That “Strong” SETI Signal Probably Isn’t Aliens

Sorry folks, E.T. is still not phoning home

radio telescope
The Ratan-600 radio telescope, which reported the signal to the SETI Institute александр с кавказа via Wikimedia Commons

This week, a group of  astronomers picked up a radio signal that was emanating from a distant star and reported the find to the Search for Extraterrestrial Intelligence (SETI) Institute. The announcement sparked speculation that it may have been broadcast by aliens. As is often the case with the SETI signals, however, the reality of possible extraterrestrial origins of the radio waves is a bit more tame than many would like to believe.

Back in May 2015, researchers operating out of the RATAN-600 radio telescope in Zelenchukskaya, Russia were conducting a survey of stars, according to a SETI press release. After combing through the data, they recently discovered that the telescope had picked up a signal that appeared to have emanated from a solar system 94 light-years away called HD 164695. Scientists have known about this distant solar system for years. It’s a few billion years older than our own and even has a Neptune-like gas giant orbiting a sun-like star. However reports suggesting this radio signal was broadcast by an advanced alien civilization are stretching it a bit too far, says astronomer Yvette Cendes, a researcher at the Anton Pannekoek Institute at the University of Amsterdam.

“There’s a lot of things that go bump in the night, but immediately saying it’s aliens? We’re nowhere near that point,” Cendes tells

What’s strange about this report isn’t that the astronomers detected a radio signal—that happens fairly often. When astronomers use radio telescopes to scan the skies, they can pick up strange signals produced by common phenomena, such as stellar flares or the last gasp of a star being consumed by a black hole. Not to mention the wide variety of man-made radio signals that often make their way back to astronomers’ telescopes.

“Satellites give off a lot of stuff, we see radio signals bounce off meteors,” Cendes says. “I’ve seen a lot of man made signals in the sky, let’s put it that way.”

There are other reasons to question the finding. First of all, the RATAN-600 has an odd design compared to other radio telescopes: It is made up of a large ring embedded in the ground, according to SETI. As a result, the portion of the sky that it captures is shaped differently from other telescopes, which could result in some distortion. Secondly, contrary to some reports, the signal was fairly weak when compared to SETI's other recorded pulses.

“I wouldn’t call it a super bright signal,” Cendes says. “It’s decent enough you’re going to see it, but it’s not the brightest thing in the sky. It’s not even in the top ten. You would see it, but it wouldn’t be eye popping.”

In order to confirm that a radio signal is from an alien civilization, astronomers would need to verify it with a second telescope. But because the reported came in more than a year after it was detected, it's a lot harder to double check. While several radio telescope arrays have since been pointed in HD 164695’s direction, no one else has yet found a repeating signal. So far, the only thing anyone can really say about this signal is that it was a radio signal detected by astronomers.

“If you hear hooves, don’t say zebras,” Cendes says. “You shouldn’t first think this is a zebra, you should think this is an animal with hooves.”

At the moment, SETI astronomers and most of the scientific community are taking the findings with a pretty large grain of salt. As much as some people want to believe in alien life, this signal is probably not E.T.'s cry for contact.

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