Categories: Guide to Space

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.

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Fraser Cain

Fraser Cain is the publisher of Universe Today. He's also the co-host of Astronomy Cast with Dr. Pamela Gay. Here's a link to my Mastodon account.

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