WOW! signal from space

The 'Wow' mystery turns 30
Posted: Wednesday, August 15, 2007 8:50 PM by Alan Boyle

Exactly 30 years ago today, astronomer Jerry Ehman was looking over a printout of radio data from Ohio State University's Big Ear Radio Observatory when he saw a string of code so remarkable that he had to circle it and scribble "Wow!" in the margin. The printout recorded an anomalous signal so strong that it had to come from an extraordinary source.

The signal came from the direction of the constellation Sagittarius, and lasted seventy-two seconds at about 1420.456 MHz before it faded away. The volunteer who found and circled the data in the paper printout was Jerry Ehman, who was amazed at the signal's intensity and what a narrow range of frequencies it appeared in. Seventy-two seconds also happened to be the exact length of time it would take for the Earth to rotate the Big Ear through a signal from space. He did some analysis of the data, and by all indications this powerful, narrowband radio signal was from outside of our solar system. But was it sent by an advanced civilization?"Wow" remains the strongest and clearest signal ever received from an unknown source in space, as well as the most fascinating and unexplainable. The signal's original discoverer Jerry Ehman doesn't care to speculate on its source, and he remains scientifically skeptical. "Even if it were intelligent beings sending a signal," he said in an interview, "they'd do it far more than once. We should have seen it again when we looked for it 50 times." Perhaps. But consider that when humankind used the Arecibo radio telescope to send a message out into space in 1974, it was only sent once.