Impossible Data—the Alien Megastructures Mystery Begins
Astronomer and alien megastructures theorist Tabetha Boyajian knew something wasn’t right. The data she was looking at wasn’t just strange—it was impossible.
She was looking at a star whose official scientific name is KIC 8462852. Actually, she wasn’t looking at the star itself. Dr. Boyajian, an astronomer at Yale University, was looking at the data about the star. The data said that the star was dimming, and not just a little. It was dimming by over 20%, and then returning to normal brightness. Stars don’t do that.
Sure, a type F star like KIC 8462852 might dim for a while, by maybe a percent or two.
Tabby rechecked the data, had others look. It was a colleague, Jason Wright, who came up with a mind-blowing explanation.
Tale of the Two Theories
When Tabby’s Star hit the mainstream, there were two competing ideas about what could be causing such bizarre dimming behavior.
Theory One: alien megastructures. This is what Jason Wright from Pennsylvania State University had suggested to Tabby—some kind of structure might exist around that star that causes it to dim for periods of time. Obviously an idea like that is going to get attention; pseudo-skeptics around the world couldn’t stop themselves from attacking Dr. Wright. Aliens!? They can’t exist! You cannot have found them! It’s impossible because it’s impossible!
Reality check: no one, not Jason, not Tabetha, has suggested that there is any kind of proof of an alien megastructure. But it’s a reasonable explanation for the 20% reduction in light coming from an enormous thermonuclear fusion engine.
Theory Two: comet swarm. For a brief period of time, media pundits were reporting that the mystery was over; it was just some swarming comets in front of the star, dude, so chill out. It’s not aliens.
Dr. Tabby herself was not particularly sold on the idea. “It’s a bit of a stretch to have comets that are large enough to block that much of the light from the star,” she said.
Still, other than these two theories, there have been no reasonable explanations for what is causing Tabby’s Star to dim so radically.
It’s Not Comets
Bradley Schaefer wasn’t trying to add to the controversy. An astronomer at Louisiana State University, he went to look at photographic plates taken of the sky around Tabby’s Star, photos that go back a century, just hoping to help shed light on the mystery.
What he found was stunning and extremely weird: Tabby’s Star has been dimming for decades now. Its brightness has faded by 20%, steadily, since 1890. This is not something that stars are known to do. Not a star in the sky has ever been seen to dim like this, except for one.
So comets are out the window. “The century-long dimming trend requires an estimated 648,000 giant comets … all orchestrated to pass in front of the star within the last century,” wrote Dr. Schaefer. In other words: there’s no way it’s comets.
Radio Silence from Tabby’s Star
When Seth Shostak first caught wind of the bizarre dimming star—and the alien megastructure theory—he sprang into action. Seth is in charge of SETI, the Search for Extraterrestrial Intelligence, and so he commands a huge herd of giant radio telescopes, all listening for signals from alien civilizations. He ordered all of them to be immediately pointed to Tabby’s Star. Why? If there is an intelligent civilization (building alien megastructures!) then we might expect that they’ve generated some radio signals.
Initial reports are that there were no unusual signals coming from that direction. Strangely enough, pseudo-skeptics declared victory: “Odd star’s dimming not aliens’ doing” was the headline from Science News, a magazine with obvious pseudo-skeptical bias. The article provided no explanation of why they could make such a blanket statement—the author confesses that the dimming is not caused by comets, but offers no alternative explanation. Author’s ulterior motive confirmed: it can’t be aliens because it can’t be aliens.
Does it matter if there were no radio signals? Apparently we have extreme confidence that
- the aliens were broadcasting on the radio bands SETI chose to listen on
- we were listening at the right time (the signals arriving at Earth would be 1,500 years old, because of the distance of Tabby’s Star from here)
- the aliens use radio at all.
This isn’t science, it’s hubris. Sure, it was absolutely worthwhile to listen. But getting no immediate evidence doesn’t shut the book on aliens and their megastructure—it only deepens the mystery.
This Is Where We Stand: Alien Megastructures
There is only one viable explanation currently available for the radical dimming of Tabby’s Star: a giant structure enveloping it, causing it to fade periodically. Ever single other idea has been dismissed—debunked, you might say—as an unsatisfactory explanation. It’s not comets, unless (as Dr. Schaefer says) someone orchestrated more than half a million comets to pass in front of the star for over a century.
And just because you don’t want to believe that it’s aliens doesn’t mean that it’s not aliens. Because it’s probably aliens. Sorry if that disappoints your addiction to a mundane and lifeless universe.