For more than 50 years, we’ve been scanning the skies with king-size antennas, hoping to pick up a radio signal from space that would prove the existence of other technically adept beings. So far, our efforts have found only senseless static – it’s been a long fishing expedition without so much as a nibble.

However, today there are people who believe that someone is tugging on the line. They suggest that the peculiar behavior of a nondescript star 8,000 trillion miles away could be tipping us off to a massive alien construction project.



That’s an exciting prospect, and not entirely fanciful. After all, tens of billions of biology-friendly planets speckle our galaxy. Surely at least some of those worlds house intelligent beings. If not, then Earth is a miracle, an explanation of last resort for science.



The star in question bears the unsentimental name, KIC 8462852, although is more colloquially know as Tabby’s star in a nod to the Yale University astronomer, Tabetha Boyajian, who led the team that discovered its strange behavior. Tabby’s star was observed by Nasa’s Kepler space telescope, and– thanks largely to the work of astronomy enthusiasts – was found to be a very erratic light source.



Over the course of days, this star can dim by more than 20%, something that ordinary stars never do. Then it will brighten, followed by a relapse of darkening weeks or months later. The amount of dimming is variable, and doesn’t occur with the regular cadence that would mark the presence of an orbiting planet.



When this odd behavior was first recognized, several possible explanations were offered by Boyajian’s team. The most favored was the presence of large clouds of dust from disintegrated comets around Tabby’s star. The orbiting detritus would occasionally mask its light.

But a more intriguing explanation was also proffered: perhaps this star shelters a planet boasting a civilization older and more technically adept than our own. And perhaps these advanced beings have embarked on a massive engineering project, building phalanxes of orbiting solar panels to supply the energy needs of their society. This space-borne construction could cause the dimming.



This idea is so appealing, it has convinced some that an alien megastructure not only accounts for this star’s eccentricities, but also constitutes the first credible evidence for extraterrestrials. This thesis was first broached by Pennsylvania State University astronomer Jason Wright, and was quickly picked up by an enthusiastic space media.

However, before alerting the United Federation of Planets, consider the historical record. Just about every time astronomers have found mysterious behavior in the skies, someone has claimed it’s the work of aliens.

In the 1960s, Cambridge astronomers found puzzling radio pulses coming from our galaxy – pulses as regular as the best clocks. They half-seriously suggested that these might be due to LGMs, or Little Green Men. In fact, they were natural signals from dead stars. At about the same time, some Russian astronomers noted erratic radio transmissions from distant galaxies, which they also dared to propose were caused by aliens trying to get in touch. In fact, they were just giant black holes doing their thing.



There are other examples, but the lesson of history is manifest: if you give aliens the credit for strange phenomena, you’re probably wrong.



Still, skepticism shouldn’t yield to cynicism. After all, the premise that someone is out there is supported by many scientists, and no reasonable evidence should be ignored. In the case of Tabby’s star, there are also new clues. A recent analysis of Kepler data by astronomers Ben Montet and Joshua Simon has shown that this object can slowly, and unevenly, fade over the course of just a few years. Again, this is not standard operating practice for stars. It also makes explanations of Tabby’s star based on either pulverized comets or ambitious aliens trickier.



The bottom line is that, at present, we still don’t know what’s going on in this star system. The safe bet, resting on precedent, is that we are witnessing a perfectly natural phenomenon; one that we don’t yet understand but will eventually fathom. The universe has shown itself to be endlessly creative in creating puzzles for our delectation and bafflement.

But there remains the chance that this is, indeed, something other than a work of unthinking Nature. And while the odds against Tabby’s star being a deliberate construction are long, so are the odds that the cosmic ocean is entirely sterile. So we’ll continue to cast our line into its murky depths.