Atacama Large Millimeter Array (ALMA) is the largest and most sensitive telescope in the world at millimeter and submillimeter wavelengths. A joint United States-European project, ALMA consists of sixty-six 12-meter and 7-meter dish antennas at an altitude of 5,000 meters near Cerro Chajnantor in northern Chile. The array is configurable with baselines up to 10 kilometers, is capable of imaging in all atmospheric windows between 10 millimeters and 350 microns, and has 10 times the resolution of the Very Large Array (VLA) and the Hubble Space Telescope. The US side of the project is run by the National Radio Astronomy Observatory, while the European side is a collaboration between the European Southern Observatory, the French Centre National de la Recherche Scientifique, the German Max-Planck-Gesellschaft, the Netherlands Foundation for Research in Astronomy and Nederlandse Onderzoekschool Voor Astronomie, and the United Kingdom Particle Physics and Astronomy Research Council.

In June 2002, work began to assemble the first of the ALMA prototype antennas at the ALMA Test Facility located on the VLA site in New Mexico. Among ALMA's numerous uses will be the observation of star-forming regions, protostars, and protoplanetary disks. ALMA will also play an important role in the search for extrasolar planets through accurate astrometry, and possibly even the direct detection of planets and their atmospheres. ALMA was inaugurated on 13 March 2013, and has now begun operation.