Arecibo Observatory

Arecibo ObservatoryThe 305-metre (1,000-foot) radio telescope at the Arecibo Observatory, Puerto Rico. The central platform of the telescope collapsed in 2020.

Arecibo Observatory, astronomical observatory located 16 km (10 miles) south of the town of Arecibo in Puerto Rico. It was the site of the world’s largest single-unit radio telescope until FAST in China began observations in 2016. This instrument, built in the early 1960s, employed a 305-metre (1,000-foot) spherical reflector consisting of perforated aluminum panels that focused incoming radio waves on movable antenna structures positioned about 168 metres (550 feet) above the reflector surface. The antenna structures could be moved in any direction, making it possible to track a celestial object in different regions of the sky. The observatory also has an auxiliary 12-metre (39-foot) radio telescope and a high-power laser transmitting facility used to study Earth’s atmosphere.

Arecibo Observatory after collapse
Arecibo Observatory after collapseAerial view showing the damage at the Arecibo Observatory's 305-metre (1,000-foot) radio telescope in Arecibo, Puerto Rico, after one of the main cables holding the receiver broke, on December 1, 2020. The 900-ton receiver platform fell 140 metres (450 feet) and smashed onto the radio dish below. In October 2022, the National Science Foundation announced the radio telescope would not be rebuilt.

In August 2020 a cable holding up the central platform of the 305-metre telescope snapped and made a hole in the dish. After a second cable broke in November 2020, the National Science Foundation (NSF) announced that the telescope was in danger of collapse and the cables could not be safely repaired. The NSF thus planned to decommission the observatory. On December 1, 2020, days after the NSF’s announcement, the cables broke, and the central platform collapsed into the dish. In October 2022 the NSF announced that it would not rebuild the telescope but would instead build an educational centre at the site.

Mercury's north pole
Mercury's north poleMercury's north polar region, in a radar image obtained with the Arecibo radio telescope. All the bright (radar-reflective) features are believed to be deposits of frozen volatile substances, likely water ice, at least several metres thick in the permanently shaded floors of craters.

Scientists using the Arecibo Observatory discovered the first extrasolar planets around the pulsar B1257+12 in 1992. The observatory also produced detailed radar maps of the surface of Venus and Mercury and discovered that Mercury rotated every 59 days instead of 88 days and so did not always show the same face to the Sun. American astronomers Russell Hulse and Joseph H. Taylor, Jr., used Arecibo to discover the first binary pulsar. They showed that it was losing energy through gravitational radiation at the rate predicted by physicist Albert Einstein’s theory of general relativity, and they won the Nobel Prize for Physics in 1993 for their discovery.

The Editors of Encyclopaedia BritannicaThis article was most recently revised and updated by Erik Gregersen.
Citation Information
Article Title: Arecibo Observatory
Website Name: Encyclopaedia Britannica
Publisher: Encyclopaedia Britannica, Inc.
Date Published: 18 October 2024
URL: https://www.britannica.comhttps://www.britannica.com/topic/Arecibo-Observatory
Access Date: November 21, 2024