The Arecibo Observatory is an observatory in Arecibo, Puerto Rico, also known as the National Astronomy and Ionosphere Center (NAIC). It is owned by the US National Science Foundation (NSF).

The main instrument of the observatory was the Arecibo Telescope, a 305 m (1,000 ft) spherical reflector dish built into a natural sinkhole, a cable-mount steerable receiver mounted 150 m (492 ft) above the dish, and several radar transmitters for emitting signals. Completed in 1963, the Arecibo Telescope was the world's largest single-aperture telescope for 57 years, surpassed in July 2016 by the Five-hundred-meter Aperture Spherical Telescope (FAST) in China. The Arecibo Telescope suffered catastrophic structural failure on December 1, 2020 after two cable breaks in the previous months. The Observatory also includes a radio telescope, a Lidar facility, and a visitor's center which are expected to remain operational after assessing the damage from the main telescope collapse. The observatory was an icon of the Puerto Rican space and science industry.

Buy me a coffee Donate via Pay