We've told you before about how some of the most ridiculous things you've seen in movies are actually based on reality , but it goes much deeper than that: Not only the plots, but the often absurd or simplistic tools that filmmakers use to get their points across are more based in reality than you might think.

5 Full Moons Mean Something Horrible Is Coming

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A full moon is one of the classic portents of doom. If a director takes the time to insert a shot of it, you can rest assured that things are about to get full-on freaky. It happens a lot in werewolf movies (obviously), but it can show up in damn near anything -- like The Evil Dead, which shows you this ...

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Moments later, zombie Elliot and E.T. plummet out of the sky.

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... right before the Dark Power shows up and Bruce Campbell starts chainsawing everyone for no reason.

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Well, OK, he may have had a legitimate reason.

But Sam Raimi certainly didn't invent the technique, and it's not limited to horror films. Here's a shot from The Lord of the Rings: The Two Towers, from right before Faramir tricks Frodo into betraying Gollum, which in turn leads to Gollum betraying the hobbitses right back (only better, because he does it with the assistance of a big-ass spider):

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That's the moon. The big-ass spider comes later.

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Obviously, a full moon isn't some supernatural portent of doom in the real world. Movies just use it to symbolize the fact that bad stuff is about to go down because ... well, just because.

But in Reality ...

Wait a minute, why are people so freaked out by the moon in the first place? We're talking about the most powerful natural source of light at night here -- you'd think the cultural standard would be to give the moon a nod and say, "Thanks, moon. You're all right in our book." And it's not just movies: Folklore has connected the full moon to almost everything confusing and scary throughout human history, from werewolves to gods to women's menstrual cycles. Even the word "lunacy" comes from the Latin word for "moon." Why is that?