When astronomers observe cosmic events that defy immediate explanation, a knee-jerk public response often follows chalking it up to alien beings, on alien worlds, doing alien stuff. This dynamic was on full display back in 2015, when an obscure star named KIC 8462852 was thrust into the spotlight after the discovery that it is occasionally eclipsed by a large, unknown structure.
The initial study on the star’s dimming events was led by Louisiana State University astronomer Tabetha Boyajian, who also manages the citizen science project Planet Hunters. Her team suggested that the light fluctuations might be caused by dust clouds or fragmentary planetary bodies (as a result of Boyajian’s efforts, KIC 8462852 is now informally known as “Tabby’s Star").
But when Penn State University astronomer Jason Wright spitballed that the star-blocking agent might be a swarm of megastructures built by an advanced alien species, the story naturally became the subject of intense interest worldwide. Could this mild-mannered star, which is around 50 percent bigger than our Sun and is located some 1,200 light years from Earth, be home to an extraterrestrial civilization?
The signs always pointed to no, but now, two years later, it is about as official as astronomy can get. On Wednesday, a major Boyajian-led study published in the Astrophysical Journal Letters leaves the “alien megastructures” theory in the dust—literally.
With the help of over 100 co-authors, including Wright, Boyajian presents observational evidence from real-time monitoring of the star, which bolsters the idea that the dimming events are caused by dust clouds.
“Our observations mark the first real-time detection of a dip in brightness for KIC 8462852,” Boyajian’s team wrote in the paper, referring to the so-called “Elsie” series of dips that began in May 2017.
The Elsie series—which is subdivided into four main phases called Elsie, Celeste, Skara Brae, and Angkor—was studied across the light spectrum at the Las Cumbres Observatory in California. These observations showed that some wavelengths of light were blocked at different levels than others, which suggests that the structures occulting KIC 8462852 are transparent enough to let select bands of light pass through. Inhabited worlds or alien robot swarms would presumably be opaque, blocking all light, so they are unlikely to be the occulting structures.
With that said, there are still plenty of interesting theories that could explain the origins and behavior of these speculative dust clouds. One particularly dramatic scenario involves a planetary collision around 1,000 years ago that sent the shattered shards of former worlds into a highly elliptical orbit around the star. If this is true, the researchers expect to see another dimming event in June 2019, which would establish some periodicity to the otherwise unpredictable light dips.
These new revelations may not live up to the alien hype for some, but it’s worth noting that immense public interest in the star—buoyed on by talk of E.T.—has helped Boyajian and her colleagues channel a variety of resources into better understanding this tantalizing system. Whatever process is dimming the luminosity of KIC 8462852 is a rare outlier event, and it could yield insights about any other stars with similar signatures, even if they aren’t so extreme.
There’s also value in the fact that the latest study sources research not only from major academic institutions, but from citizen scientists who first helped spot the dimming events, and who crowdfunded research projects on Kickstarter to try to explain them. This grassroots activism may portend a more collaborative approach to astronomy in the future, while providing a model for other scientific teams who are looking to engage as many people as possible in their work.
“KIC 8462852 has captured the imagination of both scientists and the public,” Boyajian and her co-authors noted. “To that end, our team strives to make the steps taken to learn more about the star as transparent as possible.”