What Was the WOW Signal?

What was the signal received in 1977? Was it a cryptic message from an alien civilization?

In 1977, radio astronomer Jerry Ehman was looking through observation data from the Big Ear Radio Telescope. He was searching for evidence that alien civilizations might be trying to communicate using radio waves as an alternative to metal probes.

Specifically, that aliens would be communicating in a portion of the radio spectrum that mimics hydrogen.

The search generated an immeasurable mountain of remarkably boring data, nothing but the background radio transmissions of the Universe.

But then he saw a data signal so interesting and unique that he circled it and wrote “WOW” in a red pen. A red pen! There was an exclamation point! Only one, though, don’t get too excited.

Ehman circled the characters “6EQUJ5”, distinguishing them from all the other 1s and 2s on the field of data.

What does this code mean? Is it a cryptic message from an alien civilization? Why does it start with a 6 and then end with a 5? What are they trying to tell us?

From the moment Ehman red-penned in WOW, this has been known as the WOW Signal, and it’s been the cause of much speculation by SETI researchers and aliens fans and confusion for World of Warcraft players around the globe.

For starters, it’s important to understand that the Big Ear Radio Observatory didn’t actually receive these characters in a message. The Observatory was listening to radio signals coming from a region of the sky in the Constellation Sagittarius, near the M55 globular cluster.

Each character on this chart corresponds to about 10 seconds of “listening”. If the telescope picked up a signal, it recorded the intensity with a single character. The scale went from 1 to 9, and then through A to Z. The highest ever recorded was U.

So, when you look at this chart, what you’re actually seeing is mostly no radio signal, and then the signal gets brighter and brighter, as the Big Ear’s dish passed whatever was generating the signal, then it gets dim again.

When astronomers tried to follow up, the signal was gone. It happened just this one time, and then not anything else like it, not from this region, or any other region in the the sky.

Hurry up Fraser! Was it aliens? I have to know. I need to put it on the blog l moderate for my favourite death metal conspiracy band “Tinfoil Hate”.

Dr. Ehman, and other astronomers searched that region more than 50 times, trying to detect any signal.


They used the Big Ear again, and then the Oak Ridge Observatory, and even the vastly more powerful Very Large Array.

Ehman himself was doubtful it was intelligent in nature. He wasn’t even sure it came from outside the Solar System at all. He suspected it was either a classified military satellite or a reflection of an Earth-based radio signal bouncing off space debris.

But that doesn’t really explain it very well, does it Scully?

If it was a satellite transmitting in this spectrum, you would expect to see it get picked up in other locations around Earth and at other times.

It’s never been seen again.

It makes sense that aliens would communicate in this spectrum; it’s what we’d do if we wanted to send an unambiguous message out into space.

The signal is a point source, which means it would have come from a specific star or planet in the Milky Way.

The bottom line is that we’ll never know. There just isn’t any more data to help us understand this mystery any more deeply.

I’m a huge fan of searching for signals from extraterrestrial civilizations, and tantalizing mysteries like this means we should keep looking. Whether or not we discover new alien friends, or unusual new natural sources of radio emissions, the search is worth doing.

One last thing.

Just for fun, in 2012 researches used the Arecibo Observatory to send a signal from Earth containing messages, tweets and photos in the direction that the WOW Signal originated from to guarantee that aliens send their space meat harvesters straight to Earth.

I hope the aliens enjoyed it, and think about us with a note of sadness as they follow up with the deployment of the Hyperspace Construction Fleet towards our mostly harmless planet.

Sadly, the mysterious WOW Signal isn’t clear cut evidence that alien civilizations are trying to broadcast in our direction. Instead, it’s more likely we’re just polluting space itself with more junk and radio signals.

Time for another prediction. When do you think we’ll detect a signal from an alien civilization. Give us your best guess in the comments below.

