For the first time in 11 years, Friday the 13th is falling in two consecutive months. This double threat can only occur in certain non-leap years and only in a February-March combination. Look for it—or avoid it—again in 2015. The double whammy isn't the only Friday the 13th claim to infamy for 2009, a particularly tough year for superstitious minds.
The ominous date falls on three Fridays this year: February 13; this Friday, March 13; and again on November 13.
But three Friday the 13ths is the yearly maximum, as long as societies continue to mark time with the Gregorian calendar, which Pope Gregory XIII ordered the Catholic Church to adopt in 1582.
"You can't have any [years] with none and you can't have any with four because of our funny calendar," said Underwood Dudley, a professor emeritus of mathematics at DePauw University in Greencastle, Indiana, and author ofNumerology: Or, What Pythagoras Wrought.
The calendar works just as its predecessor the Julian calendar did, with a leap year every four years. But the Gregorian calendar skips leap year on century years except those divisible by 400. For example, there was no leap year in 1900 but one was observed in 2000. This trick keeps the calendar in tune with the seasons.
The result is an ordering of days and dates that repeats itself every 400 years, Dudley noted. As time marches through the order, some years such as 2009 appear with three Friday the 13ths. Other years have two or one.
Curious Calendar
"It's just that curious way our calendar is constructed, with 28 days in February and all those 30s and 31s," Dudley said.
When the 400-year order is laid out, another revelation occurs: The 13th falls on Friday more often than any other day of the week. "It's just a funny coincidence," Dudley said.
"At the end of every cycle you get a year with three Friday the 13ths the year before the last year in the cycle … and you also get one on the tenth year of all the cycles," he said. Two-thousand nine is the tenth year of the cycle that started in 2000.
Is it really unlucky number !!!
In history too this number was always considered as unlucky number … in last supper with Jesus, Judas was the 13th guest who betrayed him … in ancient Rome, witches reportedly gathered in groups of 12. The 13th was believed to be the devil !!! In Norse myth tale when about 12 gods having a dinner party at Valhalla, their heaven. In walked the uninvited 13th guest, the mischievous Loki. Once there, Loki arranged for Hoder, the blind god of darkness, to shoot Balder the Beautiful, the god of joy and gladness, with a mistletoe-tipped arrow, another example !!! numerologists consider 12 a "complete" number. There are 12 months in a year, 12 signs of the zodiac, 12 gods of Olympus, 12 labors of Hercules, 12 tribes of Israel, and 12 apostles of Jesus. In exceeding 12 by 1, 13's association with bad luck "has to do with just being a little beyond completeness. The number becomes restless or squirmy”. How can we forget apollo 13, right ??? Some biblical scholars believe Eve tempted Adam with the forbidden fruit on Friday. Perhaps most significant is a belief that Abel was slain by his brother Cain on Friday the 13th. We all know that Jesus was crucified on Friday … right ??
Modern Trend ???
actually its not like that people used to do this from all the time …
"It's been estimated that [U.S] $800 or $900 million is lost in business on this day because people will not fly or do business they would normally do," said Dossey, who is also the founder of the Stress Management Center and Phobia Institute in Asheville, North Carolina.
Among other services, Dossey's organization counsels clients on how to overcome fear of Friday the 13th, a phobia that he estimates afflicts 17 to 21 million people in the United States !!!
This fear of 13 can even be seen in how societies are built. More than 80 percent of high-rise buildings lack a 13th floor. Many airports skip the 13th gate. Hospitals and hotels regularly have no room number 13.On streets in Florence, Italy, the house between number 12 and 14 is addressed as 12 1/2. In France, socialites known as the quatorziens (fourteeners) once made themselves available as 14th guests to keep a dinner party from an unlucky fate !!!
Well personally , i don’t believe in this myth … i believe there is only one thing unlucky for us and it is we are to each other !!! 
Njoy …
