Four ALMA antennas on the Chajnantor plain

Four of the first ALMA antennas at the Array Operations Site (AOS), where they are being tested as part of the ongoing Commissioning and Science Verification process. The AOS is located at 5000 metres altitude on the Chajnantor plateau, about 50 km away from San Pedro de Atacama, in the II Region of Chile. The 66 ALMA antennas will be spread across the desert plateau over distances from 200 metres to 16 kilometres, which will give ALMA a powerful variable "zoom". This picture was taken in June 2010. ALMA, the Atacama Large Millimeter/submillimeter Array, is the largest astronomical project in existence and is a truly global partnership between the scientific communities of East Asia, Europe and North America with Chile. ESO is the European partner in ALMA.