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SETI Telescopes Are Investigating a Weird Radio Signal from a Sunlike Star

We all want to believe, but it's probably not aliens saying hello.
Concept art of an alien planet. Image: Pixabay

An unusual radio signal from a Sunlike star has prompted alien hunters to take a closer look at the system, located just 94 light years away.

The 11 gigahertz radio burst, lasting two seconds, was picked up on May 15, 2015 by the RATAN-600 radio telescope in Zelenchukskaya, Russia, and was kept under wraps for well over a year. Until now.

Over the weekend, interstellar spaceflight expert Paul Gilster broke the news that a team led by astronomer Nicolai Bursov of the Special Astrophysical Observatory—and including famed Search for Extraterrestrial Intelligence (SETI) astronomer Claudio Maccone—has been analyzing the signal, and will be presenting findings at the 67th International Astronautical Congress in Guadalajara, Mexico, on September 27.


"No one is claiming that this is the work of an extraterrestrial civilization," Gilster cautioned, "but it is certainly worth further study."

To that end, SETI has trained both its Allen Telescope Array in California and the Boquete Optical SETI Observatory in Panama toward the star, named HD 164595, which is within 100 light years of Earth, in the constellation Hercules—a cosmic stone's throw away.

Adding to the excitement is the star's status as a veritable "solar twin" to our own Sun, differing in mass by only one percent, and "almost identical" in metallicity, according to Gilster. We also know it hosts at least one planet, a hot Neptune-sized world about 16 times more massive than Earth, with a year of 40 days.

Sunlike star with at least one confirmed planet? Check. Near enough to Earth for two-way communication to theoretically take place, albeit over several generations? Check. Strong radio signal at a frequency that is unusual for a natural astronomical source? Triple check. Even the fact that researchers who first recorded the signal kept it a secret smacks of some grand alien-related conspiracy.

Maybe it is. But probably not. False positives are a well-known occupational hazard for alien hunters, as SETI director Seth Shostak eloquently demonstrated in a recent Air & Space article about a "dry run" in 1997.

The enormous RATAN-600 facility that detected the signal in May 2015. Image: александр с кавказа

"The incident demonstrated that any promising signal will become public knowledge immediately, even though it will be days or weeks before it's rigorously confirmed," Shostak pointed out. "While that fact should quiet those who think that any detection of alien intelligence would be kept under wraps to avoid panic among the populace, the corollary is that in the future, you should expect to hear about some signals that look good but, after a few days of checking, don't pan out."


"As soon as an interesting signal tickles a radio telescope, scientists will start tweeting and blogging," he added. "You can bet on it."

This is a prophetic observation in light of the traction that the HD 164595 signal is already gaining around the world. Though the RATAN-600 researchers neglected to communicate their findings to the wider scientific community for several months—a lag time that has some scientists miffed—the cat is now out of the bag. Naturally, stories about how this unbagged cat is definitely an alien from a Kardashev Type II civilization are rife across the internet.

But though the signal is absolutely worthy of further investigation, odds are it has a completely natural explanation. For instance, Jean Schneider, an astronomer based at the Paris Observatory, has proposed that HD 164595 may be intensifying a background radio source via a process called gravitational microlensing, in which powerful gravity fields magnify phenomena behind them from Earth's perspective. Interference from our own radio communication devices has also not been ruled out as a possible source for the signal.

There's nothing wrong with getting excited over weird feedback from outer space. But the frenzy does recall a timeless lesson that Carl Sagan doled out in the fourth episode of Cosmos: A Personal Journey.

Sagan being Sagan. Video: PinkChicken42/YouTube

"I can't see a thing on the surface of Venus," Sagan said, channeling over-eager planetary scientists. "Why not? Because it's covered with a dense layer of clouds. Well, what are clouds made of? Water, of course. Therefore, Venus must have an awful lot of water on it. Therefore, the surface must be wet. Well, if the surface is wet, it's probably a swamp. If there's a swamp, there's ferns. If there's ferns, maybe there's even dinosaurs."

"Observation: You couldn't see a thing," he sums up. "Conclusion: Dinosaurs."

I'm not one to put down any theories about extraterrestrial dinosaurs, but Sagan's point remains relevant to this day. Our tendency to put the cart light years beyond the horse when it comes to anything alien says much more about the human yearning for connection with other intelligent lifeforms than it does about those speculative civilizations.