Thanks for watching! Never miss an episode by clicking subscribe. Our Patreon community is the reason these shows happen. We’d like to thank Ockie Simmonds and the rest of the members who support us in making great space and astronomy content. Members get advance access to episodes, extras, contests, and other shenanigans with Jay, myself and the rest of the team. Want to get in on the action? Click here.

10 Replies to “What Was the WOW Signal?”

  1. Phantastic, we’ve found a… a…. yeah, we’ve found it! A single burst of radio frequency! Sadly we cannot say if this signal has some information, because…we’ve lost it! Reminds me of Jocelyn Bell and her “LGM” 😉
    “Open all frequencies again, Uhura!”
    I hope the 1st real signal will be detected when the world will be ready for it. No more local warlords pretending to fight in the name of some “god, allah, jehova, the green cookie..” and we’re matured… ripe for IT !
    Sadly.. I will not live long enough for that!

  2. I wonder if it was a gamma ray burst? I understand that radio signals are on the opposite end of the electromagnetic spectrum, but I imagine that gamma ray bursts put out energy across the entire spectrum. It would make sense in terms of it flaring once, and never being seen again.

    1. We did the same thing with our 1974 Arecibo Broadcast. Anyone intercepting that signal between here and its target, M-13, would get a one off signal, much lie the WOW signal. If they don’t have a strong enough receiver to pick up the rest of the stuff leaking into space, it would leave their SETI researchers scratching their heads, or tentacles!

  3. In 1974, we sent out a message to the M-13 Globular Cluster, 21,000 LY away. If that message gets intercepted by anyone that happens to be listening in between, wouldn’t that be a ‘WOW’ signal to whoever receives it? Unless they had a powerful enough receiver, they would not necessarily pick up our ‘radio leakage’. Maybe the ‘WOW’ signal was a similar technological civilization sending out similar information as to our 1974 broadcast? The 2012 message sent in the direction of the WOW signal is only 3LY out by now. It would not have even reached the closest stars yet! Since we don’t know how far away the WOW signal originated, we may be waiting awhile for any response! Ironically, as our broadcasts go digital, we are becoming more ‘silent’. That suggests any technologically advanced civilization that follows a similar technological evolution as ours would only be ‘heard’ for about 100 years. That is a very narrow period of time to be able to pick anything up.

  4. My best guess is we are more likely to receive a continuous string of data from some far away alien broadcast as opposed to a specific message aimed at us. Much as some alien life form might discover our TV or radio broadcasts. It will seem like random gibberish if we do receive it, simply because we will have no idea how they modulate their transmissions, and even when we discover how they do, we won’t know what they’re saying. Star Trek aside, no one on Earth speaks ‘alien’ yet.

    If and when we do receive such signals, two factors will be certain. One, it will be extremely weak in signal strength, coming all that distance from however many light years away it might be. A minimum of 4.3; a maximum of who knows? Hundreds is a good guess. Thousands? Probably too far to receive it.

    Two, we won’t just get a fast hit like 1977, because it will be a continuous broadcast meant for their own kind, like our TV shows are meant for us.

    My own feeling is that some form if life capable of sending such signals is indeed out there. But the vast distance of space simply makes it unlikely we’ll ever hear from them or receive a visit from them. We’re far more likely to receive a signal from a prankster here on earth, and any UFO encounter is most likely to be a secret military aircraft not yet seen by the public.

  5. It will be sooner than you think and take form…
    Greetings Earthlings,
    Nude gurls from EVERY system in the Galaxy! Start your FREE trial now!

    1. Either that or some kind of PDS (Pizza Delivery Service). You might also have a look-out for a Vogon calling his Brain Specialist.

    2. Take this cheap pill for a firmer spore pouch!

      Exoskeletologists hate her! Housewife from Theta Corvi discovered this one weird trick!

      Greetings! I hope the Great Maker smiles upon you this day! My name is qzz’Rhltr’blep and I am a wealthy industrialist who needs help transferring my nano-credit chips out of my country…

Comments are closed.