The theory that a mysterious star might be home to a giant megastructure built by aliens just got a serious reality check.
The star, called KIC 8462852, made headlines in October 2015 when astronomers looked through data from the Kepler Space Telescope and noticed strange fluctuations in the star's light over a 100-day period.
They ruled out a few natural causes and then floated the idea that the fluctuations were caused by a giant megastructure built by aliens. It's no surprise that the story exploded in the media.
Then, another study, published in January, found the star had actually dimmed by 20% over the last century, adding further support to the idea that aliens were building something around the star.
Sorry to disappoint you, but it's probably not aliens. A new paper published in April on the preprint server arXiv has stirred up the debate again. It suggests that the 20% dimming effect observed around the star is simply related to the variety of different telescopes and cameras used to observe it over the last century.
In other words, there's no alien megastructure, Dyson sphere, or alien spaceship around this star.
The team of astronomers behind the new paper looked at observational data spanning from 1885 to 1993 and found a similar effect in other stars like KIC 8462852.
"That indicates the drops were caused by changes in the instrumentation, not by changes in the stars' brightness," study co-author Keivan Stassun said in a statement.
Granted, this new paper still doesn't explain the initial fluctuations observed over a 100-day period. But there are plenty of other natural explanations for it besides aliens. And the study does actually strengthen some of those natural explanations.
The most likely explanation seems to be that the dips in brightness we see around the star are caused by a giant comet that broke apart, and now all the pieces are passing in front of the star.
Additionally, SETI (Search for Extraterrestrial Intelligence) missions haven't found any evidence of radio signals or laser signals coming from the star.
So if there is an alien civilization there, why haven't we heard anything?
"What does this mean for the mystery?" astronomer astronomer Michael Hippke said in a statement. "Are there no aliens after all? Probably not! Still, the dips found by Kepler are real. Something seems to be transiting in front of this star and we still have no idea what it is!"