The strange behavior of "alien megastructure" star has astronomers worldwide completely perplexed. Tabby's star -- also occasionally called Boyajian's star -- dimmed again last Friday, May 19, spurring astronomers to point as many telescopes as possible in its direction in hopes of finally solving the mystery.

According to a report from New Scientist, the star KIC 8462852 is located 1,300 light-years away in the constellation Cygnus. Its bizarre flicker was first detected back in 2015. The team, led by the star's namesake Tabetha Boyajian, saw it dim suddenly and repeatedly by up to 22 percent before it went back to normal.

A review of old photographic plates revealed that this is not the first time this phenomenon occurred. Between 1890 and 1989, the "alien megastructure" star also decreased in brightness by 14 percent. Over the four years, Kepler space observatory detected that Tabby's star faded an additional 3 percent.

No one knows for sure what is causing this strange flickering of Tabby's star. There are several theories floating around, though. The most famous theory so far is that the dimming is caused by an "alien megastructure" orbiting the star and collecting stellar energy.

Another possibility is an interstellar cloud located between Kepler and Tabby's star, which seems to be one of the most likely explanations conceptualized so far, according to a report from Space.com. However, not everyone is convinced this is the reason behind Tabby star's weird behavior.

"That would have to be some crazy interstellar cloud," Pennsylvania State University astronomer Jason Wright, who led a study on the puzzling star in 2016, pointed out. He added that scientists may dig deeper to find the real cause of the phenomenon. "I think it's very likely that we haven't heard the right answer yet - that I haven't heard the right answer yet, anyway."