Photo Credit: Black cat rescue via Petco

It is Friday the 13th! Though that fact may be of no significance to you, many consider the combination unlucky. While most years we encounter this dreaded day just once or twice, this year we have had to suffer through it three times.

To make matters worse, in October, the European Space Agency (ESA) announced that a mysterious piece of space debris dubbed WT1190F was expected to come hurtling to earth on this 'unlucky' day. Believed to be a discarded rocket body it was scheduled to enter the atmosphere above the ocean close to Sri Lanka at 11:49 local time (1:19 EST).

Photo Credit: European Space Agency

ESA officials, however, were not worried. They predicted the debris would disintegrate upon entering our atmosphere, and any remains would end up in the Indian Ocean. Though they were right, people already nervous about this ill-fated day were on edge until they saw the fiery footage of WT1190F behaving exactly as ESA had anticipated.

So how did this combination became so feared? There are numerous theories. Some experts believe it starts with the unfounded fear of the number 13 that many of us have. University of Delaware professor Thomas Fernsler thinks that the number's bad reputation stems from the fact that it follows the nicely rounded 12. He believes that most people think 12 is "safe" - After all, there are 12 months, 12 zodiac signs, 12 tribes of Israel, 12 apostles of Jesus . . . So on and so forth. Hence, the odd number that follows is deemed unlucky.

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Folklore historian Donald Dossey thinks that the fear of the number can be traced back to ancient times when the Vikings occupied Scandinavia. According to one famous tale, twelve gods were enjoying a dinner party in their mythological heaven, Valhalla, when an uninvited 13th guest, a god called Loki strolled in. The evil deity instigated Hoder, the blind god of darkness to kill Balder, the god of joy and gladness. Thanks to this myth many people still shy away from hosting dinner parties with 13 guests. In Paris, some businesses get past the odd number by 'renting' a special 14th guest or quatorzieme.

The fear of Friday also comes from ancient mythology. In the Bible, Jesus was crucified on this day. While the date was not the 13th, it was right after the Last Supper, which had 13 guests including Judas Iscariot, the apostle that betrayed Jesus. Some biblical scholars believe that Adam was tempted with the forbidden fruit by Eve on a Friday, though no one knows what date it was. The one sad event that is believed to have occurred on this day and date is the slaying of Adam and Eve's son Abel, by his brother Cain.

Image Credit: Mirror.co.uk

While many of us consider Friday the 13th just the end of a long week, there are over twenty million Americans and scores others around the world, that take the day very seriously. In fact, the fear is so real that it is considered a disorder that goes by the names friggatriskaidekaphobia or paraskevidekatriaphobia. People suffering from this affliction have symptoms that range from mild anxiety to a nagging fear that something bad is about to happen, to even full-blown panic attacks.

Given the widespread paranoia, it is not surprising to hear that many people avoid traveling or making purchases on this day. Some even refuse to leave their homes. It is estimated that American businesses lose between $800 - $900 million USD every time the 13th falls on a Friday. But there is a silver lining for those that are not superstitious - It apparently is the best day to book travel or make other significant purchases because many businesses offer discounts to entice customers. So if you are planning on getting that gaming machine or booking an exotic vacation, today may be a good day to get it done!

Resources: wikipedia.org, telegraph.co.uk, iflscience.com, USAToday,com