The 29th of February, or Leap Day, is a date that only comes around every 4 years. The reason for the extra day is fairly straightforward. While a standard calendar year is 365 days long, it actually takes around 365 days and 6 hours for the Earth to revolve around the Sun. Because of this, every 4 years, an extra 24 hours is added to the shortest month of the calendar.
The additional day dates back to 45 BC with the adoption of the Julian Calendar, the Roman calendar named for its architect Julius Caesar. This calendar quickly became the primary calendar used throughout the entire Roman Empire, and remained in use until 1582 when the modern Gregorian Calendar was introduced.
Leap years are still included in the Gregorian Calendar, except in years that are exactly divisible by 100. They are still included in years that are divisible by 400, however. This change was designed to slightly shorten the average year, to ensure the equinoxes occur at roughly the same date and time every year.
Leap Day has persisted in popular culture, due to local traditions as well as serving as a major plot point for many stories throughout history.
Leap Year in Pop Culture:
- Pirates of Penzance: Frederic, the main character of the classic opera Pirates of Penzance, was born on Leap Day. This becomes a major plot point, as Frederic is supposed to remain an apprentice until his twenty-first birthday – which would not technically happen for 63 more years.
- Leap Year (2010): The 2010 romantic comedy starring Amy Adams is based around an old Celtic tradition where women propose marriage to their boyfriend on Leap Day.
- Leap Day William: This irreverent take from the sitcom 30 Rock transforms Leap Day into a holiday, complete with its own absurd mythology. In the fake tradition, every Leap Year, the jolly Leap Day William leaves his home in the Marianas Trench to trade tears for candy.