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Message to Stars Was Sent 25 Years Ago
By Kenneth Silber
Staff Writer
posted: 06:04 am ET
15 November 1999
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arecibo_messageA quarter century ago Tuesday, astronomers sent a powerful transmission into space in hopes that someday the message would be received by an extraterrestrial civilization far away. The Arecibo Radio Telescope broadcast the signal on November 16, 1974 during a ceremony marking an upgrade of the Puerto Rico-based telescope. The transmission can be arranged into a diagram showing, among other things, a human stick figure, the solar system, the telescope itself and the DNA molecule. The signal was "about a million times stronger than the typical TV transmission," says Frank Drake, the astronomer who organized the project. As such, he notes, it outshines the sun at a comparable wavelength and could be detected with technology similar to radio telescopes on Earth. Drake, who is now president of the SETI Institute and a professor at the University of California in Santa Cruz, thinks that listening for radio signals -- which is what most Search for Extraterrestrial Intelligence projects do -- is more important than sending signals. "Transmitting is very costly," he says. "Receiving is not." Moreover, he notes, the huge distances involved mean that any reply to a message would likely take thousands of years to get to Earth. The Arecibo message was sent toward M13, a star cluster some 25,000 light-years away, which means that it will take 25,000 years to get there. However, the signal will pass near some 30 stars along the way.
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