THE ARECIBO OBSERVATORY

The Arecibo Observatory is rooted in the will of Professor William E. Gordon of Cornell University (USA) to study a particular layer of the Earth's atmosphere called ionosphere. His research during the 1950 s led him to prioritize the radar method, with a huge fixed reflector with a tower to receive the information collected. The construction of Arecibo Observatory begins in the summer of 1960 and ends three years later. Since then, it has been providing data to the scientific community around the world. When you discover this telescope for the first time, you'll be hit by its huge collector surface, equivalent to about 80,000 m ²! This spherical surface consists of almost 40,000 perforated aluminum panels measuring approximately one meter in two, supported by a network of steel cables stretched through the underlying karst pit. At 137 m above this immense structure is suspended a receiving platform weighing about 900 tons, maintained in air by eighteen cables connected to three reinforced concrete towers. A mobile dome equipped with reflectors shall be fixed: it allows the recording of signals received by the network of radio telescope panels. What are Arecibo's preferred targets? He studies the properties of certain bodies of the Solar System such as planets, comets and asteroids. In our galaxy, it detects pulses issued by some highly atypical stars named "pulsars". Much further, he is able to detect signals issued by some galaxies shortly after the birth of the Universe. Among its main discoveries, there is the precise determination of Mercury's rotation period in 1964, or the first ever radar image of an asteroid in 1989.