The Wow! Signal: A Mysterious Message from Outer Space Have you ever wondered if we are alone in the universe?
If there are other intelligent beings out there, how would they communicate with us? And what if they already did, but we missed it?
In this article, we will explore one of the most intriguing and controversial events in the history of the search for extraterrestrial intelligence (SETI): the Wow! signal.
What is the Wow! signal?
The Wow! signal was a strong narrowband radio signal detected on August 15, 1977, by Ohio State University’s Big Ear radio telescope in the United States, then used to support the search for extraterrestrial intelligence. The signal appeared to come from the direction of the constellation Sagittarius and bore the expected hallmarks of extraterrestrial origin.
Astronomer Jerry R. Ehman discovered the anomaly a few days later while reviewing the recorded data. He was so impressed by the result that he circled on the computer printout the reading of the signal’s intensity, “6EQUJ5”, and wrote the comment “Wow!” beside it, leading to the event’s widely used name.
The entire signal sequence lasted for the full 72-second window during which Big Ear was able to observe it, but has not been detected since, despite several subsequent attempts by Ehman and others. Many hypotheses have been advanced on the origin of the emission, including natural and human-made sources, but none of them adequately explain the signal. Although the Wow! signal had no detectable modulation —a technique used to transmit information over radio waves—it remains the strongest candidate for an extraterrestrial radio transmission ever detected.
Why is it important?
The Wow! signal is important for several reasons. First, it was detected at a frequency of 1420 megahertz (21-centimeter spectral line), which is naturally emitted by hydrogen, the most common element in the universe and therefore likely familiar to all technologically advanced civilizations . This frequency was also suggested by Cornell University physicists Philip Morrison and Giuseppe Cocconi in a 1959 paper as a possible channel for interstellar communication.
Second, it was very powerful and narrowband, meaning that it had a high signal-to-noise ratio and a small bandwidth. This implies that it was not a random noise or interference, but a deliberate and focused transmission12. The intensity of the signal varied over time, following a Gaussian curve that matched the expected behavior of a fixed source moving across the sky due to Earth’s rotation.
Third, it was never repeated or confirmed by other observatories, making it a unique and mysterious event. If it was indeed an alien message, why did they send it only once? And why did they not include any information or modulation in it? Or maybe they did, but we failed to decode it? These questions have puzzled astronomers and SETI enthusiasts for decades.
What are some possible explanations?
There are many possible explanations for the Wow! signal, but none of them are conclusive or satisfactory. Here are some of them:
● A natural source: Some have suggested that the signal could have been caused by a natural phenomenon, such as a pulsar, a quasar, a hydrogen cloud or a comet. However, none of these sources match the characteristics of the signal in terms of frequency, intensity, duration or location. For example, in 2017, astronomer Antonio Paris proposed that the signal was generated by a hydrogen cloud accompanying Comet 266P/Christensen or P/2008 Y2 (Gibbs), which were passing through the region of interest at that time. However, this hypothesis was criticized by other experts who pointed out that comets do not emit narrowband signals at such high frequencies and intensities.
● A human-made source: Another possibility is that the signal was generated by a human-made source, such as a satellite, a spacecraft or a military experiment. However, none of these sources were known to operate at that frequency or location at that time. Moreover, if it was a terrestrial source, it would have been detected by other radio telescopes around the world.
● An extraterrestrial source: The most exciting and controversial explanation is that the signal was sent by an alien civilization trying to contact us or announce their presence. However, this hypothesis raises many questions and challenges. Why did they choose that frequency and not another one? Why did they send only one signal and not more? Why did they not include any information or modulation in it? How far away are they and how advanced are they? And most importantly, how can we verify their existence and communicate with them? These questions remain unanswered until today.
Conclusion
The Wow! signal is one of the most fascinating and mysterious events in the history of SETI. It could be either a natural phenomenon, a human-made interference or an alien message. However, none of these explanations are convincing or definitive. The only way to solve this mystery is to detect more signals like it or find other evidence of extraterrestrial intelligence. Until then, we can only speculate and wonder about what really happened on that night in 1977.
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