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The Wow! Signal of 1977

During the 1950s over in Ohio, Professor of Electrical engineering and astronomy, Dr John D. Kraus, designed the Big Ear Radio Telescope. It was a prototype that cost 23000 dollars and preceded the building of the Big Ear Radio Observatory. Although the telescope was seated on the roofs of two university buildings, Kraus was eventually granted twenty acres of land to construct the radio observatory. 

The choice of land wasn’t completely random. Its remote location ensured a minimal risk of other interfering radio signals. Because the observatory wasn’t built to pick up radio signals from the earth, or satellites even. No, Dr Kraus hoped his observatory would manage to find proof of extraterrestrial life. 

The project was quite something. From 1956 to 1963 the observatory was constructed, mainly by students in order to reduce the costs. When the observatory, nicknamed ‘Big Ear’, was finally operational it was larger than three football fields. The Big Ear was equipped with two ‘ears’ if you will. On this photograph, you can see them. Generally, if radio signals were received by one ear, after several minutes, the other ear received them as well.

In order to potentially receive radio signals from extraterrestrial life, Kraus first had to map outer space for radio waves. It was quite the pioneering project and only after ten years, in 1973, was it completed. From then on they could ‘monitor’ these wavelengths, to detect radio transmissions that potentially originated from extraterrestrial entities.

It wasn’t until four years later that the Big Ear Radio Telescope detected a signal that was… unusual to say the least. The radio telescope received a powerful unidentified signal on August 15th 1977. Because of the technology used back then instead of acting on radio signals immediately, astronomers would look at a cluster of radio signals that had been picked up in the past couple of days. Usually, these were all somewhat predictable and the same. But astronomer Jerry Ehman, going over the documentation of the past couple of days noticed the unusual signal. The powerful narrowband radio signal, expressed as a string of code, captures his attention.

The signal contained signs of potential extraterrestrial origins, and certainly a source that wasn’t within our solar system. In total, the signal lasted 72 seconds. Because of how spectacular it was Ehman, circled it and wrote “Wow!” next to it. From then on the signal was known as the Wow! Signal. 

So why was this seemingly innocuous string of letters- and numbers so special? Well, several things about it are unusual. I am going to get into the technicalities for a short bit – so bear with me. Basically, the string of code, the 6EQUJ5, portrays the intensity of the signal. The graph you’re seeing right now visualizes that intensity. The numbers between 1 to 9 indicate the variation of intensity between 1.000 and 9.999, above 10 the intensity is indicated by a letter, in this case A for 10.0 to 10.999, B for 11.0 to 11.999 and so on. Right, so the strength of this signal had several values. Generally a .5 error margin is included: 6 being 6, E being 14.5, Q being 26.5, U being 30.5, J being 19.5 and 5 as 5.5. In the colour chart that is on-screen right now you can see the exceptional values. The short Wow! Signal burst is in the bottom left. 

Those strings of numbers don’t really say anything, until you know that when Big Ear received the peak of this signal’s intensity, namely U (between 30 and 31), it was the highest measured intensity by a radio telescope… ever. So, the intensity of this number is literally devoid of any dimension.

Because the Big Ear is a stationary telescope that scans space through the earth’s rotation, it observes a limited area. The maximum amount of time to observe an object was 72 seconds before the earth’s rotation moved the telescope away from it. Knowing this, it was hypothesised that any signal that lasted for exactly 72 seconds, would have a rising intensity for the first 36 seconds before it reached the core of the telescope, only to proportionately lose intensity the next 36 seconds. Both the length of the Wow! Signal, namely 72 seconds, as the trajectory of the signal’s intensity corresponded with the expectations of a signal of extraterrestrial origin.

Scientists have not been able to find the source of the signal. Since 1977 no such similar signal has been detected. It was received from a part of space where you wouldn’t expect any radio waves of the sort. What’s curious as well is that although the first ear received it, the second ear never confirmed the signal passed. This indicates that the signal was abruptly cancelled.

The SETI – Search for extraterrestrial intelligence is a term for scientific searches for intelligent extraterrestrial life. SETI has not been able to explain the source of the radio signal for the past 40 years. Now, the sole purpose of SETI is to identify signals such as this one, and the Wow! Signal is the only one of all those years of which the source has not been located. 

Now, there is an understandable reason for why after over 40 years nobody can say where the signal originated. It has only been detected once. So astronomers that investigate it, bump into the same problem over and over again. In the words of an astronomer: “image if you hear a sound in your basement one night, but you cannot find its source and it never appears again, then it’s near impossible to discover what made the sound.” And until another signal such as this one is detected its origin will most likely never be found.

Because there is no obvious source for the signal, many scientists theorise about its origins. The past four decades have seen many theories. Obviously, the most exciting one is that of extraterrestrial life that sent the powerful short signal. Yet other theories are perhaps a little bit more plausible. Many scientists claim that it is probably because of human interference that disturbed the activities of the radio telescope which led to the curious signal. Because of the contents of the signal: a strong radio signal on a very narrow frequency, which means that it has a specific wavelength. Generally, this is seen with electronic devices or fighter jets. Yet there are particular ways that signals from the earth can be filtered out from the signals Big Ear receives. And those filters have been used on the Wow! Signal… many times of the past years. And time and time again the signal proves that it did, in fact, originate in space.

In 2015 the scientists Paris and Evans published a new theory in an attempt to explain the origins of the Wow! Signal. A hydrogen cloud surrounding a comet could explain it. Back in 1977, the astronomers hadn’t detected any comets in the area that was scanned by Big Ear. It was in 2006, nearly 30 years later, when recalculating orbits of comets, it was determined two of them, the 266P/Christensen and the p/2008 Y2 (Gibbs) must have been in the area where the Wow! Signal originated.

Other scientists generally disagree with this theory because of two reasons. Firstly, comets are not known to produce signals with this type of intensity, nor on the wavelength that the signal was received on. And secondly, if it was a comet then the second ‘ear’ of Big Ear should have received the same signal after 70-odd seconds. That didn’t happen. And it’s impossible for a comet to disappear from Big Ear’s range within this timeframe. 

As for the Big Ear Radio Observatory, its scientists were included in the Guiness Book of Records thanks to their prolonged search for extraterrestrial life. The university sold the land the observatory was built on in 1983, and the land developers had different things in mind for it. In order to expand a nearby golf course and construct hundreds of homes they demolished the Big Ear Radio Observatory in 1998. And, well, other observatories around the world are still searching for unknown radio signals that could indicate extraterrestrial life, but so far none have been found. Well over 40 years after the Wow! Signal was received; it remains one of our closest encounters with potential extraterrestrial life. But fortunately for those curious about extraterrestrial life: SETI-telescopes are continuously scanning space for unusual radio signals. So if another Wow! Signal were to be transmitted, the modern technological improvements most likely would be able to determine where it came from.

A. Paris, E. Evans: Hydrogen Clouds from Comets 266/P Christensen and P/2008 Y2 (Gibbs) are Candidates for the Source of the 1977 “WOW” Signal. Journal of the Washington Academy of Sciences, Winter 2015

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