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Radiotelescopes. By ESO/C. Malin, modified by Krischan

Search for Extraterrestrial Intelligence (SETI)

The search for extraterrestrial intelligence (SETI) is a collective term for the scientific search for intelligent extraterrestrial life. For example, monitoring electromagnetic radiation for signs of transmissions from civilizations on other worlds. There are great challenges in searching the universe for signs of intelligent life, including their identification and interpretation. As various SETI projects have progressed, some have criticized early claims by researchers as being too “euphoric”.

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Wow! signal. By Big Ear Radio Observatory and North American AstroPhysical Observatory (NAAPO). -

Wow! Signal

The Wow! signal is the name given to a strong narrowband radio signal detected by Jerry R. Ehman on August 15, 1977, while he was working on a SETI project at the Big Ear radio telescope of The Ohio State University. The signal bore the expected hallmarks of non-terrestrial and non-Solar System origin. The entire signal sequence lasted for the full 72-second window that Big Ear was able to observe it, but has not been detected since.

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Arecibo Message. By Arne Nordmann (norro) - Own drawing, 2005

Arecibo message

The Arecibo message was broadcast into space a single time via frequency modulated radio waves at a ceremony to mark the remodeling of the Arecibo radio telescope in Puerto Rico on 16 November 1974. The message was aimed at the current location of globular star cluster M13 some 25,000 light years away because M13 was a large and close collection of stars that was available in the sky at the time and place of the ceremony.

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Pioneer 10. By NASA/Ames Research Center, Don Davis (?)

Pioneer 10

Pioneer 10 was an American space probe that completed the first mission to the planet Jupiter. Thereafter, Pioneer 10 became the first spacecraft to achieve escape velocity from the Solar System. It was launched on March 2, 1972. Between 1972-1973, it became the first spacecraft to traverse the asteroid belt.

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Voyager. By NASA


The Voyager program was a famous American scientific program that employed two robotic probes, Voyager 1 and Voyager 2, to study the outer Solar System. They were launched in 1977 to take advantage of a favorable alignment of Jupiter, Saturn, Uranus, and Neptune, and were exploring the outer boundary of the heliosphere.

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