For nearly half a century, astronomers have been puzzled by a brief and unexplainable radio signal detected in 1977 that seemed to hint at the existence of alien life. Known as the “Wow! Signal,” this tantalizing cosmic transmission has remained one of the most intriguing mysteries in the search for signs of intelligent life in outer space. Now, scientists may finally know where it came from!
A team of researchers may have uncovered a potential astrophysical explanation for the Wow! Signal that could reshape our understanding of this enduring enigma. Their findings, currently published in the preprint journal arXiv, suggest the signal may have been the result of a rare and dramatic event involving a burst of energy from a celestial object interacting with clouds of cold hydrogen gas in the Milky Way galaxy.
“Our latest observations, made between February and May 2020, have revealed similar narrowband signals near the hydrogen line, though less intense than the original Wow! Signal,” explains Abel Méndez, lead author of the study from the Planetary Habitability Laboratory at the University of Puerto Rico at Arecibo, in a media release.
“Our study suggests that the Wow! Signal was likely the first recorded instance of maser-like emission of the hydrogen line.”
The Wow! Signal was detected by the Big Ear radio telescope at The Ohio State University on August 15, 1977. It exhibited several intriguing characteristics, including a narrow bandwidth, high signal strength, and a frequency tantalizingly close to the natural radio emission of neutral hydrogen — an element abundant throughout the universe. These properties led many to speculate the signal could be of artificial origin, perhaps a deliberate message from an extraterrestrial intelligence.
This passing burst of activity in space led Dr. Jerry Ehman to famously write “Wow!” next to the print-out of the signal, which was like nothing else astronomers were seeing in space at the time. However, the signal was never detected again, despite numerous attempts to locate its source over the ensuing decades.
This has posed a major challenge for the SETI (Search for Extraterrestrial Intelligence) community, as repetition is considered essential for verifying the authenticity of a potential extraterrestrial signal — also known as a technosignature.
This new study, however, is pushing the conversation away from an alien radio transmission and closer to a once-in-a-lifetime natural occurrence in deep space. The researchers’ key insight stems from observations made using the now-decommissioned Arecibo Observatory in Puerto Rico, one of the world’s most powerful radio telescopes until its collapse in 2020.
For now, the Wow! Signal remains shrouded in mystery, but there is now at least a plausible explanation for its existence — one that does not involve aliens.