Radio telescopes in Arecibo - currently the largest in the world (using one of the aperture). The telescope is used for research into astronomy, physics of the atmosphere and radar observations of solar system objects. Astronomical Observatory of Arecibo in Puerto Rico is located 15 km from Arecibo, at an altitude of 497 meters above sea level. Research conducted by Cornell University in cooperation with the National Science Foundation (USA). The Observatory is also a National Centre for Astronomy and Ionosphere US.