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SETI
- Allen Telescope Array
- Optical SETI
- Interstellar Message Construction
- Project Phoenix 1995-2004
- Background Science
- History of SETI
- Center for SETI Research Team
- Other people doing SETI
- Hollywood's View of SETI
History of Interstellar Messages
Messages: From the Moon, to Mars, to the Stars
The earliest speculations about communication with extraterrestrial intelligence (ETI) involved contact with the Moon and with other planets of our own solar system. In the 1800s, many astronomers thought that — at least theoretically — life might well exist throughout the solar system. But when people raised the question of whether we are really alone in the solar system, they began to imagine ways to find a very concrete answer.
Do We Broadcast Messages?
Project Phoenix, like all SETI efforts, is a passive experiment, designed only to look for signals, not to send them. However, humankind has been unintentionally transmitting signals into space - primarily high-frequency radio, television, and radar - for more than fifty years. Our earliest TV broadcasts have reached several thousand nearby stars, although any alien viewers would have to build a very large antenna (thousands of acres in size) to detect them.
Arecibo Message
In 1974, the most powerful broadcast ever deliberately beamed into space was made from Puerto Rico. The broadcast formed part of the ceremonies held to mark a major upgrade to the Arecibo Radio Telescope. The transmission consisted of a simple, pictorial message, aimed at our putative cosmic companions in the globular star cluster M13. This cluster is roughly 21,000 light-years from us, near the edge of the Milky Way galaxy, and contains approximately a third of a million stars.