The coincidence that is alarming astronomers about the WOW! signal and comet 3I/ATLAS: “The probability of it being random is 0.6%”

In August 1977, at the Big Ear radio telescope in Ohio, astronomer Jerry Ehman was so stunned by a radio signal that he scribbled “WOW!” in the margin of his printout. The signal lasted just 72 seconds and never returned, but it quickly became the holy grail for the Search for Extraterrestrial Intelligence, or SETI.

It came from the constellation Sagittarius, precisely where astronomers were hoping to find something unusual. Even more striking, the signal arrived at 1420 megahertz, the frequency of hydrogen, the universe’s most abundant element. That frequency is reserved for scientific use, no one should be broadcasting there. No one, that is, except someone who wants to be heard.

Ehman later summarized the enigma cautiously: “I cannot say it was an extraterrestrial civilization,” he said. “But I also cannot say it wasn’t.”

For decades, astronomers searched the same area of the sky with better equipment, longer observation times, and more patience. Nothing returned. It was as if the universe had whispered hello and then vanished forever.

Enter 3I/Atlas

Forty-eight years later, on July 1, 2025, the ATLAS system in Chile detected an object coming from deep space. Not an ordinary comet, but an interstellar one, like ‘Oumuamua’ in 2017 and Borisov in 2019. Its speed, hyperbolic trajectory, and chemical composition confirmed it was not from our solar system.

The shocker? It was coming from the same region of the sky as the WOW! signal.

Harvard astrophysicist Avi Loeb ran the numbers. In August 1977, he calculated, 3I/Atlas was about three light-days from Earth and separated from the WOW! signal by only four degrees in right ascension and eight degrees in declination. Loeb estimated the probability of a random coincidence at just 0.6 percent. If the comet was the transmitter, he added, it would have needed between 0.5 and 2 gigawatts of power, roughly the output of a nuclear power plant.

The WOW! signal was observed at 1420.4556 MHz, slightly blue-shifted as if moving toward us at about 6 miles per second, matching the direction 3I/Atlas was traveling toward the Sun. Everything seemed to fit, but how could a comet emit radio waves?

A comet unlike any other

3I/Atlas does not behave like a normal comet. Its tail points toward the Sun instead of away from it. Its composition includes nickel without iron, an alloy typically found in human industrial processes. Its acceleration cannot be fully explained by gravity alone.

NASA scientist Tom Statler expressed both amazement and caution: “It looks like a comet. It acts like a comet. But it also does things no comet should do.”

Oxford astronomer Chris Lintott was blunt: “It’s weird. Really weird.”

Astronomers estimate 3I/Atlas could be as old as 10 billion years, predating our solar system. Its origin likely lies in the Milky Way’s thick disk, home to the galaxy’s oldest stars. NASA’s Davide Farnocchia called it “a time capsule from the birth of the galaxy.”

Remarkably, as it neared the Sun, the comet survived a solar storm without breaking apart, something no known comet has done. Physicist Michio Kaku hinted at the extraordinary: “If it gains additional energy during the flyby, that could indicate extraterrestrial intelligence at work.”

All eyes on 3I/Atlas

So far, no radio telescopes have detected new emissions from 3I/Atlas. But the coincidence with the WOW! signal has reignited debate. NASA, ESA, and more than 200 observatories are tracking its path, while the Mars Reconnaissance Orbiter and the JUICE mission prepare for close observations. Scientists are also reanalyzing the 1977 data from Big Ear with modern tools, hoping to uncover new clues that were previously invisible.

If 3I/Atlas caused the WOW! signal, we might not be alone in the universe. If it didn’t, it is still the strangest comet humanity has ever seen.

Sources

All figures, observations, and quotes come from official sources, including NASA, ESA, ATLAS, and public statements from Avi Loeb, Michio Kaku, Tom Statler, Davide Farnocchia, and Chris Lintott. The link between the WOW! signal and comet 3I/Atlas remains under study, with definitive conclusions dependent on future observations.

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