More Megastructure Mystery

On Monday, I arrived at KIC 8462852, better known as Tabby’s Star, and discovered that yes, the aliens really are building a megastructure. My next question is: how long has this been going on?

These aliens are not turning out to be all that friendly. Fortunately, there’s been some investigative work done back on Earth.

Astrophotography has been around for well over a century now. Even though no one paid much attention to Tabby’s Star until recently, that region of the sky has been photographed before. So following the publication of Tabetha Boyajian’s WTF paper, astronomer Bradley Schaefer started checking those old photographic plates.

And according to Schaefer’s findings, Tabby’s Star has been decreasing in brightness since at least 1890. It would seem the megastructure has been growing in size, obscuring more and more of the star, for quite some time now.

But can we trust the accuracy of those old photographic plates? According to astronomer Michael Hippke and colleagues, no. No we can’t. The degree of uncertainty is too high, Hippke claims, to make a conclusive determination about Tabby’s Star’s brightness over time.

There’s been a pretty intense argument between Schaefer and Hippke ever since. If nothing else, it’s an excellent example of how scientists debate each other. Click here to read Schaefer’s side of it, and click here for Hippke’s.

So if Schaefer is right, construction of the megastructure may have been underway circa 614 C.E. (that’s 1890 C.E. minus the 1276 years it takes for light from Tabby’s Star to reach Earth). And if Hippke’s right… well, who knows when the aliens got started? They’re certainly not telling.