Why so many alien hunters are looking at this one mysterious star in the sky

Soak up the sun.
Soak up the sun.
Image: Flickr/Kevin Gill under CC-BY
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Alien hunters are abuzz. A mysterious star called KIC 8462852 is their latest hope for finding an intelligent species beyond the Earth. And they are throwing every resource they can to find a way of confirming that aliens exist.

In a study first released online in September, a team of scientists has shown that KIC 8462852 has a mysterious flicker—for its age and type, the star should be much brighter than telescopes show it to be. While the research has not yet been reviewed for publication, it is already stirring up excitement in the scientific community and beyond; after eliminating other theories, some suggest that the only explanation for the flicker is the presence of light-blocking megastructures, built by aliens.

Here are the hypotheses they eliminated: The star could be surrounded by cloud of dust…but it is too old to have such a planet-forming disk. A collision of planets could have caused the formation of a thick layer of debris…but such an event is too brief in cosmological timescales to be spotted by human telescopes. Finally, there could be a swarm of comets creating the shade…but calculations show the dimming is far too much to be explained by comets alone.

All this leaves one theory standing: The star’s light is being partially blocked by a huge solar panel construction.

Soak up the sun

In the 1960s, renowned physicist Freeman Dyson argued that the energy demands of any intelligent race would, within a few millennia using advanced technology, outstrip whatever supply were available on the planet. In that case, the most effective way to start capturing more energy would be to build a solar-panel contraption to capture its star’s light. Such a structure would start small, but in theory eventually cover the whole star, in what is now called a “Dyson sphere.”

Could it be the case that the Kepler space telescope has captured the dimming star while this alien megastructure is under construction?

To investigate this possibility, on Oct. 16, the Institute for the Search for Extraterrestrial Intelligence (SETI), one of the leading organizations in the effort, put its normal surveys of the sky on hold. Its array of 42 antennae are now all pointing at KIC 8462852, hoping to listen to an intelligent radio signal. Billionaire Yuri Milner donated $100 million to SETI earlier this year in anticipation of just such an opportunity.

In normal surveys, SETI looks at a narrow band of microwave radiation that is considered to carry most likely signs of an intelligent race. But in this case, with more “eyes” looking at the same place, SETI has expanded its data collection to a larger band of radiation.

Then, on Oct. 20, the American Association of Variable Star Observers (AAVSO) issued a notice to its amateur astronomers to focus on KIC 8462852. Although it’s only a hobby for the thousands of volunteers on AAVSO’s list, such hobbyists have made significant discoveries in the past.


But the likelihood that flickering light is due to alien structures is very low, according to Anders Sandberg, a futurist at the University of Oxford.

Sandberg believes that the hypothetical window of opportunity between when aliens start building a Dyson sphere and when they finish it—engulfing the star and making it invisible to our telescopes—could be as little as a few centuries, which is quite small on cosmological timescales. By his estimate, human’s chance of ever observing KIC 8462852 with a partially built Dyson sphere is one in four million.

Another possibility is that there is a Dyson sphere around this mysterious star, but it is already built and in the course of decay. This could happen if the intelligent race that built it died out, or found a way to abandon the star and go to another one. Such a decay could take perhaps hundreds of thousands of years, a bigger window than when the Dyson sphere is being built—but the chances of observing such a phenomenon remain rare.

How to find aliens

As with any alien hunt, there are other crazy hypotheses—arc mirrors that make stellar engines, sorting asteroids with solar radiation, or climate engineering with solar shades—all less likely than a Dyson sphere.

But in the end, it might just be that the dimming is explained by a yet-unknown cosmological phenomenon. Jon Jenkins from the team that runs the Kepler telescope says, “It’s not unusual for new phenomena to be greeted with an explanation calling for extraterrestrials that later prove to be due to more mundane but novel natural phenomena.”

In the 1960s, for instance, a weird phenomenon made astronomers name a star LGM-1 (after little green men). But it turned out that the star was a pulsar. Since then 1,800 pulsars have been found and the little-green-men hypothesis ruled out.

For 60 years at least, humans have put in consistent effort to look for aliens without success. Still, optimistic scientists console us by showing equations that reveal the chances of us being alone in the universe are quite low. And they have good reasons for why at least some of us should keep looking.

If it turns out that there are no intelligent species apart from us, then human are either extremely unusual, or the universe’s other intelligent species have all died out—and we are likely to, too. But if we do find signs of an existing intelligent race, humanity may have hope to survive the future.