1. Leap days are necessary to keep our calendar in alignment with the Earth's actual trips around the sun. The actual journey takes us 365 days, 5 hours, 48 minutes and 45 seconds. If we didn't adjust and add that extra day every 4 years, we'd lose 6 hours every year. After just 100 years, we'd be off-kilter by about 24 days. Another 100 and we'd be off by almost an entire season. You can imagine what chaos would ensue.
2. This Leap Day thing isn't new. Julius Caesar introduced the first leap year back around 46 B.C. His Julian calendar had only one rule: Any year evenly divisible by four would be a leap year. Unfortunately, that math created too many leap years, but it wasn't until Pope Gregory XIII introduced his Gregorian calendar around 1,500 years later that we came up with the current system. So here's how it works There's a leap year every year that is divisible by four, except for years that are both divisible by 100 and not divisible by 400. So the 2000 was a leap year, but the years 1700, 1800 and 1900 were not. According to ScienceWorld, the added rule about centuries was a fix to make up for the fact that an extra day every four years was too much of a correction.
3. Lest you think that we're all on the same page when it comes to Leap Year, you should know that A whole leap month is added to the Chinese calendar every three years. The leap month's place in the Chinese calendar varies from year to year. 2015 was a leap year in the Chinese calendar. A leap year in the Ethiopian calendar occurs when an extra day is added to the last month of the year every four years.
4. It's acceptable for a woman to propose to a man on Feb. 29. The custom has been attributed to St. Bridget, who is said to have complained to St. Patrick about women having to wait for men to propose marriage. Patrick supposedly gave women one day to propose.
5. People born on leap day are often called "leaplings" or "leapers" because I guess "Bob," "Tom," and "Mary" is just too boring. Most folks born on February 29 celebrate their birthday on Feb. 28 or March 1 on non-leap years.
6. The twin cities of Anthony, Texas, and Anthony, New Mexico, are the self-proclaimed Leap Year Capital of the World. They hold a four-day leap year festival each leap year that includes a huge birthday party for all leap year babies.
7. If you were born on leap day, you share a birthday with composer Gioacchino Rossini, motivational speaker Tony Robbins, jazz musician Jimmy Dorsey, actors Dennis Farina and Antonio Sabato Jr., and rapper/actor Ja Rule.
8. Apparently, there's a leap year club: The Honor Society of Leap Year Babies is a club for people born on Feb. 29. More than 10,000 people worldwide are members. I'm assuming that this would exclude any "leapers" from China or Ethiopia since February 29 has no special significance for them.
9. Hollywood has not let us down. There's a leap year movie starring Amy Adams and Matthew Goode. The 2010 romcom "Leap Year" is about a woman who travels to Ireland to ask her boyfriend to accept her wedding proposal on leap day, when tradition says that not only can women ask, but men cannot refuse a woman's marriage proposal.
10. Leap years in history: During leap years, George Armstrong Custer fought the Battle of the Little Bighorn (1876), the Titanic sank (1912), Benjamin Franklin proved that lightning is electricity (1752) and and gold was discovered in California (1848).
So there you go! Now you know.