If you walk under a ladder after breaking a mirror, does that make your day doubly unlucky? Since we’re a science program, we’ll say no. But that double-trouble philosophy underpins the superstitions about Friday the 13th. Both Friday and the number 13 have been considered bad luck. Put them together, and you have what may be the most feared of any day-and-date combo.

The individual superstitions both have religious and mythological origins. In Christianity, for example, the Last Supper was shared by 13 men. And Jesus was crucified on a Friday.

Just when the two were put together isn’t clear. The idea of Friday the 13th being unlucky shows up in some publications in France in 1834. The first record of it in the United States dates to 1882.

How many people fear the date isn’t clear, either. But scientists have come up with a couple of names for it. The shorter one, believe it or not, is friggatriskaidekaphobia. Frigg was the Norse goddess for whom Friday is named, and triskaidekaphobia is fear of the number 13.

Other than some unlucky teens in the “Friday the 13th” movies, there’s no evidence that the day is any more dangerous than any other. A study in 2011 compared hospital records for 13 Fridays the 13th to other date combinations. There was no bump in the number of emergency-room visits – nothing unlucky about Friday the 13th.

Script by Damond Benningfield