Tiny observers in a vast desert

ALMA is a revolutionary astronomical telescope, comprising an array of 66 giant 12-metre and 7-metre diameter antennas observing millimetre and submillimetre wavelengths. It was built on the breathtaking Chajnantor Plateau, at an altitude of around 5000 metres in the Chilean Andes, making it the world's highest major observatory. Chajnantor has an extreme climate; the atmosphere above the plateau is the driest in the world with the exception of Antarctica.