MIAMI (CBSMiami) — Today is Friday the 13th, a date many people associate with bad luck, but is Friday the 13th as unlucky as many people believe?

Not likely, but don’t tell that to someone who hides under the covers every time Friday the 13th rolls around on the calendar because that person probably suffers from paraskevidekatriaphobia, the scientific word for someone who has a fear of Friday the 13th.

It’s derived from the Greek words for Friday and thirteen with phobia, or fear, tacked on.

There are many theories about why Fridays which fall on the 13th day of the month are unlucky.

Some believe that the Friday the 13th superstition has an origin in Norse mythology. In one story, the evil god Loki is said to have crashed a party with 12 guests and tricked the blind god Hod into killing his brother Balder, the god of light, joy and reconciliation.

Also, according to Norse mythology, it was the Vikings who decided a hangman’s noose should have 13 loops and in British tradition, Friday was the conventional day for public hangings, and there were supposedly 13 steps leading up to the noose.

Others believe Friday the 13th has origins in Christianity. According to the Bible, Jesus was crucified on a Friday, and there were 13 men at the Last Supper — Jesus and his 12 disciples. In addition, Judas the disciple who betrayed Jesus, was the 13th to sit at the table and, for that reason, 13 is considered to carry a curse of sorts.

At some places it is also believed that it was Friday the 13th when Eve tempted Adam with the forbidden fruit.

Another significant piece of the legend is a particularly bad Friday the 13th that occurred in the Middle Ages. On this day in 1306, King Philip of France arrested the revered Knights Templar and began torturing them, marking the occasion as a day of evil. Both Friday and the number 13 were once closely associated with capital punishment.

In Numerology, every number has a particular meaning. The number 13 symbolizes “Death”. It’s a picture of a skeleton with a scythe, reaping down men.

Tradition also has it that God confounded languages at the tower of Babel on a Friday the 13th, and Solomon’s Temple was destroyed on a Friday the 13th.

Friday is named for Frigga, the goddess of love and fertility who was exiled in shame to a mountain and labeled a witch. Some believe that every Friday, Frigga held a meeting with 11 other witches and the devil – a group of 13 – and plotted ill deeds for the upcoming week.

By some estimates, businesses lose millions of dollars on Friday the 13th because people are hesitant to make deals, travel or shop as they would at other times.

In France, a dinner for 13 is thought to be unlucky, and superstitious hosts may hire a “quatorzieme,” a professional 14th guest.

Many cities do not have a 13th Street or a 13th Avenue and there is no gate 13 at many airports, the numbers go from twelve to fourteen.

The state lotteries of France, Italy and elsewhere never sell tickets with the number 13.

The fear of 13 has also prompted most high-rise buildings not to have a 13th floor. Hotels do not have room number 13.

But no matter what the origin, the fact is that many people are superstitious about the number 13 and are highly superstitious when it falls on Friday.

Any month’s 13th day will fall on a Friday if the month starts on a Sunday.