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SYFY WIRE Bad Astronomy

So What Exactly Is an “Alien Megastructure”?

By Phil Plait

Last week, I wrote another article about KIC 8462852, aka Tabby’s Star, which is behaving very oddly indeed. It shows sharp dips in brightness that last for hours, as well as much longer ones that last for days (or longer) that indicate something is blocking a substantial fraction of the star’s light.

The most likely explanation is a cloud of dust with comets or asteroids embedded in it, which can cause the star to dim. However, it’s been maddeningly difficult to explain all the star’s behavior with this natural model. So, ever since its discovery and perhaps a bit sheepishly at first, astronomers have toyed with the idea that maybe what we’re seeing is evidence of an advanced alien civilization.

To be clear, no one is saying that’s what’s going on. But it’s a cool idea, and worth investigating at least a little. No radio signals have been seen from the star, though, and no other indication of aliens has been found.

Still, it’s fun to think about. The premise is that aliens are building huge panels of some kind around the star in order to capture more of its light to power their civilization (imagine it like the ultimate work of a Little Green Elon Musk). The idea of alien megastructures has been around a while, and has some merit as a thought piece.

Astronomer David Kipping, who studies Tabby’s Star, made a short video explaining all this simply and engagingly. He does a great job summing up what we know:

Kipping studies exoplanets and moons, and he and I agree strongly on this topic. It’s fun, it’s interesting, no astronomer really thinks this is what’s happening for sure, but it’s a compelling idea and well worth looking into. You know, just in case.

For more details and insight into what’s going on with Tabby’s Star, astronomer Jason Wright also made a video diving into the topic more deeply:

Back when all this started I had a long and very engaging conversation with Jason about it, and his take on it is grounded in reality and firmly based on evidence. His conclusion, like all the rest of ours, is that this is a highly intriguing star, its behavior is almost certainly natural, but it’s stimulating and perhaps even rewarding to look into more speculative explanations. They’re unlikely to turn out correct, but they stretch our imaginations and exercise our brains in a way that can be helpful in solving mysteries.

So, as usual, I’m still not saying aliens. But no matter what this turns out to be, it’s wonderful and stimulating, and just good old fashioned fun for a scientist to think about.

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