‘It was kind of unbelievable that it was real data,” said Yale University astronomer Tabetha Boyajian. “We were scratching our heads. For any idea that came up there was always something that would argue against it.”
She was talking to the New Scientist about KIC 8462852, a distant star with a very unusual flickering habit. Something was making the star dim drastically every few years, and she wasn’t sure what.
Boyajian wrote up a paper on possible explanations for the star’s behaviour, which was published recently in the Monthly Notes of the Royals Astronomical Society. But she also sent her data to fellow astronomer Jason Wright, a Penn State researcher who helped developed a protocol for seeking signs of unearthly civilisation, wondering what he would make of it.
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To Wright, it looked like the kind of star he and his colleagues had been waiting for. If none of the ordinary reasons for the star’s flux quite seemed to fit, perhaps an extraordinary one was in order.
Aliens. Or, to be more specific, something built by aliens – a “swarm of megastructures,” as he told the Atlantic, likely outfitted with solar panels to collect energy from the star.
“When (Boyajian) showed me the data, I was fascinated by how crazy it looked,” Wright said. “Aliens should always be the very last hypothesis you consider, but this looked like something you would expect an alien civilisation to build.”
KIC 8462852 was discovered through Planet Hunters, a citizen science programme launched at Yale University in 2010. Using data from the Kepler Space Telescope, volunteers sift through records of brightness levels from roughly 150 000 stars beyond our solar system.
Ordinarily, planet hunters are looking for the telltale drops in brightness that happen when a planet crosses in front of its sun. That’s how we identify planets now – brief interruptions in the progress of light as it makes its way toward Earth. Not a presence, but an absence. Already the project has uncovered a few confirmed planets and at least several dozen more planet candidates.
But one finding was unlike anything else scientists had ever seen. Volunteers marked it out as unusual in 2011, right after the programme started: a star whose light curves seemed to dip tremendously at irregular intervals. At one point, about 800 days into the survey, the star’s brightness dropped by 15 percent. Around day 1 500, it dropped by 22 percent. Whatever was causing the dips, it could not have been a planet – even a Jupiter-sized planet, the biggest in our solar system, would only dim this star by 1 percent as it transited across, Slate reported.
The Kepler telescope was badly damaged in 2013, so the researchers don’t have data from more recent dips, if there were any.
Another natural force must be at work here.
In their paper, Boyajian and her colleagues went to great lengths to review and refute the more obvious explanations for the odd display. It wasn’t a mistake, caused by a problem with the telescope or their data processors – they checked their data with the Kepler mission team, and found no problems for nearby stars when they checked their light curves against neighbouring sources.
It wasn’t the star’s fault either. Some young stars, still in the process of accumulating mass, will be surrounded by a whirl of orbiting dust and rock and gas that can blur or block their light.
But this star wasn’t young, Boyajian found.
Nor did it look like other kinds of stars that demonstrate this light variability.
Something must be blocking the star’s light from the outside, the paper concluded – maybe catastrophic crashes in the asteroid belt, maybe a giant collision in the planetary system that spewed debris into the solar system, maybe small proto-planets shrouded in a cloud of dust. But every explanation was lacking in some way, with the exception of one: perhaps a family of comets orbiting KIC 8462852 had been disturbed by the passage of another nearby star. That would have sent chunks of ice and rock flying inwards, explaining both the dips and their irregularity.
It would be “an extraordinary coincidence,” as the Atlantic put it, for that to have happened at the right moment for humans to catch it on a telescope that’s only been aloft since 2009. “That’s a narrow band of time, cosmically speaking.”
Boyajian’s paper only looks at “natural” explanations for the phenomenon, she told the Atlantic. But she’s open to looking at unnatural ones, which is where Wright and his “swarm of megastructures” theory come in.
Scientists have long said that an advanced alien civilisation would be marked by its ability to harness the energy from its sun. They envision something like a Dyson Sphere, a hypothetical megastructure first proposed by physicist Freeman Dyson that would orbit or even encompass a star, capturing its power and putting it to use.
Obviously, a Dyson sphere has never been spotted, though they’re all over science fiction. But if one were to exist, it wouldn’t look like a metal ball around the sun – it would probably comprise a chain of smaller satellites or space habitats, something that would block its star’s light as irregularly as the light of KIC 8462852 has been blocked. That’s why researchers who are interested in finding alien life are so excited about the finding.
Boyajian, Wright and Andrew Siemion, the director of the Search for Extraterrestrial Intelligence Research Centre at the University of California, Berkeley, are now working on getting access to the massive radio dishes they can point at the star in search of the kinds of radio waves usually emitted by technology.
Of course, the star in question is about 1 481 light-years away from Earth – meaning that even if aliens did create a giant solar panel complex, they did so in the 6th century.
Quite a bit has changed on Earth since then. Who knows what could have happened around KIC 8462852? – Washington Post