How many days are in a year? 365, of course, except when we add a leap day every four years.
Well, not anymore.
It takes Earth about 365.2422 days to revolve around the sun. So Julius Caesar rounded up to 365.25, or 365¼, says the U.S. Navy Observatory. Then he added one extra day to the 365-day calendar year every four years, because it took four years for that extra quarter of a day to add up to one full day.
But by rounding, Caesar added about 11 minutes to the calendar year – which really added up eventually. By the time Pope Gregory XIII came along at the end of the 1500s, the calendar year was 12 days ahead of the solar year, which means the beginning of seasons had shifted forward by 12 days.
Ol’ Greg decided to omit the leap year three times every 400 years. So instead of 365 days with a day added every four years, it’s really done only 97 times every 400 years. Got that?
And in case you need any extra trivia to make it through your extra day this year…
- The idea of leap days entered Western culture via Egypt. The ancient Egyptians were among the first civilizations to determine the true length of the solar year and adopted a calendar with an extra day every four years, says National Geographic. Julius Caesar was introduced to the system through his lover Cleopatra. Pope Gregory XIII later improved upon the Julian system, giving us the Gregorian calendar that most of the world uses today.
- The Gregorian calendar year is 365.2425 days long. “This agrees to within a half a minute of the length of the [solar] year,” says the U.S. Navy Observatory. “It will take about 3,300 years before the Gregorian calendar is as much as one day out of step with the seasons.”
- The Gregorian calendar omits those three leap years every 400 years on centurial years. For example, 2000 was a leap year, so 2100, 2200, and 2300 will not be. Remember it this way: Centurial years that are not divisible by four are not leap years.
- According to legend, it’s accepted for women to propose to men on Leap Day. And men must accept, according Western Kentucky University librarian Lynn Niedermeier.
- Leap years give us an extra day to do our taxes. But they don’t affect Lent. While taxes are always due on April 15, Lent always begins 40 days before Easter.
- The leap year could mean an extra paycheck. As the American Payroll Association explained it to the Wall Street Journal: “While most years are 52 weeks long plus one day, leap years have 52 weeks and two extra days. Since December will include an extra Sunday and Monday this year, employees whose paydays fall on either of those days will get an extra check in 2012, even though their pay rate remains the same.”
- The leap year could also mean a pay cut. “To compensate for the extra payday, companies will likely reduce salaried individual paychecks throughout the year to ‘pay’ for the extra paycheck,” says the American Payroll Association. “Most salaried individuals are promised an annual salary, not a specific amount each paycheck.”
- Anthony, Texas, is known as the Leap Year Capital of the World. The town’s chamber of commerce administers the Worldwide Leap Year Birthday Club and sponsors a multi-day Worldwide Leap Year Festival – which the town claims is the only such festival in the world. Former chamber member Mary Ann Brown, a Leap Day baby, proposed the club and festival in 1988 when she learned that her neighbor was also a Leap Day baby.
- “Leap Day” is the name of a band. The Netherlands-based progressive rock group was founded on Feb. 29, 2008.
- “Leap Year” is the name of a movie. Released in 2010, the romantic comedy is about a woman who travels to Ireland to propose to her boyfriend on Feb. 29.
- The Disney parks will stay open for 24 hours on Feb. 29, 2012. The event, called One More Disney Day, marks the first time ever that both Disneyland in California and the Magic Kingdom in Florida will stay open for 24 hours.