Various methods have been tried to identify extraterrestrial living organisms.
In the solar system, they search for traces of living organism, analyze images of planets and satellites, and send probes to potential places such as Martian and Saturn’s secondary planet called Titan.
Outside of the solar system, SENTI (Search for extraterrestrial intelligence) is the center of the survey, and various plans are being implemented, such as operating the sky to check for radio signals emitted by aliens.
Exploration has begun to see if planets resembling the Earth have orbited nearby fixed stars.
Lastly, CENTI (Communication with extraterrestrial intelligence) sends a signal to the target star and sends out the existence of Homo sapiens.
In 1974, a CENTI Arecibo message in binary code was sent to the M13 star cluster, 21,000 light-years away. The Arecibo message contains symbols representing the human body, DNA, solar system, Arecibo Observatory, etc.
In 1999, a more complex “Encounter 2001” message was sent from a Ukrainian radio telescope to some of the nearby fixed stars resembling the sun.
Even if an alien receives this message, it will take at least 100 years for us to receive a reply.