For decades, humanity used giant radio telescopes to scan the skies for signs of alien intelligence. The thinking goes, a smart species in the cosmos will probably be sending out radio signals the way humans do. Find these signals, and we’ve found aliens. So far, however, it’s been a bust. The advent of new optical technology, however, raises a new argument: to find aliens, we should find evidence of super advanced megastructures floating in space.

Spring-boarding off that idea, a pair of astronomers have suggested that we should start looking for defense mechanisms — like shields or other barriers to protect against cosmic threats such as supernovae, gamma rays, or even solar flares — as signs of alien life. Milan Cirkovic and Branislav Vukotic published a recent paper in the journal Acta Astronautica that suggests advanced alien civilizations could engineer protective shields by using celestial objects in their vicinity in order to protect themselves from the catastrophic effects of supernovae blasts or gamma ray bursts. They argue such shields would not be that complicated to build and could even be constructed by a civilization that is just a few decades more advanced that we are.

NASA’s Kepler Space Telescope is arguably the best planet-hunter in the galaxy — which makes it one of the best tools we have for scanning space for such alien defense systems. Kepler searches for transits, or tiny dips in a star’s light as an object (like a planet) passes in front of it. These same dips (or transits) could point to protective structures built by advanced civilizations.

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A view of the Very Large Array, one of several radio telescope observatories around the world.
A view of the Very Large Array, one of several radio telescope observatories around the world. 

This is perhaps not as farfetched as it might sound. Last October, Kepler scientists set the internet a blaze as they announced the detection of an unusual light pattern coming from KIC 8462852, a star roughly 2,000 light-years away. The strange pattern appeared to be circling the planet, and scientists cannot agree yet on what is causing it. The orbiting cluster could be a comet that is disintegrating or even a cluster of comets. Or, perhaps, it could be something else entirely — like a Dyson sphere or other alien megastructure.

It’s a remote possibility — but one that many scientists are seriously considering. Cirkovic and Branislav are basically just taking that a step further and suggesting we actively look for such structures as part of SETI research.

Artist conception of the strange structure observed around Tabby's star.
Artist conception of the strange structure observed around Tabby's star. 
Photos via NRAO, Wikimedia , Energy Physics