Know It All: Leap Day

Despite what our elementary teachers told us, a year isn't really 365 days. Our planet actually takes 365 1/4 days to revolve around the sun. These six additional hours each year add up to an extra 24 hours over four years, at which point we add a day to our calendar in order to keep us in sync with the sun. Without leap day, annual events would slowly shift seasons—eventually, we'd be celebrating Christmas in July.

While the first leap day was likely observed by the Egyptians, Caesar is credited for incorporating a leap year into the Julian calendar in 46 B.C. However, scientists noticed that annual events were still shifting over extended periods of time. While the calculation of 365 1/4 days for the Earth to lap the sun was close, the true figure is actually about 11 minutes short of that, and this tiny miscalculation caused a day of discrepancy every 128 years. Pope Gregory XIII came to the rescue in 1582, ruling that leap year would be skipped three times every four centuries to fix the snag.

Though the point of a leap day is to keep our calendar aligned with nature, hundreds of years ago people thought that messing with our months would throw Mother Nature for a loop. Farmers worried that the change would lower crop yields and sicken livestock. In fact, a Scottish saying declared that leap year was never a good sheep year. Lore also held that leap day babies were unruly and tough to raise. (Maybe we should ask J.Lo—whose twins were born on Feb. 29, 2008—if this adage proves true.)

Speaking of leap day babies, those born on Feb. 29 are called leaplings or leapers. Since their actual date of birth only comes around a quarter of the time, leaplings often celebrate non–leap year birthdays on Feb. 28 or March 1. Legal permissions like getting a driver license or drinking alcohol are granted on whichever day a particular region deems official. Most U.S. states test leaplings' patience by making them wait until the 1st.

Rapper Ja Rule and actor Antonio Sabato Jr. are among the roughly 187,000 leaplings in the U.S. and 4 million worldwide. Long-expired leaplings include poet John Byrom, bandleader Jimmy Dorsey and writer Dee Brown. The likelihood of being born on Feb. 29 is roughly 1 in 1,500, and on leap day 2012, approximately 10,000 American babies will enter this exclusive minority.

Four hundred years ago, women weren't allowed to propose marriage to men… except on leap day. While the source of this switcheroo isn't 100 percent clear, folklore traces the tradition to fifth-century Ireland, when St. Bridget supposedly complained to St. Patrick that gals were sick of waiting around for their procrastinating men to pop the question. Patrick consented to a leap day role reversal and, by some accounts, also declared that men who declined the proposal would be fined!

In 1999, a rumor spread that the year 2000 would include not only a Feb. 29, but also a Feb. 30. While the millennium theory was merely a hoax, a double leap day actually happened in 18th-century Sweden. After the country attempted to gradually switch from the Julian to the Gregorian calendar in the 1700s (to follow the lead of other European countries), the plan went awry and the decision was temporarily reversed. In order for the Swedes to revert back to the Julian system, they had to add Feb. 29 and 30 to their 1712 calendar.