What is the Wow! Signal and could it have been sent from 3I/Atlas? Scientists revisit the 1977 mystery

Since its discovery in 1977, the Wow! Signal has puzzled radio astronomers. The Ohio State University Big Ear radio telescope found this powerful 72-second narrowband radio signal. The signal was unusually precise at 1420.406 MHz, the hydrogen line frequency used in interstellar communication. Astronomer Jerry Ehman was so impressed by the anomaly that he wrote “Wow!” next to the printout, coining the signal's name.

Despite repeated attempts, the Wow! Signal's origin has eluded researchers for decades. Various theories have been proposed for this unexplained phenomenon, from natural cosmic events to extraterrestrial transmission. New theory suggests a link between Wow! Signal and 2017 interstellar object 3I/Atlas. The possibility that the signal came from this object has revived interest in the 1977 mystery. It raised new questions about the signal and alien contact.

The Wow! Signal: Exploring the possibilities regarding the mystery 

The Wow! Signal is one of the mysterious phenomena in the history of radio astronomy. On August 15, 1977, astronomers at Ohio State University's Big Ear radio telescope detected an intense, narrowband radio signal that lasted for 72 seconds. This new theory offers fresh insights into one of the most enduring mysteries of radio astronomy. The signal was so unusual that astronomer Jerry Ehman wrote "Wow!" next to the printout.

The Wow! signal's frequency was 1420.406 MHz, the hydrogen line's natural radiation frequency. This frequency is important because hydrogen is the most abundant element in the universe and radio astronomy uses it to detect signals from deep space. It appeared to come from Sagittarius. But it has no known celestial body that could explain such a powerful radio burst.

Scientists' theory about the Wow! Signal

Many theories have been proposed about the Wow! Signal, but none have been proven. A cosmic event involving a magnetar or soft gamma repeater may have caused the signal, according to some scientists. These energetic events, which involve bursts of radiation from highly magnetized neutron stars, may have produced a Wow! Signal-like signal.

Researchers have also considered satellite or spacecraft interference as a cause of the signal. Despite careful analysis, radio interference was not a likely explanation because the signal was very different from typical man-made signals.

Avi Loeb's theory that the Wow! Signal is from an extraterrestrial civilization is intriguing. The narrowband signal's focused and precise transmission led some astronomers to suspect an intentional signal at Earth. This theory seems speculative because the signal was never detected again and no other extraterrestrial transmissions have been found.

As stated by Space.com on August 27, 2025, recently, a theory links the Wow! Signal to 3I/Atlas, which passed through our solar system in 2017. Researchers found that the Wow! Signal and 3I/Atlas appear to come from the same sky direction. This theory faces several challenges, including the vast distance between Earth and 3I/Atlas (about 600 astronomical units in 1977) and the power needed to send a detectable signal over such a distance.

Abel Méndez, a researcher from Planetary Habitability Laboratory at the University of Puerto Rico at Arecibo, stated to Space.com,

"Our newly derived properties may help finally pinpoint the source of the Wow! Signal. We also discovered new properties that we look forward to sharing in an upcoming paper. We aim to archive and share all data from the Big Ear telescope by 2027, marking the 50th anniversary of the Wow! Signal."

He further mentioned,

"Our results don't solve the mystery of the Wow! Signal. But they give us the clearest picture yet of what it was and where it came from. This new precision allows us to target future observations more effectively than ever before."

Despite ongoing investigations and reanalysis of old data, the Wow! Signal's origin remains unknown. Scientists at the University of Puerto Rico's Arecibo Wow! Project reexamined archival data to find new clues to the mystery. They have been refining the signal's properties and investigating whether it was caused by a natural astrophysical event rather than extraterrestrial intelligence.