A couple of years ago it came to the world’a attention that a certain star was behaving strangely. The Kepler Space Telescope had actually caught it in the act for several years, but it wasn’t discovered in that ginormous database until 2015.
The big dips in luminosity could not come from natural variability; the star is a main sequence type-F, almost the same as our own sun. We have observed millions of these kinds of stars, astrophysicists understand them, and they simply do not vary much in brightness. That brought up other explanations: clouds of comets, disintegrating planets, giant ring arcs, a small black hole eating the star from within, etc., and of course speculation of massive engineering projects like Dyson Spheres signaling an advanced alien civilization.
It is classified as KIC 8462852, but it’s since been dubbed Tabby’s Star after Tabetha S. Boyajian, an astronomer who did some initial work on the anomaly. The problem is that up until now, all we had were some incidental observations over the last few decades when the star was caught in the background of other photos and the Kepler data. But the strange star has begun to dip again and now that we are looking with some of our best instruments, we may finally learn more.
At 4 a.m. on May 19th, Boyajian called Wright: Fairborn Observatory in Arizona had issued an alert that Tabby’s star had dimmed by 2% — a big dip in the star’s brightness. The team immediately sent out the call for more observations. … “This is the first time we’ve seen a clear dip since the Kepler mission, and also the first we’ve caught in real time,” says Wright. “The changes are as steep as we ever saw it change brightness with Kepler. It’s going to be a busy couple of weeks.”
For the record, one of the best explanations so far involves a swarm of large comets in a highly eccentric orbit with lots of smaller bodies and gas and dust in between them. How accurate that turns out to be—and how a presumably mature system ended up in this chaotic state—are some of the questions we may finally see answered in the next few months.