Free Astronomy Magazine September-October 2020

34 SEPTEMBER-OCTOBER 2020 ASTROBIOLOGY (which includes the Carl Sagan Center) was founded in 1984, it represents only a small part of the SETI world. In fact, it numbers less than 100 scientists, while thousands of oth- ers have dedicated themselves to similar re- search at hundreds of other institutes. Historically, the birth of SETI dates back to 1960, the year in which the astronomer Frank Drake started Project Ozma, which planned to use the Green Bank 26-meter radio telescope (West Virginia) to “listen” for possible messages from Tau Ceti and Epsilon Eridani stars. Drake was probably in- spired by a theoretical work of the previous year, performed by Philip Morrison and Giuseppe Cocconi, who suggested that any extraterres- trial civilizations could use radio sig- nals to communicate with us. To tell the truth, this idea was not very original - in fact, it had already been proposed in the early 1900’s by Guglielmo Marconi, Lord Kelvin and David Peck Todd, who proposed to use radio waves to contact a possible Martian civilization. The search for artificial radio signals from space has been the cornerstone of all SETI projects, at least until the invention and development of the laser, which was imme- diately considered an alternative technology that an extraterrestrial civilization could choose to communicate with in the visible spectrum rather than the radio spectrum. It is quite evident that SETI projects have al- P hysicist Giu- seppe Cocconi was one of the first scientists to propose SETI strategies. [CERN] Below, as- tronomer Frank Drake and his fa- mous formula, which allows us to estimate the number of tech- nological civiliza- tions in our galaxy.