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The Wow! Signal - Alien Radio

The Search for Extraterrestrial Intelligence Institute (SETI) has been going strong since the early 80s. That does not mean that humans haven't been looking for neighbors from the sky since time immemorial.

Whether we thought the gods, ancestors, spirits, or aliens lived above us, we've tried to find proof of their presence. In 1977, radio astronomer, Jerry Ehman, thought that he had found exactly that. This is the story of the Wow! signal.

Big Ears for Big Space

The Big Ear Radio Telescope was a Kraus-type radio telescope operated by Ohio State University in the USA. Sources claim that it was the size of 3 American football fields, or 726 x 325 hot dogs, proving again that Americans will use anything except the metric system to measure things.

Two metal reflectors faced each other across the huge metal ground plane. They directed radio signals down to a sensor that converted them into printouts.

Scientists at Ohio State University fired up the Big Ear in 1965. The Big Ear would scour the sky for radio signals of all kinds. In 1970, they shifted focus to a dedicated search for radio signals originating from non-human intelligences.

The Big Ear was torn down in 1998.

The Signal

Space is full of radio signals. The Earth is covered in them, too. Most things in space give off radio signals, it seems. We rely heavily on radio technology to run our communication devices. All of that usually creates a blanket of noise that can easily be identified.

On August 15 a signal slammed into the Big Ear Radio Telescope. The signal was the strongest and clearest signal the telescope would ever receive. It was a directed radio blast lasting 72 seconds. Nothing quite like it has ever been detected since.

Jerry Ehman discovered the signal while poring over the mountain of data produced by the Big Ear Radio Telescope. He was so impressed by the data that he circled it in red pen, and famously wrote Wow! next to it.

Starting off low, the signal spiked in strength before dropping off again. It was also only picked up on 1 of the 50 radio channels used by the Big Ear. Here's a quote from Ehman himself:

“It was a narrowband signal, just what we were looking for. It didn't take long for me to recognize that this was extremely interesting. And the word ‘Wow!’ came to my mind very quickly, so I wrote it down.”

The astronomers in Ohio were over the moon. What Ehman had found was exactly the sort of thing that they would have expected to see from an extraterrestrial broadcast. They tried to find the signal again, but after exhaustive attempts, they came up with nothing.

So Aliens for Sure?

Unfortunately the Wow! signal may not be actual proof of aliens communicating with us. Don't get me wrong, it could be aliens, but we'll never really know. Like any mystery worth its salt, this one will never truly be solved. Everyone's got a theory, though.

Seth Shostak, a modern radio astronomer working at SETI, doesn't think the signal was all that special. He claims that such anomalous signals were quite common in the early days. Radio telescopes collected data passively, and a technician would come by every few days to analyze the data and reset the telescope.

Modern telescopes are hooked up to powerful computers that can alert astronomers to exciting data in real time. They can instantly scan the patch of sky for more signals. Unfortunately, that was far beyond the Big Ear Radio Telescope's capabilities.

Shostak said this about people's obsession with the Wow! signal:

“I get emails at least once a month from people who look at that printout and interpret those data in all sorts of ways. People often see it as an alien code that’s being sent as a direct message to humans. They don’t realize the combination of numbers and letters on the printout was just a convention set by astronomers working at the observatory. The printouts couldn’t handle numbers larger than nine, so the display cycles through letters, starting with “B,” for each increasing order of intensity.
“People think they’ve figured out what the message is or how big the aliens are, and it's like a dozen numbers, and all that printout does is give you the level of intensity.”


Aliens beaming down messages to our humble little planet is definitely one idea. People really want to make contact with some outside intelligence. Whether they long for an outside savior to resolve our problems, or a conquering army to rally against, the risk exists to see messages where there are none.

Astronomers have come up with several theories to explain the Wow! signal over the years. One such theory is that the Big Ear picked up an energy emission from a black hole. That's right, black holes don't only suck, they spit too.

Another theory is that the radio signal could have come from closer to home. Antonio Paris of St. Petersburg College in Florida, USA, think comets are to blame. He noticed that around the time that the Wow! signal was detected, two comets were in the area of the sky from whence the signal came.

Paris crowdfunded a project to test out his theory in 2018. Using a radio telescope, his team observed that one of the two comets emitted a radio signal that matched the Wow! signal.

While it isn't proof positive that this comet was responsible, it does indicate strongly that the Wow! signal was a natural phenomenon. You can read his paper here.



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