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(KXAN) — “Paraskevidekatriaphobia,” the scientific term for the fear of “Friday the 13th,” will be in full effect for the second time this year.

(Hopefully, most of us survived unscathed from the unluckiness of the first Friday the 13th of 2020 back in March.)

Frequency

There is at least one Friday the 13th in every calendar year, but there can be as many as three in a single year. The date occurs during any month that starts on a Sunday. When the year starts on a Thursday, Friday the 13th will occur in February, March and November. On a leap year that starts on a Sunday, Friday the 13th will occur in January, April and July. It is thought to be on a 28-year cycle.

The last time we had two Friday the 13ths was in 2019, with occurrences before that in 2013, 2017, 2018. The last time we had three Friday the 13ths was in 2015 and before that, in 2012.

The next time we’ll have two Friday the 13ths will be in 2023, and the next time we’ll have three Friday the 13ths will be in 2026.

Origins

There are many theories on how Friday the 13th earned its reputation of being “unlucky.”

Some historians say the superstition originated from a Norse myth involving 12 gods having a dinner party. An uninvited “13th guest” arrived and shot one of the gods, causing the entire Earth to go dark. That day was deemed a “bad” and “unlucky” day — as was the number 13.

Some roots of the superstition are found in Christianity with the Last Supper, which consisted of Jesus and his twelve disciples the day before he was crucified (Good Friday). Judas, the disciple who betrayed Jesus, is thought to have been the 13th guest to sit down to dinner. Friday was also said to be the day Eve gave Adam the fateful apple from the Tree of Knowledge, as well as the day Cain killed his brother, Abel.

Effects

Behavioral studies have shown millions of people are affected by the fear of Friday the 13th, and it can cause them to alter their normal or daily routine. Some superstitions or avoidances include:

  • Traveling on an airplane
  • Staying on the 13th floor of a hotel
  • Getting a haircut (said to result in the death of a family member)
  • Breaking a mirror (said to result in seven years of bad luck)
  • 13 people at a dinner table (some sit a teddy bear in a chair as a “14th guest”)

According to a study done in September 2019, most Americans said they are “not very superstitious” or “not at all superstitious,” while a small percentage (less than 10%) admit to being “very superstitious.”

COURTESY: Statista

Unfortunate events on Friday the 13th

A number of tragic events have occurred on Friday the 13th, adding to the superstition surrounding the date:

  • The German bombing of Buckingham Palace (September 1940)
  • A cyclone that killed more than 300,000 people in Bangladesh (November 1970)
  • The disappearance of a Chilean Air Force plane in the Andes (October 1972)
  • The death of rapper Tupac Shakur (September 1996)
  • The crash of the Costa Concordia cruise ship off the coast of Italy, which killed 30 people (January 2012)

For more information, visit History.com.