Friday the 13th is considered a day of bad luck in English-, French- and Portuguese-speaking countries around the world, as well as in Austria, Germany, Estonia, Finland, The Netherlands, Belgium, Republic of Ireland, Poland, Bulgaria, Denmark, Iceland, Sweden, Norway, Czech Republic, Slovakia, Slovenia, Hungary, and the Philippines.

Similar superstitions exist in some other traditions. In Greece, Romania and Spanish-speaking countries, for example, it is Tuesday the 13th that is considered unlucky. In Italy, it is Friday the 17th.

The fear of Friday the 13th is called paraskavedekatriaphobia,^[1], a word derived from the concatenation of the Greek words Paraskeví (Παρασκευή) (meaning Friday), and dekatreís (δεκατρείς) (meaning thirteen), attached to phobía (φοβία) (meaning fear). The term is a specialized form of triskaidekaphobia, a simple phobia (fear) of the number thirteen appearing in any case.

History

number thirteen  have been considered unlucky:

• In numerology, the number twelve is considered the number of completeness, as reflected in the twelve months of the year, twelve recognized signs of the zodiac, the twelve tribes of Israel, the twelve Apostles of Jesus, etc., whereas the number thirteen was considered irregular, transgressing this completeness.^[2] There is also a superstition, thought by some to derive from the Last Supper, that having thirteen people seated at a table will result in the death of one of the diners.
• Friday, as the day on which Jesus Christ was crucified, has been viewed both positively and negatively among Christians. The actual day of Crucifixion was the 14th day of Nisan in the Hebrew Lunar calendar which does not correspond to "Friday" in the solar calendar of Rome. The 15th day of Nissan (beginning at Sundown) is celebration of Passover.

Despite the reputation of the two separated elements, there is no evidence for a link between the two before the 19th century. The earliest known reference in English occurs in a 1869 biography of Gioachino Rossini:

[Rossini] was surrounded to the last by admiring and affectionate friends; and if it be true that, like so many other Italians, he regarded Friday as an unlucky day, and thirteen as an unlucky number, it is remarkable that on Friday, the 13th of November, he died.^[3]

However, only in the 20th century did the superstition receive greater audience, as

Friday the 13th doesn't even merit a mention in E. Cobham Brewer's voluminous 1898 edition of the Dictionary of Phrase and Fable, though one does find entries for "Friday, an Unlucky Day" and "Thirteen Unlucky." When the date of ill fate finally does make an appearance in later editions of the text, it is without extravagant claims as to the superstition's historicity or longevity.^[4]

Though the superstition developed relatively recently, much older origins are often claimed for it, most notably in the novel The Da Vinci Code (and later the film), which traced the belief to the arrest of the Knights Templar on Friday October 13, 1307.^[4]

[edit] Effects in people and cultures

According to the Stress Management Center and Phobia Institute in Asheville, North Carolina, an estimated 17 to 21 million people in the United States are affected by a fear of this day. Some people are so paralyzed by fear that they avoid their normal routines in doing business, taking flights or even getting out of bed. "It's been estimated that [US]$800 or $900 million is lost in business on this day".^[2] Despite this, representatives for both Delta and Continental Airlines say that their airlines don't suffer from any noticeable drop in travel on those Fridays.^[5]

A British Medical Journal study has shown that there is a significant increase in traffic-related accidents on Fridays the 13th.^[6]

This sequence, here given for 2001–2028, repeats every 28 years from 1901 to 2099. The months with a Friday the 13th are determined by the Dominical letter (G, F, GF, etc.) of the year. Any month that begins on a Sunday will contain a Friday the 13th.

Every year has at least one and at most three Fridays the 13th, with 688 occurrences during each 400-year Gregorian cycle (146,097 days).^{[citation needed]}

The longest period that can occur without a Friday the 13th is fourteen months, either from July to September the following year (e.g. in 2001/2002 and 2012/13), or from August to October in a leap year (e.g. in 2027/28).

Each Gregorian 400-year cycle contains 146,097 days (365 * 400 = 146,000 normal days plus 97 leap days), 146,097 / 7 = 20,871 weeks, and 400 * 12 = 4,800 months. Thus, each cycle contains the same pattern of days of the week (and thus the same pattern of Fridays the 13th), but no day of the month up to the 28th can occur the same number of times on each day of the week (because 4,800 is not divisible by 7). The 13th day of the month is slightly more likely to be a Friday than any other day of the week.^[7] On average, there is a Friday the 13th once every 212.35 (212 and 241/688) days.

The distribution of the 13th day over the 4,800 months is as follows:

[edit] Planned events on Fridays the 13th

Some events are intentionally scheduled for Friday the 13th for dramatic effect. They include:

• The 2008 Tamil block-buster film Dasavatharam is planned to release on Friday, June 13, 2008 in India, Malaysia, Singapore, Australia, USA and UK.
• Black Sabbath's eponymous debut album was released in the UK on Friday, February 13, 1970.
• The 13th book in A Series of Unfortunate Events was released on Friday, October 13, 2006 by Lemony Snicket, also known as novelist Daniel Handler.
• Friday the Thirteenth, a gathering for motorcycle enthusiasts held in the Canadian beach town of Port Dover, Ontario every Friday the 13th.
• The 2008 film The Happening is planned to release on Friday, June 13, 2008.
• The first TV special on iCarly, "iCarly Saves TV" is planned to be aired on June 13, 2008.
• The Incredible Hulk is planned to release on June 13, 2008.
• The Canadian release of the Microsoft's Zune music player is on June 13, 2008.
• The remake of the original Friday the 13th is planned to release on Friday, February 13, 2009.

[edit] Natural events on Fridays the 13th

Due to the large number of events that happen in the world, a similar list could be compiled for any combination of day of the month and day of the week.

• The Black Friday bushfires in Victoria, Australia occurred on Friday, January 13, 1939.
• The Uruguayan Rugby team infamously crashed in the Andes mountain range on Friday, 13 October 1972
• Hurricane Charley made landfall near Port Charlotte, Florida on Friday, August 13, 2004.
• The "Friday the 13th Storm" struck Buffalo, New York on October 13, 2006.
• UNIX time will reach 1,234,567,890 decimal seconds on February 13, 2009 at 23:31:30 GMT.
• The asteroid 99942 Apophis will make its close encounter on Friday, April 13, 2029.

[edit] Notable births and deaths