View of some of the dish antennae which make up the Very Large Array (VLA) radio telescope near Socorro, New Mexico. The VLA is the world's largest radio telescope array, consisting of 27 dish antennae, each one 25 metres in diameter. The dishes can be moved to various positions along the arms of a Y-shaped railway network; two of these railway arms are 21 km in length, the third 19 km. The data obtained by the dishes are combined by computer to form a single radio image, so that the 27 antennae in effect form one single giant radio dish.