This web site has been selected for viewing by visitors to the Arecibo Observatory in Arecibo, Pureto Rico. As site of the world's largest single-dish radio telescope, the Observatory is recognized as one of the most important national centers for research in radio astronomy, planetary radar and terrestrial aeronomy. Opened in 1963, the observatory utilizes a reflective metalic array lining the caldera of an extinct volcano as the telescope's dish. The microwave antenna, used for transmitting and receiving radio signals, is suspended from massive cables above the dish. Some data from the Arecibo Observatory feeds the massive Search for Extraterrestrial Intelligence (SETI) project known as SETI@Home. This project has enlisted more than 1.7 million volunteers world-wide who analyze fragments of the Arecibo data on their home PCs, looking for indications of radio transmissions from distant galaxies. As of February, 2000, more than 76 million data fragments have been analyzed. No extraterrestrial signals have been found ... yet. Back