Time-lapse of a whole night at the ALMA Array Operations Site (AOS), located at 5000 meters altitude on the Chajnantor plateau, in the II Region of Chile. As the Moon sets at the beginning of the night, three of the first ALMA antennas start tests as part of the ongoing Commissioning and Science Verification process. Because they are pointing at the same target in the sky at any moment, their movements are perfectly synchronized.