The 1977 Wow! Signal: Space's most famous mystery could finally be explained

For decades, scientists have scanned the skies, recording an array of radio waves and electromagnetic bursts from deep space. Most have natural explanations, like pulsars, colliding stars, or solar activity. Yet some signals defy understanding. Experts caution that these anomalies could point to intelligent extraterrestrial life and continue to examine them with modern tools alongside decades of astronomical data.

The Wow! signal
In 1977, astronomers detected one of the most famous unexplained signals, the Wow! Signal. Jerry Ehman recorded a 72-second burst so striking that he wrote “Wow!” on the readout. No natural cause has been definitively proven. Recent analyses suggest it may have been a laser-like emission from a dying star interacting with a hydrogen cloud, though extraterrestrial origins remain possible. Dr Hector Socas-Navarro, director of the European Solar Telescope Foundation, told The Daily Mail, "While aliens aren't completely off the table, it seems that the signal may have originated by a natural astrophysical source. Our goal now is to find that source."

Researchers from the Planetary Habitability Laboratory at the University of Puerto Rico are pursuing the Arecibo Wow! Project, re-examining decades of archived SETI data. Abel Méndez said, "Our newly derived properties may help finally pinpoint the source of the Wow! Signal." They aim to archive all Big Ear telescope data by 2027, marking its 50th anniversary.

The team hypothesises that the signal could have resulted from a sudden brightening of hydrogen in interstellar clouds, triggered by a transient radiation source such as a magnetar flare or soft gamma repeater. Méndez added, "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."

ASKAP J1832–0911: A new puzzle
Earlier this year, astronomers identified ASKAP J1832–0911, 14,700 light-years away, emitting radio waves and X-rays every 44 minutes. This long-period transient is the first of its kind observed with X-rays. Experts admit current theories cannot fully explain its behaviour. It might be a magnetar, a dead star with a powerful magnetic field, or an entirely new class of cosmic object.

FRB 20220610A: The fast radio burst
Fast radio bursts are brief, intense flashes of energy from distant galaxies. In 2024, FRB 20220610A was traced to a galaxy cluster eight billion light-years away. Scientists using NASA's Hubble Telescope captured detailed images of the cluster. The origin of these bursts is uncertain, with possible sources including black holes, neutron stars, or even alien civilizations. Brian Lacki, writing in Cambridge's International Journal of Astrobiology, noted that tightly packed galaxies could make interstellar travel easier for advanced life.

K2–18b: Signs of life beyond Earth
K2–18b, 124 light-years away in the constellation Leo, may offer the strongest evidence of extraterrestrial life yet. The James Webb Space Telescope detected dimethyl sulfide and dimethyl disulfide in its atmosphere, molecules linked to microbial activity on Earth. Professor Nikku Madhusudhan from Cambridge's Institute of Astronomy said, "Given everything we know about this planet, a Hycean world with an ocean that is teeming with life is the scenario that best fits the data we have. Decades from now, we may look back at this point in time and recognise it was when the living universe came within reach. This could be the tipping point, where suddenly the fundamental question of whether we're alone in the universe is one we're capable of answering." K2–18b orbits a red dwarf in the habitable zone and is believed to be largely covered in water.

Citizen science and the Wow@Home project
The Wow@Home project allows the public to participate in detecting rare cosmic events. Even small, low-cost telescopes can identify signals similar to the Wow! Signal. Méndez said, "Low-cost systems can operate autonomously around the clock, making them ideal for continuous monitoring of transient events or long-duration signals that professional telescopes cannot commit to observing full-time." The setup costs around $500, with free software provided to connect telescopes to the network and analyse archival data.

This approach not only expands participation in radio astronomy but also increases the chances of discovering new cosmic phenomena and potentially even extraterrestrial technosignatures.