Updated: 23rd October 2017

Have we detected an alien megastructure in space? Keep an open mind | Seth Shostak

KIC 8462852, aka Tabbys star, shows a pattern of behavior that has perplexed scientists and fascinated amateurs. We still dont know whats causing it

For more than 50 years, weve 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 its 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.

Thats 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 Tabbys star in a nod to the Yale University astronomer, Tabetha Boyajian, who led the team that discovered its strange behavior. Tabbys star was observed by Nasas 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 doesnt 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 Boyajians team. The most favored was the presence of large clouds of dust from disintegrated comets around Tabbys 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 stars 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 its 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, youre probably wrong.

Still, skepticism shouldnt 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 Tabbys 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 Tabbys star based on either pulverized comets or ambitious aliens trickier.

The bottom line is that, at present, we still dont know whats going on in this star system. The safe bet, resting on precedent, is that we are witnessing a perfectly natural phenomenon; one that we dont 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 Tabbys star being a deliberate construction are long, so are the odds that the cosmic ocean is entirely sterile. So well continue to cast our line into its murky depths.

Read more: http://www.theguardian.com/us

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