Arecibo Telescope

Completed in November 1963 near Arecibo, Puerto Rico, this giant radio telescope was built into a natural karst sinkhole with a 305-meter fixed reflector and a suspended platform that let it track part of the sky. Developed from late-1950s Cold War research, it became a major instrument for radio astronomy, radar astronomy, ionospheric study, planetary science, atmospheric research, SETI programs, and near-Earth object detection. For 53 years it was the world’s largest single-aperture telescope and one of the most recognizable scientific structures. After reduced funding, storm damage, earthquakes, and two cable failures in 2020, the structure collapsed on December 1, 2020.

Puerto Rico · Puerto Rico