The “Wow!” signal

August 15, 1977. Jerry Ehman is analyzing computer printouts from the Big Ear radio telescope at Ohio State University. He is not being paid for his work because he is a volunteer but he believes strongly that the work is important and he dutifully pours over each transcript. He taps his pencil against the table, sips his coffee and adjusts his glasses as he flips through each page. Masking the mechanical hum of the instruments in the lab a small transistor radio picks up the Cleveland Indians game against Oakland; the Indians are up 7-1 in the top of the 5th. Outside his window a grounds keeper is mowing the commons and the smell of warm, freshly cut grass filters in through the air conditioning unit.

No runs score in the fifth. The radio plays an ad for the Star Wars movie. Jerry separates each page into two piles - one for further investigation and another, much larger pile for trash. Most of the signals are just background noise, the signals of distant stars and interference printed off as 1’s and 2’s in vertical columns. The more interesting signals usually turn out to be pulsars, dying stars emitting massive amounts of electromagnetic radiation like a lighthouse with a lamp that can rotate as quickly as once every 33 milliseconds and be seen halfway across the universe. Sometimes the telescope picks up terrestrial noise or a weather satellite as it passes overhead. To an untrained eye this could seem like an extra-terrestrial signal but Jerry has analyzed thousands of signals and is not easily fooled.

The Indians leave the bottom of the 6th inning still up 7-1. A couple of research scientists outside his office door wave at Jerry as they pass by. He thinks about getting lunch soon, maybe grab a beer too. Then near then bottom of the stack amidst all the 1’s and 2’s he spots a 6 and circles it with his pencil. Further down is another 6 followed by the vertical series “AEQUJ5? with a 6 and 7 off to the right. On the radio Oakland scores a run at the top of the 7th but Jerry is no longer listening to the game. He checks the printout again. He’s stopped tapping his pencil against the desk and has forgotten about that beer. He quickly looks up to see if the scientists are still outside his door but he’s alone and even the grounds keeper is just a distant shadow at the far end of the commons. Without thinking he writes the word “Wow!” in the margin.

30 years later this signal has never been heard again. Was it a fluke, a glitch, a terrestrial signal being bounced off space debris or was it contact? Dr. Jerry Ehman did state the possibility of the signal coming from Earth “We should have seen it again when we looked for it 50 times. Something (?) suggests it was an Earth-bound signal that simply got reflected off a piece of space debris.” Countering his own skepticism he has stated that since the signal was transmitted at the protected frequency of 1420MHz and due to the unlikely nature of such a signal being bounced off of debris at that declination he still can’t rule out the nature of the signal being extra-terrestrial in nature. “It was the most significant thing we had seen.” he has been quoted as saying.

In 1974 we humans sent our own signal to the stars. Using the powerful Arecibo Radio Telescope the message “was sent only once, over a period of about three minutes, on a narrow beam directed toward a group of about 300,000 stars called the Great Cluster in Hercules, Messier 13. The globular cluster is 25,000 light-years away in our galaxy, the Milky Way. So far, moving at the speed of light, the message has traveled only one thousandth of the distance, or about 147 trillion miles. There are stars closer to our solar system than that, but none of them is in the path of the message.” The chances of an alien civilization “tuning” into this broadcast are pretty slim since the globular cluster it was aimed at will have moved out of the way by the time the signal reaches it.