The Very Large Array (VLA) is one of the world’s premier astronomical radio observatories. The VLA consists of 27 antennas arranged in a huge Y pattern up to 22 miles (36 kilometers) across—roughly one-and-a-half times the size of Washington, D.C. Each antenna is 81 feet (25 meters) in diameter; they are combined electronically to give the resolution of an antenna 22 miles (36 kilometers) across, with the sensitivity of a dish 422 feet (130 meters) in diameter. Each of the 27 radio telescopes in the VLA is the size of a house and can be moved on train tracks. In its twenty-second year of operation, the VLA has been one of the most productive observatories with more than 2,200 scientists using it for more than 10,000 separate observing projects. The VLA has been used to discover water on the planet Mercury, radio-bright coronae around ordinary stars, micro-quasars in our galaxy, gravitationally induced Einstein rings around distant galaxies, and radio counterparts to cosmologically distant gamma-ray bursts. The vast size of the VLA has allowed astronomers to study the details of super-fast cosmic jets, and even map the center of our galaxy.