser pointer and tells the stories the Atacameño people and the ancient Greeks attached to them before the telescopes are opened.

The observation site outside San Pedro de Atacama

After meeting in the town centre, the group drives about 15 minutes into the desert to a private observation site chosen for its open horizon and distance from the lights of San Pedro de Atacama. There are no buildings or trees to block the view, and after a few minutes your eyes adapt to the darkness and the number of visible stars multiplies. The site is set up with several telescopes, seating and blankets, so you can stay comfortable during the roughly two hours spent under the sky.

Temperatures in the desert drop sharply after sunset, even in summer, which is why warm clothing is essential and why hot drinks are served before the drive back. Because the site is close to town, the tour fits easily into an evening after a day trip to the lagoons or the salt flat, and the return van drops you back in the centre of San Pedro de Atacama at about 23:00, where most hotels are within walking distance.

Telescope viewing: planets, clusters, nebulae and galaxies

The heart of the night is the telescope session. Your guide explains how to look through the eyepiece and what you are seeing, then moves the instruments from object to object: the rings of Saturn or the cloud bands and moons of Jupiter when they are up, coloured double stars, the jewel-box clusters of the southern sky, glowing nebulae where stars are being born, and distant galaxies that appear as soft smudges of ancient light. The programme changes with the season and with what is above the horizon that night.

This is the part that makes a telescope tour in San Pedro de Atacama different from simply looking up: objects that are a blur to the naked eye resolve into structure, and the guide puts each one in context, from distances in light-years to how stars live and die. You also receive an astrophotography souvenir, a long-exposure photo of your group under the Milky Way, sent to you after the tour.

San Pedro de Atacama by night: moon phases and seasons

San Pedro de Atacama is a small oasis town of adobe streets at the foot of the Licancabur volcano, and its centre is where the shared tour begins and ends. Because the town is tiny and surrounded by desert, it takes only minutes to leave the lights behind, which is why things to do at night in San Pedro de Atacama are dominated by astronomy. The best time for a stargazing tour is the week around the new moon; the clearest months are the southern winter, from April to October, when the galactic centre is overhead.

On the nights around full moon the sky is too bright for faint objects, so a moon-and-planets tour is offered instead, concentrating the telescopes on lunar craters and the brighter planets. In the southern summer, from December to February, departures run later because of the late sunset, and occasional altiplano storms can bring cloud. If the sky is covered, the tour is moved to another night or refunded.