Play Live Radio
Next Up:
0:00 0:00
Available On Air Stations

Scientists Looking For Alien Life Investigate 'Interesting' Signal From Space

Radio telescopes of the Allen Telescope Array are seen in Hat Creek, Calif.
Ben Margot
Radio telescopes of the Allen Telescope Array are seen in Hat Creek, Calif.

They aren't saying it's alien, but they are saying it's "interesting."

The SETI Institute — the private organization that looks for signals of extraterrestrial life — has announced that it is investigating reports of an unusual radio signal picked up by Russian astronomers.

The signal was detected on a much wider bandwidth than the SETI Institute uses in its searches, and the strength of the received signal was "weak," SETI Institute astronomer Seth Shostak wrote in a blog post.

It was unusual, both in its design and its "beam shape," he says.

The signal might be coming from a solar system called HD 164595, some 94 light-years away from us, Shostak wrote. It seems to be coming from that direction, at any rate.

That system has a star similar to our sun. There's one known planet circling that star, about the size of Neptune and very close to the star. That planet doesn't seem like a good candidate for hosting life, but other planets might also be in the system, Shostak wrote.

But there's no guarantee that the signal is, in fact, coming from the system. And even if it is, that doesn't mean it's definitely coming from intelligent life-forms.

Astronomer Nick Suntzeff told Ars Technica that there's a "significant chance" it could be military — that is, coming from covert satellite communications instead of beaming to us from HD 164595.

And there are "natural sources" that could conceivably cause a wide-band signal like the one detected, Shostak told GeekWire.

Even the astronomers who first detected the signal, in May 2015, didn't immediately alert the scientific community and ask for help confirming the signal. That suggests they were not persuaded this was extraterrestrial life reaching out, he says.

And Shostak wrote on SETI's site that it's "not terribly promising" that this is a message from alien life-forms.

To put things in perspective, Eric Korpela, an astronomer at Berkeley who is a project scientist for the SETI@home project, notes that there are millions of "potential signals" that have been detected from space, and that this signal was detected only once out of 39 scans. "I was unimpressed," he wrote on a SETI forum.

So now is not the time for either delight or panic, depending on your feelings about encountering alien life-forms.

But it is time for more investigation, Shostak says. The SETI Institute's Allen Telescope Array in California has been turned toward HD 164595 since Sunday evening, looking for a repeat of the signal.

METI International is also using a Panama-based observatory to investigate in that direction, GeekWire reports.

You might remember that in 1977, astronomers detected the "Wow" signal, an odd burst that might, possibly, have been sent by alien life-forms. But it has never been detected again, leaving scientists with little to work with.

If things are different this time around and one of the arrays finds a repeat of the new signal, that would "immediately spur" follow-up research, Shostak writes.

In the meantime, it has prompted speculation.

Again, astronomers are cautioning that this might easily be a false alarm. But if the signal were sent from alien life in the HD 164595 system, what would that mean? There are two primary options, Shostak says.

One scenario is that the life-forms sent a powerful signal in all directions — a "here I am" sent to the universe in general. To reach us at its current strength, that would mean the planet had access to 100 billion billion watts of energy, "hundreds of times more energy than all the sunlight falling on Earth," Shostak wrote, indicating a very advanced alien society, with capabilities far beyond ours.

Alternately, the message could have been directed at us. That's a lower energy requirement — about equal to "the total energy consumption of all mankind."

But in that case, they'd have to know we're here. The system is too far away to have picked up any TV or radar from humans on Earth, "and it's hard to understand why anyone would want to target our solar system," Shostak says.

Copyright 2021 NPR. To see more, visit

Camila Flamiano Domonoske covers cars, energy and the future of mobility for NPR's Business Desk.