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Arecibo Observatory
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<p>The Arecibo Observatory, also known as the National Astronomy and Ionosphere Center (NAIC) and formerly known as the Arecibo Ionosphere Observatory, is an <a href="/facts/Observatory/y0FVg7vS">observatory</a> in <a href="/facts/Esperanza,_Arecibo,_Puerto_Rico/Ttl4mPnB">Barrio Esperanza</a>, <a href="/facts/Arecibo,_Puerto_Rico/jnrm6h8c">Arecibo, Puerto Rico</a> owned by the US <a href="/facts/National_Science_Foundation/FlDT8TbW">National Science Foundation</a> (NSF). </p><p>The observatory's main instrument was the <a href="/facts/Arecibo_Telescope/gkK6QE9G">Arecibo Telescope</a>, a 305 m (1,000 ft) <a href="/facts/Spherical_reflector/X1c0aVmK">spherical reflector</a> <a href="/facts/Dish_antenna/8EpLcN6q">dish</a> built into a natural <a href="/facts/Sinkhole/yrjCajL2">sinkhole</a>, with a cable-mount steerable receiver and several <a href="/facts/Radar/jk9BTbFA">radar</a> transmitters for emitting signals mounted 150 m (492 ft) above the dish. Completed in 1963, it was the world's largest single-aperture telescope for 53 years, surpassed in July 2016 by the <a href="/facts/Five-hundred-meter_Aperture_Spherical_Telescope/6ASExc9E">Five-hundred-meter Aperture Spherical Telescope</a> (FAST) in China. On August 10 and November 6, 2020, two of the receiver's support cables broke and the NSF announced that it would decommission the telescope. The telescope collapsed on December 1, 2020. In 2022, the NSF announced the telescope will not be rebuilt, with an educational facility to be established on the site. </p><p>The observatory also includes a smaller <a href="/facts/Radio_telescope/SxIXUowL">radio telescope</a>, a <a href="/facts/Lidar/b9SPUmLM">LIDAR</a> facility, and a visitor center, which remained operational after the telescope's collapse. The asteroid <a href="/facts/4337_Arecibo/R8aXWvkK">4337 Arecibo</a> is named after the observatory by <a href="/facts/Steven_J._Ostro/k5SMwybl">Steven J. Ostro</a>, in recognition of the observatory's contributions to the characterization of Solar System bodies. </p>