Arecibo Observatory

Arecibo Observatory, large, stationary radio telescope, with attendant facilities, that is part of Cornell University's National Astronomy and Ionosphere Center (NAIC). The telescope, located 15 km (9 mi) south of Arecibo on the northern coast of Puerto Rico, is a bowl-shaped dish set into a natural hollow. The dish, 305 m (1,000 ft) wide, consists of nearly 40,000 individual reflecting panels attached to a network of steel cables. The panels focus incoming radio waves from outer space onto a detecting platform suspended above the dish. The platform can be adjusted to enable the telescope to observe the sky from 43° North to 6° South.

The observatory was completed by Cornell University in 1963 and is operated under contract with the National Science Foundation. The telescope is used for studying Earth's upper and middle atmospheres as well as sources of radio waves in deep space (see Radio Astronomy). It has also been used to search for radio signals that would indicate the existence of extraterrestrial life (see Astrobiology). The equipment can also transmit radio signals and has been used for radar-reflection studies of the Moon as well as of planets, comets, asteroids, and other bodies in the solar system.

In 1997, engineers and scientists completed a five-year project to upgrade the Arecibo observatory. They installed two new reflecting panels on the telescope, making it four times more sensitive to deep space radio signals than before the upgrade. Radio astronomers can use this increased sensitivity for more extensive observations and studies.