Project Ozma was a search for extraterrestrial intelligence (SETI) experiment started in 1960 by

Cornell University Cornell University is a Private university, private Ivy League research university based in Ithaca, New York, United States. The university was co-founded by American philanthropist Ezra Cornell and historian and educator Andrew Dickson W ...

astronomer

Frank Drake Frank Donald Drake (May 28, 1930 – September 2, 2022) was an American astrophysicist and astrobiologist. He began his career as a radio astronomer, studying the planets of the Solar System and later pulsars. Drake expanded his interests ...

, at the National Radio Astronomy Observatory, Green Bank at Green Bank, West Virginia. The object of the experiment was to search for signs of life in distant

planetary system A planetary system is a set of gravity, gravitationally bound non-stellar Astronomical object, bodies in or out of orbit around a star or star system. Generally speaking, systems with one or more planets constitute a planetary system, although ...

s through interstellar radio waves. The program was named after Princess Ozma, ruler of the fictional

land of Oz The Land of Oz is a fantasy world introduced in the 1900 children's novel ''The Wonderful Wizard of Oz'' written by L. Frank Baum and illustrated by William Wallace Denslow, W. W. Denslow. Oz consists of four vast quadrants, the Gillikin Countr ...

, inspired by L. Frank Baum's supposed communication with Oz by radio to learn of the events in the books taking place after ''

The Emerald City of Oz ''The Emerald City of Oz'' is the sixth book in L. Frank Baum's List of Oz books, Oz series. Originally published on July 20, 1910, it is the story of Dorothy Gale and her Uncle Henry and Aunt Em coming to live in Oz permanently. While they are t ...

''. The search was publicized in articles in the popular media of the time, such as ''Time'' magazine and was described as the first modern SETI experiment. Drake used a radio telescope with a diameter of to examine the stars Tau Ceti and Epsilon Eridani near the 1,420 MHz marker frequency, the equivalent of wavelength of 21 centimeters which corresponds to the energy of a photon emitted from a hydrogen atom during "spin-flip" transition. Both are nearby Sun-like stars that then seemed reasonably likely to have inhabited planets. A 400 kilohertz band was scanned around the marker frequency, using a single-channel receiver with a bandwidth of 100 hertz. The information was stored on tape for off-line analysis. Some 150 hours of intermittent observation during a four-month period detected no recognizable signals. A false signal was detected on April 8, 1960, but it was determined to have originated from a high-flying aircraft. The receiver was tuned to wavelengths near 21 cm, which is the wavelength of radiation emitted naturally by interstellar hydrogen; it was thought that this would be familiar, as a kind of universal standard, to anyone attempting interstellar radio communication. A second experiment, called Ozma II, was conducted with a larger () telescope at the same observatory by Patrick Palmer and Benjamin Zuckerman, who intermittently monitored 670 nearby stars for about four years (1972–76). They examined a 10 MHz bandwidth with 52 kHz resolution and a 625 kHz bandwidth with 4 kHz resolution. The spectrometer was centered on the 21 cm hydrogen line in the rest frame of each observed star.

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