Can you see the Milky Way from the Atacama Desert?
Quick answer
Yes, and better than almost anywhere on Earth. From this latitude the galactic core passes close to overhead instead of sitting low on the horizon, and the air holds so little water vapour that it reads as a structure rather than a haze. One thing ruins it: a full moon.
The Milky Way is visible from any properly dark site, but what you see from 23 degrees south in the driest desert on the planet is different in kind rather than in degree. The dense, dusty centre of our galaxy — the part with the visible dark lanes running through it — passes high overhead here, while from most of Europe and North America it barely clears the southern horizon through the thickest part of the atmosphere.
Why it looks different from here
Two reasons. Latitude: the galactic core culminates near the zenith rather than low in the south, so you are looking through far less atmosphere at it. And dryness: relative humidity between 13 and 38 per cent means almost nothing scattering the light on its way to you.
The best months
The galactic core is above the horizon at night from roughly March to October, with the best hours in the southern winter — June, July and August — when it is high in the middle of the night. That coincides with the driest, most stable air of the year, at 14 to 20 per cent humidity.
What will ruin it
The moon, and nothing else. A full moon scatters enough light to erase the Milky Way completely, and no telescope, guide or camera fixes it. Tours run anyway and nobody will warn you. Check your dates against the new and full moons before you book.
What else you get from this latitude
The Large and Small Magellanic Clouds, two satellite galaxies visible to the naked eye and not visible at all from most of the northern hemisphere. The Coalsack, a dark nebula silhouetted against the galaxy. The Southern Cross, and Alpha Centauri, the nearest star system to our own.
Photographing it
Your phone will not do it, which is why most tours include astrophotography — the guide takes the picture with a camera on a tripod and sends it to you. If you are bringing your own camera, a tripod is not optional and a wide fast lens is what you want.
Frequently asked questions
What months is the Milky Way visible?
The core is up at night roughly March to October, and highest in the middle of the night during the southern winter, which is also the driest and clearest time of year.
Will a full moon stop me seeing it?
Effectively yes. Moonlight washes out the entire structure. Book within a few days of a new moon if you can.
Can I photograph it on a phone?
No. Most tours include astrophotography with a proper camera for this reason.