ALMA (Atacama Large Millimeter/submillimeter Array) is a gigantic radio-telescope made up of 66 12 m and 7 m parabolic antennas, all mobile and interconnected. Situated in Chile at an altitude of 5,200 m (17,060 feet), it extends over 16 km and enables scientists to obtain images of radio sources with an unequalled resolution. It is a world-scale project, with participation from Europe, the United States, Canada and Japan. French astronomers also have access in the northern hemisphere to the two instruments of the French-German-Spanish Institut de RadioAstronomie Millimétrique (IRAM): the interferometer on the Bure plateau in the Alps, which has eight 15 m mobile antennas, whose number will increase gradually to 12, and to the 30 m Sierra Nevada radio-telescope in Spain.
