Arecibo

Arecibo is a municipality and city on the northern coast of Puerto Rico. It is known internationally for the Arecibo Observatory, a major radio astronomy facility located nearby that contributed to a wide range of scientific research before its collapse in 2020. The city itself is part of the island’s coastal region and serves as a local center for commerce and culture within the surrounding countryside.

The Arecibo Observatory housed a large radio telescope with a fixed, spherical reflector of 305 meters (1,000 feet) in diameter. Built during the 1960s under the sponsorship of Cornell University and later operated by the National Astronomy and Ionosphere Center with support from the National Science Foundation, the facility supported research in radio astronomy, atmospheric science, and radar observations of solar system bodies. It became a prominent site for international collaborations and public science outreach.

Among its notable achievements, the observatory contributed to the discovery of the first binary pulsar, PSR B1913+16, in 1974 by researchers Hulse and Taylor, a discovery that provided key evidence for general relativity. It also hosted the transmission of the Arecibo message in 1974, a symbolic interstellar radio message aimed at demonstrating humanity’s technological capabilities. The facility was a frequent recipient of observing campaigns studying pulsars, galaxies, and near-Earth objects, as well as radar mapping of planets.

In December 2020, the 900-ton platform above the dish collapsed after a series of structural failures, leading to the permanent shutdown and subsequent decommissioning efforts. Since then, the site has remained inactive while plans for salvage and redevelopment have been discussed. The Arecibo municipality continues to be recognized for its historical and cultural significance in Puerto Rico.