Feb. 29, 2012 is Leap Day! The day is added every four years to make the calendar have 366 days rather than the common 365 days. But, what is Leap Year and why is a Leap Day added to the calendar?

Scientific Explanation of Leap Day

A Leap Year is a year that contains one additional day in order to keep the calendar year in sync with the seasonal or astronomical year. Leap years are necessary to keep the planet aligned with Earth's revolutions around the sun.

While the calendar assumes the Earth revolves around the sun every 365 days, it actually takes the Earth a bit longer - 365 days, 5 hours, 48 minutes and 46 seconds. If the calendar were not adjusted for the extra six hours by adding an extra day approximately every four years, the calendar would slowly shift and the seasons would no longer be aligned with the traditional months.

Without Leap Days, the calendar would be off by 24 days within 100 years.

How Do You Calculate A Leap Day?

Leap Days occur in most years that are divisible by 4, such as 2004, 2008, 2012, 2016 and 2020. However, Leap Years do not occur in years that are evenly divisible by 100, with the exception of those that are divisible by 400. This means that 1900 was not a Leap Year, but 2000 was!

Origins and History of Leap Day

The Ancient Egyptians were the first to discover the discrepancy between a strict man-made calendar and the shifting seasonal year.

Starting around 45 BCE, Julius Caesar introduced Leap Years by adding one day to the calendar or doubling one day (giving the day the nickname bissextile or twice sixth). In the Roman calendar, February was the last month of the calendar; therefore the extra day was added in February in the Julian calendars.

More precise calculations of the Earth's rotations were determined by the Gregorian calendar in the 16th century. The Gregorian calendar is a modification of the Julian calendar first used by the Romans. In the Gregorian calendar, Leap Years are only those divisible by four, such as 2012, 2016, 2020, 2024.

Leap Day Birthdays

A select few have birthdays on Feb. 29. The chance of being born on Leap Day is 1 in 1,461. For centuries, astrologers believed that children born on Leap Day have unusual talents, unique personalities and even special powers.

Sadly, Leapers or leaplings, the nickname attributed to those born on Leap Day, only celebrate their birthday every four years. The leaplings may celebrate their birthday on Feb. 28 or Mar. 1 instead, but most states in the U.S. will only legally recognize the person as their next age on Mar. 1 of the year.

Among others, rapper Ja Rule (1976), model and actor Anthonio Sabato Jr. (1972), motivational speaker Tony Robbins (1960) and Italian opera composer Gioacchino Rossini (1792) were born on Leap Day.

Women Can Pop The Question... But Only Once Every Four Years

Historically, Feb. 29 has been the one day of the year where women can traditionally propose marriage to a male companion. While the exact history of the strange tradition is unknown, many speculate the tradition began in the 5th century in Ireland when St. Bridget complained to St. Patrick of the unfairness that women had to wait for men to propose. St. Patrick gave in to St. Bridget's wishes and set aside Feb. 29 as the one day when women could ask for a man's hand in marriage.

The odd marriage proposal tradition continued in Scotland. Queen Margaret supposedly declared in 1288 that a woman could propose to any man she liked on Feb. 29. According to the declaration, men who refused the proposal would need to pay a fine in the form of a kiss, a silk dress, a pair of gloves or even a monetary fine of one pound.

Although the folk tradition may be rooted in history, many women plan to pop the question to their lover this year on Leap Day. The day has unofficially become known as Sadie Hawkins Day in tribute to the comic strip Li'l Abner that first popularized the idea of a day for gender role-reversal, when girls could initiate a date -- unheard of before 1937.

Strange Leap Day Facts and Traditions

1. In addition to the strange marriage proposal tradition, Leap Day is often celebrated in contemporary cities with special deals and discounts, particularly with dishes that include frog legs. Indulge in the crunchy amphibians this Leap Day!

2. The official Leap Day cocktail will also be enjoyed in bars around the world. According to CheapSally.com, the official Leap Year cocktail is 2 ounces gin, ½ ounce Grand Marnier, ½ ounce sweet vermouth, and ¼ ounce fresh lemon juice. The parts are stirred together and strained into a chilled cocktail glass.

3. While Leap Year may be shunned by children who suffer from the rare chance to celebrate their birthday, the Playboy franchise remembers the day proudly. Hugh Hefner opened the first Playboy Club in Chicago, Ill. on Leap Day in 1960.

4. In 2012, 56 countries are recognizing Leap Day as Rare Disease Day. The nations participating in the awareness day are calling for increased research and funding for diseases and ailments that have no known cure.

5. Despite the rare chance of being born on Leap Day, Karin Henriksen of Norway holds the world's record for giving birth to the most children on consecutive Leap Days. She has given birth to three children on consecutive Leap Days, including her daughter on Feb. 29, 1960 and her two sons on Leap Day in 1964 and 1968.

6. In addition, the record for the most generations born on Leap Day is held by the Keogh family in Ireland and Great Britain. The Keogh father, Peter Anthony, was born on Leap Day in 1940 in Ireland, his son, Peter Eric, in 1964 in the UK and the granddaughter, Bethany Wealth, on Leap Day in 1996.

7. Workers who have fixed annual or monthly wages essentially work for free on Feb. 29 because added wages are not usually calculated to account for the additional day.

8. Reuters reports that there are more than 200,000 leaplings in the United States and more than 5 million worldwide.

Enjoy Leap Day this year as there won't be another for 1,461 days!

Related Article:  Leap Year 2012: My Sixth Birthday in Photos [SLIDESHOW]