The number thirteen is far more than just a prime number. Even today, many people are subconsciously afraid of 13, while for others it is a lucky number. No other number causes as much of a stir in society around the world as 13. In many buildings, the 13th floor has even been left out because of the superstition surrounding the number.

 

Why thirteen is considered an unlucky number is not entirely clear. There is a theory that the number 13 brings bad luck since the last 13 Knights Templar were burnt alive to end the Crusades and this happened on a Friday the 13th. Another theory centres on the lunar calendar. In some years there are 13 full moons instead of 12, which confuses church holidays. As a result, years with 13 full moons are said to be unlucky years. Regardless of where 13 got its reputation for being unlucky, there are so many people who are afraid of the number 13 that this phobia even has a name: Triskaidekaphobia.

 

The number 13 does not bring bad luck in every society; for many peoples it is even a lucky number. In Punjabi, the number 13 is pronounced "tera", which means "I am yours". Colgate University considers the number 13 to be a lucky number because the university was founded by 13 men with 13 dollars, 13 prayers and 13 reports. The university is located at number 13 Oak Drive, and for the members of the university, anything related to 13 is a good omen. In Italy, too, 13 is considered a lucky number.

 

In Sikhism, the foundation of the Khalsa is celebrated on 13 April. In Hinduism, a feast (Tehranvi) is organised 13 days after a death to give eternal peace to the deceased. In the Catholic religion, the famous visions of Fatima appeared to the Virgin Mary every 13th for six months in 1917. Judaism celebrates the 13th birthday of boys with the Bar Mitzvah. In addition, the Torah of God mentions 13 attributes of grace.

 

The original US flag had exactly 13 stars, the current flag has 13 stripes as a reminder of the original 13 colonies.

NASA's only failed moon mission was Apollo 13; it was shot down on 11 April 1970, and two days later, on 13 April, the mission had to be aborted due to a broken oxygen tank.