Friday the 13th: 5 things to know

Third time's the charm? It's Friday the 13th again in 2015!

And it doesn't HAVE to be unlucky. Here are five things to know about the date:

1. Why are we so scared of it? 

Fear is likely rooted in Christianity. Jesus was crucified on a Friday and ever since the day has been associated with "general ill omen," Michael Bailey, a history professor at Iowa State University who specializes in the origins of superstitions, told USA TODAY Network.

Weddings in the Middle Ages, for instance, were not held on Fridays and it was not a day someone would start a journey, Bailey said.

Thirteen guests are believed to have attended the Last Supper, the night before Jesus was killed, according to Stuart Vyse, a psychology professor at Connecticut College. And Judas Iscariot, the disciple who betrayed Jesus, is considered to have been the 13th guest, Vyse said.

2. What are the origins of Friday the 13th? 

The superstition's origins are mysterious. It's unclear when Friday and number 13 became linked in the way we think of them today, according to Vyse and Bailey. There are no mentions of Friday the 13th before the 19th century.

Vyse said you can largely blame your family for passing on the superstition of Friday the 13th.

"It would be hard to find someone in the U.S. that doesn't know about Friday the 13th,"  Vyse said. "We are all taught about it at a young age."

Vyse said there is almost a "two mindedness" people experience regarding Friday the 13th.

“Research shows that for some people it doesn’t matter if they know having a 6-6-6 license plate or staying on the 13th floor of a hotel means nothing, they want to exercise the superstition or be influenced by it even if it’s irrational,” Vyse said.

3. Of course, fear of the day has an official name.

It's called paraskevidekatriaphobia. Not sure how to pronounce it? NPR offers this handy audio guide.

4. No. You're not more likely to make a trip to the hospital.

A 2011 German study published in the World Journal of Surgery explored whether there is a link between Friday the 13th and an increase of blood loss and the frequency of emergency room visits on those days.

Researchers reviewed 3,281 days at a hospital facility that included 15 Friday the 13ths. They found no correlation.

"Our data indicate that such beliefs are myths far beyond reality," the study concludes.

5.Trilogy! There are three Friday the 13ths in 2015. 

Nov. 13, 2015 is the third of three Friday the 13ths this year. Other dates this year include February 13 and March 13. In 2014, Friday the 13th came along once on June 13. After Friday, we'll have to wait until May 13, 2016 for the next "unlucky" date.

Why a trilogy of Friday the 13ths in 2015?

According to EarthSky.org, since the year 2015 started on a Thursday, February, March and November will start on Sunday in a common year. "And any month starting on a Sunday always has a Friday the 13th," according to the website.

Bonus fact: 13 is Taylor Swift's lucky number.

"I was born on the 13th. I turned 13 on Friday the 13th. My first album went gold in 13 weeks. My first #1 song had a 13-second intro," the singer told MTV in a 2009 interview.

The performer was even sued in 2014 by the clothing brand Lucky 13 for selling T-shirts on her online store with the phrase "Lucky 13" on them.

Contributing: Jolie Lee and Lori Grisham for USA TODAY Network