The mystery of the "Wow! signal" has fascinated scientists for nearly 50 years. Now, researchers in Puerto Rico believe they have finally solved it.
Big Ear Radio Observatory and North American AstroPhysical ObservatoryA computer printout with astronomer Jerry Ehman’s exclamation “Wow!” next to the detected signal.
In 1977, a volunteer astronomer at the Big Ear Radio Observatory at Ohio State University was poring over printouts of data collected by the telescope when he discovered something incredible.
The telescope had recorded a shockingly intense, 72-second-long signal coming from deep space. In the years since, scientists have puzzled over what might have caused the anomalous “Wow! signal,” with some speculating that it could have been an alien transmission.
Now, research headed by Abel Méndez from the University of Puerto Rico at Arecibo has presented the most convincing explanation for the mysterious signal yet — and it doesn’t involve aliens.
The Wow! Signal Shocks Astronomers
Ohio State University Radio Observatory and North American AstroPhysical Observatory.The Big Ear Radio Telescope at Ohio State University.
In the 1950s, Ohio State University built a large observatory to use in its Search for Extraterrestrial Intelligence (SETI), a program designed to search the skies for anomalies that might point to alien life. Known as the Big Ear, the telescope was first turned on in 1963. It was larger than three football fields and had the extreme sensitivity to pick up small sounds from space.
In 1977, the SETI program made headlines when a volunteer at the observatory, astronomer Jerry Ehman, noticed an unusually strong signal detected on Aug. 15, 1977. The signal lasted just 72 seconds, and was so extraordinary that Ehman circled the data in red and wrote “Wow!” in the margins.
Next Future FilmsAstronomer Jerry Ehman in the documentary Wow Signal (2017).
What he had discovered was an unusually powerful narrowband radio signal near the hydrogen line. In the years since, scientists have struggled to determine just what might have caused it.
Now, a recent study has come the closest to explaining the truth behind the mysterious Wow! signal.
A New Study Points To Possible Origins Of The Wow! Signal
In recent months, team of researchers led by astrophysicist Abel Méndez from the University of Puerto Rico at Arecibo has been working to solve the Wow! signal mystery.
The team examined archival data collected by the former Arecibo Observatory in Puerto Rico between 2017 and 2020 and soon observed several signals that bore a remarkable similarity to the Wow! signal — though they were notably weaker.
These signals were recorded from interstellar cold hydrogen clouds.
“We report the detection of narrowband signals (10 kHz) near the hydrogen line similar to the Wow! signal, although two-orders of magnitude less intense and in multiple locations,” the researchers wrote. “Despite the similarities, these signals are easily identifiable as due to interstellar clouds of cold hydrogen (HI) in the galaxy. We hypothesize that the Wow! signal was caused by sudden brightening from stimulated emission of the hydrogen line due to a strong transient radiation source, such as a magnetar flare or a soft gamma repeater (SGR).”
Knee & Brunt (2001)Measurements of a cold hydrogen cloud in the outer areas of the Milky Way Galaxy.
Ironically, the research team did not initially seek to explain the origins of the Wow! signal. The team had collected data for years before they realized their findings could reveal important information about one of the biggest mysteries in astrophysics.
“I have to confess, the Wow! signal for me, and for many astronomers, was something like a fluke,” Méndez told Gizmodo. “So I never really paid attention to it.”
It wasn’t until May 2024, when Méndez stumbled upon a video of the Wow! signal online, that he became interested in the mystery.
“I thought, well that would be something amazing to find in our data,” Méndez said.
Given that the signals in Méndez’s data were less intense than the Wow! signal, the researchers believe the Wow! signal could have been caused by a rare event in which a hydrogen cloud is suddenly stimulated by some strong radiation source, like a magnetar — a neutron star with particularly strong magnetic fields. These magnetic fields could excite the hydrogen atoms, causing the interstellar clouds to suddenly brighten.
“That’s rare,” Méndez said. “What’s the chance of a magnetar being right behind one of those clouds, and have strong enough radiation to excite that cloud, and for someone to be looking in that direction at the same time?”
Currently, Méndez and his team are exploring this theory at the Very Large Telescope in Chile, where they will hopefully put an end to the mystery of the Wow! signal once and for all.
After reading about the Wow! signal, dive into the story of Sally Ride, the first American woman in space. Then, read about Starfish Prime, the U.S. operation that involved detonating a nuclear bomb in space.
