A night at Chajnantor

This video shows the superbly clear sky of the Chajnantor Plateau, at an altitude of 5000 metres in the Chilean Andes. This extremely high and dry site is home to APEX and ALMA, two observatories probing the sky at millimetre and submillimetre wavelengths — between infrared light and radio waves.

APEX, the Atacama Pathfinder Experiment, is visible as the bright area on the left, whereas the Array Operations Site (AOS) Technical Building of ALMA, the Atacama Large Millimeter/submillimeter Array, is visible on the right. While APEX consists of a single antenna and has been operating since 2005, ALMA is currently being built by ESO and its international partners, and will consist of an array of 66 antennas.

As the night proceeds, the starry sky displays its beauties, including the outstanding shape of the Milky Way; just below the horizon, headlights of cars pass by, as astronomers and engineers on the site are busy working and driving from one facility to the other and further down, to the ALMA Operations Support Facility (OSF), the base camp for the everyday, routine operation of the observatory, located at an altitude of 2900 metres.