How Astronomers Will Determine If That 'Megastructure' Really Is Alien

Astronomers are well on their way to finding out whether the bizarre star KIC 8462852 is the home sun of a technologically-advanced alien civilization.

The star has been the subject of intense media speculation over the last few weeks due to a recent study entitled "Where's the Flux?," which describes its odd light fluctuations. It seems that every 750 days or so, a huge swarm of objects obscures roughly 20 percent of KIC 8462852's light from our perspective.

While the authors provide a wide range of natural explanations for the odd dips in the star's luminosity, astronomers involved in the study, as well as outside observers, are not ruling out that the star might be periodically eclipsed by an alien megastructure. For instance, perhaps the star is periodically dimmed by a Dyson sphere crafted from solar panel satellites orbiting the star in tight formation.

"The chances are pretty high that what this is something completely natural," said Seth Shostak, senior astronomer and director of the Search for Extraterrestrial Intelligence (SETI) Institute, in a phone interview with Motherboard.

"But on the other hand, you don't just blow it off," he continued. "If you don't check it out, you can't be sure. In fact, even if you do check it out, you can't be sure."

With that said, we can make an educated guess about the structures by taking a closer look at the star. SETI is currently using the Allen Telescope Array (ATA) northeast of San Francisco to hone in on the star's radio emissions, between the frequencies from 1 to 10 gigahertz. The goal is to pinpoint any strong signals within an unusually tight band of the radio spectrum, much like the WOW! Signal, which was received by SETI in 1977 and remains unexplained to this day.

"If you look at as much of the radio dial as possible, you can see if there's any radio noise at a given spot on the dial," he said. "Natural noise is all over the dial […] but there's nothing in nature that we know about that produces lots of radio noise just at a very narrow range of frequencies."

This kind of narrow band signal, if discovered, would be substantial evidence that intelligent life is thriving in the KIC 8462852 system—or at least, that it was 1,480 years ago, when the light first started traversing the 1,480 lightyear distance between the star and Earth.

Indeed, the very feat of transmitting such a strong signal would require engineering capabilities that boggle the mind.

"This star is 1,480 light years away," Shostak pointed out. "That's about 300 times farther than the nearest stars. Any signals [from that distance] are 100,000 times weaker, and that's a big factor. Even assuming that there is anybody there, they would have to have either a really hunky transmitter, for you to be able to hear it at that distance, or it would have to be deliberately focused in our direction."

"Having said that, if you have a Dyson swarm that can intercept 20 percent of the light from your star, that's a trillion times more energy than you'd need for this transmitter. So maybe energy is pretty cheap for these guys."

Primer on Dyson spheres. Video: SciShow/YouTube

Indeed, Shostak and his colleagues at SETI will also be looking for less rigid anomalies in the radio spectrum, such as the radio noise that might be emitted by, let's say, super-powerful rockets sent to service the hypothetical solar swarm. "It would take a heck of a large rocket to make enough radio noise that you could pick it up from the distance of this star, but it's not impossible," he said.

All told, it will only be a few weeks before the ATA has a solid read on KIC 8462852's emissions, so we may know whether or not we have new radio penpals by Thanksgiving.

But other teams interested in investigating the source of star's light fluctuations will have to hold out longer before they can confirm the existence of aliens one way or the other.

For instance, Penn State astronomer Jason Wright, one of the first scientists to suggest these dips might be technological in origin, is leading an effort to examine the composition of the occulting materials. But to do so, Wright's team will have to wait until the bulky swarm passes in front of the star again, producing what's called a "deep event," before they can analyze its chemical makeup.

"We'll be trying to determine the composition of the obscuring material the next time a deep event occurs," Wright told me over email. "We might be waiting a while (the first deep event occurred in Kepler's third year of operation)."

Whenever it does happen, the research "will be very diagnostic," he said. "If the obscuring material is gas or dust, we'll be able to tell right away."

In the meantime, Wright hopes to probe the system for more salient specifics, such as whether or not the star hosts planets. However, given how far away this star is, finding planets around it will be an uphill battle. "This star is not amenable to most forms of planet detection," he told me. "We'll do our best, though."

Regardless of whether the dips in brightness are shaped by aliens, rogue comets, smashed planets, or any of the other numerous theories regarding its behavior, KIC 8462852 is undeniably one odd stellar duck. Nothing else is like it in the skies. Aliens or no, that is more than enough reason to take a closer look at this tantalizing system.