Not long ago, scientists stumbled upon one of the weirdest things they have ever encountered in space, and today, it’s behaving very strangely yet again. In 2015, astronomers found a planet near KIC 8462852, or Tabby’s Star, and it’s been going through dramatic and random periods of getting dimmer and then brightening again.

It’s led to all sorts of speculation on what it can be, with one of the more outlandish theories positing that there is some sort of alien megastructure that is causing the dimming. It’s not uncommon for stars to get dim when planets or clouds of dust pass in front of them, but usually this happens on a regular schedule and only results in slight dimming, whereas this is much more random and leads to more significant dimming.

The star, located about 1,400 light years away from us, is once again showing signs of a major dimming event, causing astronomers to study the star closely to crack the mystery.

“A star known by the unassuming name of KIC 8462852 in the constellation Cygnus has been raising eyebrows both in and outside of the scientific community for the past year,” reads a 2016 statement from the Carnegie Institution for Science. “In 2015 a team of astronomers announced that the star underwent a series of very brief, non-periodic dimming events while it was being monitored by NASA’s Kepler space telescope, and no one could quite figure out what caused them. A new study from Carnegie’s Josh Simon and Caltech’s Ben Montet has deepened the mystery.

“Simon and Montet’s findings caused a stir in August, when they were posted on a preprint server while their paper was being reviewed. Now their work is now accepted for publication by The Astrophysical Journal.”