The historic ‘Wow!’ signal may finally have a source. Sorry, it’s not aliens

One between of the predominant compelling potential indicators of extraterrestrial communique may need an astrophysical rationalization.

Acknowledged as the “Wow!” sign, the bright burst of radio waves has defied our know-how keen on that its discovery interior the Seventies. Now, scientists using archived bureaucracy from the Arecibo Observatory in Puerto Rico propose a new manageable source for the sign: a cosmic hydrogen cloud that emitted soft like a laser.

“I imagine we have now gotten perchance the exact rationalization for that rationale a platforms,” says astrobiologist Abel Méndez of the School of Puerto Rico at Arecibo. Méndez, at the identical time with astrophysicist Kevin Ortiz Ceballos of the Harvard and Smithsonian Core for Astrophysics in Cambridge, Mass., and Jorge Zuluaga of the School of Antioquia, Colombia, submitted this belief to arXiv.org on August sixteen.

The unique “Wow!” sign was once detected a long time ago by the Big Ear radio telescope at Ohio Country School. As the telescope scanned the sky, a computing device computing tool software program modified incoming radio indicators to a sequence of letters and numbers representing their intensities and printed it out overnight.

Inner the morning, astronomer Jerry Ehman and his colleagues would seem to be over the printouts for a thing wonderful. When Ehman obvious a sign from the night of August 15, 1977, he clinically determined it as a thing reasonably bright.

Much more positive intriguingly, it was once in a slim wavelength fluctuate linked with neutral hydrogen atoms. Completely diversified astronomers occupied with the seek extraterrestrial intelligence, or SETI, had cautioned this wavelength may correctly be a pure calling frequency for alien civilizations. Ehman circled the sign and wrote “Wow!” interior the margin in crimson pen.

The sign has never been thought of over lower again. Astronomers have cautioned an highly good series of nonalien explanations for the unique, inclusive of comets in our picture voltaic approach and interference from Earth-orbiting satellites or space particles. But none of them completely retailer up.

Wanting out for comparable indicators, Méndez and colleagues sifted by a series of the closing bureaucracy taken by the Arecibo radio telescope in the past it collapsed in 2020 (SN: 12/4/20). Between February and May 2020, Arecibo’s antenna tracked the sky comparable to how the Big Ear had interior the Seventies, letting the researchers compare the bureaucracy devoid of delay.

Méndez wasn’t taking a look ahead to to to notice a whole lot. “I knew about the ‘Wow!’ sign for a protracted time, like everybody. But I disregarded it, perchance like many astronomers, as some fluke,” Méndez says. “No longer an astronomical match. And definitely even a whole lot less, aliens.”

But to his shock, the Arecibo bureaucracy proven an highly good series of indicators that looked a lot like “Wow!” — best dimmer. He realized that the indicators corresponded to clouds of cold atomic hydrogen scattered round the galaxy.

“I reported, ‘Wait, wait, wait!’ That was once the second,” Méndez says. “If it was once brighter for a second, which may be it. Which has to be would becould okay be the ‘Wow!’ sign.”

The following question was once the approach to at this time brighten clouds of hydrogen. The facts nonetheless has to be ironed out, but Méndez and colleagues have an belief: A bright radio source, from a thing like a magnetized useless superstar, a magnetar, should emit a flare and zap the cloud with vigour. That vigour should excite the hydrogen atoms in a selected way and set off a laserlike finish have an effect on, where the entire atoms emit soft interior the equal wavelength at the equal time (SN: 4/23/10).

correctly be an peculiar phenomenon, Méndez admits. Such hydrogen masers have been in-built labs on Earth, but few have been obvious in space, and none at this frequency. One of the proper alignment of a magnetar, a chilly hydrogen cloud and the Big Ear would have been lucky, too — but that would manual supply an evidence for why the sign was once thought of best once.

If this rationalization seems to be good, it should pose a topic for SETI searches (SN: 9/30/18). If astronomers ever notice every other sturdy sign at this frequency, it'd be doubtful even with whether or not it was once from aliens or glowing hydrogen clouds.

“The SETI assignment has been taking a look precisely for the form of match,” Méndez says. “If we have now gotten a pure approach which may produce that, that would correctly be a false good.”

Completely diversified astronomers are reserving judgement unless the facts of the maser finish have an effect on are fleshed out more positive, which Méndez and colleagues plan to do in a note-up paper.

“He’s suggesting a phenomenon that has never been obvious,” says SETI astronomer Jason Wright of Penn Country, who was once not concerned interior the new work. “The set of precise conditions is kind of mild and explicit, and it’s not clear if that’s even manageable.”

But even even with the fact that the “Wow!” sign was once naturally occurring, “which may be cool,” Wright says. “The false positives of SETI can lead to brilliant science.” As an instance, when astronomers first spotted pulsars, they is called the spinning stellar corpses “LGM” for “Little Inexperienced Guys” (SN: three/eight/18). The seminal paper on their discovery committed an whole part to ruling out ET.

“It wasn’t aliens,” Wright says, “nevertheless it with out doubt was once nonetheless a Nobel prize.”