ALMA radio astronomy antennas. ALMA (Atacama Large Millimeter/sub-millimeter Array) is an array of 66 radio antennas located at an elevation of 5000 meters on the arid Chajnantor plateau in the Chilean Andes. Data from the separate antennas is combined by interferometry, making it one of the most powerful telescopes in the world. In the night sky at left is the Large Magellanic Cloud and the two bright stars at right are Alpha and Beta Centauri. Photographed in November 2011.