Star KIC 8462852 caused quite a kerfuffle when scientists noted its unusual flicker. To make a long story short, the Kepler Space Telescope checks out distant exoplanets by monitoring the dimming of their host stars. A star dims a certain way (at least from Earth's perspective) when a planet is passing in front of it. KIC 8462852 had a flicker to be sure, but not any kind that scientists had seen before, ergo maybe aliens???
One possible explanation that was floated was pretty fantastic, and even the scientists who brought it up said it was highly improbable: The flickering could be caused by some kind of alien-made, artificial structure.
In the past few weeks, scientists watching KIC 8462852 have put more and more ticks in the "totally not aliens" column, which I assume is a thing that SETI scientists actually have on their desks. The SETI institute reported that radio telescopes tuned in to KIC 8462852 had failed to pick up any relevant radio signals, and another research group suggested that a trail of comets might be to blame for the irregular flickering.
In a paper submitted to The Astrophysical Journal Letters, researchers report a failure to detect laser pulses from the strange star. So if there are aliens, they've been incredibly quiet on all fronts -- probably too quiet, considering they're meant to have built a Dyson Sphere around their star.
“The hypothesis of an alien megastructure around KIC 8462852 is rapidly crumbling apart,” study author Douglas Vakoch, President of SETI International, said in a statement. “We found no evidence of an advanced civilization beaming intentional laser signals toward Earth."
The researchers used the Boquete Optical SETI Observatory in Panama to search for laser pulses as short as a billionth of a second on six consecutive nights. The star is so far away that any lasers we received from a civilization there would have to have been sent during the dawn of the Roman Empire -- but the researchers say they could have detected even laser pulses that had made such a long journey. Unfortunately, they just weren't there.
It's great that scientists are working so hard to rule aliens out, even though the chances seemed slim from the start. One day, if we're really lucky (or unlucky), we could detect a signal that really is from another intelligent civilization. If and when that day comes, we'll have honed our alien-detecting skills and be more than ready to confirm the world-changing news.