In the microwave band, relatively new to interferometers, we’ve got the sixty-six antennas of ALMA, the Atacama Large Millimeter Array, in the remote Andes Mountains of northern Chile. Tuned for wavelengths that range from fractions of a millimeter to several centimeters, ALMA gives astrophysicists high-resolution access to categories of cosmic action unseen in other bands, such as the structure of collapsing gas clouds as they become nurseries from which stars are born.
