Now We See You, Now We Don't?

So things around the star KIC8462852 have gotten more interesting recently.

Late last year, items were published noting an irregular dimming and brightening of the star, some 1,500 light-years from Earth. When those kinds of changes happen on a schedule, astronomers think a star may have planets. But planets have regular orbits, meaning that the dimming and brightening would happen on a schedule. The dimming and the brightening of KIC8462852, though, doesn't, which makes planets an unlikely cause.

One speculation was that an extraterrestrial civilization was building a gigantic construct around the star that sometimes eclipsed part of its light. Rather than the Dyson Sphere, which would surround a star completely and cut off all of its light, the admittedly outlandish theory was that it might have been a Dyson "swarm" or "cloud." The aliens weren't building one impossibly immense structure, but instead several improbably immense structures that obscure part of its light on an irregular basis.

The more likely explanation, most astronomers figured, was cloud of huge comets, whose irregular orbits would provide the same effect. So the solution was found and everyone went away happy.

Except Bradley Schaefer of Louisiana State University, who continued research on KIC8462852 and discovered that it had been doing this irregular brightening-dimming thing since it had been first observed by Harvard University astronomers in 1890. For irregular comets to keep that up, Schaefer estimated that there would have to be almost 650,000 comets of at least 125 miles in diameter orbiting KIC8462852, and that option's off the table.

For the record, Schaefer doesn't necessarily believe aliens are building gigantic sun shades. But he notes that so far, the data don't support offered natural hypotheses, which at the very least means that he and other astronomers will need to keep looking.