Pic is of a tree that fell in a snowstorm on a street in Buffalo, New York, on Friday 13th October 2006. It is by DragonFire1024 at Wikimedia.
Every year our calendar has at least one Friday 13th. This year we've had three, in February, March, as well as today.
If you are among the many folk particularly wary of Friday 13th, you are suffering from paraskevidekatriaphobia, or the slightly easier to pronounce friggatriskaidekaphobia – two names for the same phenomenon. Triskaidekapohobia on its own just means fear of the number 13.
There are plenty of theories about the origins of these phobias.
§ There are 13 witches in a coven.
§ Christian ideas relate it to the crucifixion happening on a Friday, also the last supper attended by Christ and the 12 apostles, the 13th being Judas Iscariot, the traitor.
§ Some believe it had an earlier origin when the Norse god Odin was entertaining 11 of his friends at Valhalla and his crafty brother, Loki, turned up uninvited, changing the party total to 13. It was at this party that Loki managed the tragic demise of Baldur, son of Odin and Frigga.
§ It was on Friday 13th October, 1307 that the Knights Templar across France were arrested en masse, to suffer torture and death at the whim of the Pope who had been jealous of their power.
Some famously nasty happenings have been linked to Friday and/or the number 13, but sometimes these links do seem rather contrived.
§ The crew members of the Apollo 13 mission failed to land on the moon, and were lucky to get home following an oxygen tank explosion on board. They were launched from Pad 39 (3 x 13) at 13:13 hours (not local time, but Houston mission control time) on 11th April, 1970 (11 + 4 + 70 = 85, and 8 + 5 = 13).
§ Composer Arnold Schoenberg was afflicted with triskaidekaphobia. Born on the 13th day of September in 1874, he died on Friday 13th July 1951 at 13 minutes to midnight. He is said to have predicted his death on this day as it was the first Friday 13th in his 76th year (7 + 6 = 13).
§ An amazing number of serial killers’ names have 13 letters – Charles Manson, Wayne Williams, Pee Wee Gaskins, Thierry Paulin, Fritz Haarmann, John Wayne Gacy, Michael Swango, Theodore Bundy, Herbert Mullin, Jack the Ripper, Harold Shipman, Frederick West, and Peter Sutcliffe, are just 13 of them.
This comes from an article I first wrote a couple of years ago. A version of it was published in Ireland's Own in June last year. Another version is for sale at http://www.constant-content.com/MoreDetails/81155-Facts_About_Friday_13th.htm .