The “rare” spectacle of Manhattanhenge happens but twice a year. Friday the 13th and a full moon falling on the same day won’t happen for another 30. Tonight, look up into the night sky while simultaneously watching your back, because this is the first full moon that’s occurred on Friday the 13th since October, 2009 and will be the last until August, 2049. Okay, so that’ll be before the next Halley’s Comet, but in the scope of things, rare. It’s also a Harvest Moon–the full moon closest to the fall equinox.

With Halloween already being foisted on us by retailers and the advent of a full moon falling on a cursed day, we figured we’d do a little research on what makes all those things spooky. The unluckiness of Friday the 13th dates back just 150 years, but the number 13 being unlucky and, separately, Fridays being unlucky, may date back to the Biblical story, where there were 13 people at the last supper. Interestingly, in Spanish-speaking countries, Tuesday the 13th is considered unlucky, and in Italy it’s Friday the 17th.

While all that is based in superstition, how about the full moon? Does it really cause luna(cy)? The moon’s gravitational force effects bodies of water, so some believers submit that, since the human body is 80% water, it has a disruptive effect on us. Scientists have debunked this theory, however the increased occurrence of erratic and even criminal behavior on the full moon is undeniable. Scientists and criminologists offer up a logical explanation: there’s more light. Studies have shown that there is not an increase in indoor criminal activity on a full moon, just outdoor criminal activity.

So is Friday the 13th even spookier because of a full moon? Probably not. But it’s a fun excuse to go looking for a black cat so you can experience the trifecta!