Cosmic 'wow' alien signal mystery solved at last, claim scientists

A mysterious radio signal detected nearly five decades ago and long speculated to be evidence of extraterrestrial life may finally have a natural explanation, according to new research. The so-called Wow! signal was first detected on August 15, 1977 by Ohio State University’s Big Ear radio telescope. Astronomer Jerry Ehman famously wrote “Wow!” on the printout after seeing the unusual 72-second burst, which occurred at 1420 MHz – the frequency of hydrogen, the most common element in the universe.

For years, the origin of the signal has been debated, with theories ranging from comets to space debris to intelligent alien transmissions. But a new study by the Arecibo Wow! Project, published on 14 August 2025 on the preprint server arXiv, suggests the event was the result of a powerful astrophysical flare. Led by planetary astrobiologist Professor Abel Mendez of the University of Puerto Rico, the team re-analysed 75,000 pages of archival data, digitising and refining earlier measurements. Their results suggest the signal was stronger than previously thought – exceeding 250 Janskys – and more narrowly localised within the constellation Sagittarius.

The researchers propose that the event was caused by a flare from a magnetar, a highly magnetised neutron star, which struck a cold interstellar hydrogen cloud. This could have triggered a “maser flare”, a natural amplification of hydrogen emissions similar to a cosmic laser. The team say this explanation accounts for the intensity, narrow bandwidth, and one-off nature of the signal.

The study also rules out terrestrial interference such as satellites, television transmissions, or solar activity, and dismisses earlier suggestions that comets or reflections from space debris were responsible. Observations from the Arecibo telescope in Puerto Rico, before its collapse in 2020, had previously detected weaker emissions from hydrogen clouds consistent with the new theory.

Despite this, some scientists remain cautious. The hydrogen frequency is considered a prime candidate for potential extraterrestrial beacons, and previous researchers – including Big Ear director John Kraus – described the signal as “highly suggestive” of intelligent origin. The possibility of alien involvement cannot be fully ruled out.

Speculation has also been fuelled by the recent discovery of interstellar comet 3I/ATLAS (C/2025 N1), which is currently passing through the solar system from the same general region of Sagittarius. Some researchers have suggested a possible link, though most astronomers argue its observed outgassing and dust tails are typical of comets.

The Wow! signal remains the most famous candidate in the search for extraterrestrial intelligence (SETI), but not the only one. In 2003, astronomers identified a short-lived radio burst known as “SHGb02+14a” during a SETI survey, while more recently unexplained narrowband signals from Proxima Centauri were investigated in 2020 under “Breakthrough Listen”.

All were later found to have likely natural or terrestrial origins, but each underscored the challenges of distinguishing potential alien transmissions from cosmic noise.

Professor Méndez said the new analysis does not close the case, but “reopens it, with a much sharper map.” The team aims to digitise all Big Ear data by 2027, the 50th anniversary of the detection.

Future instruments such as the Square Kilometre Array are expected to provide greater sensitivity and may determine whether the Wow! signal was indeed a rare natural phenomenon – or something more.