Año bisiesto

Año Bisiesto or Leap Year is a year that is exactly divisible by 4, except for end-of-century years which must be divisible by 400. This means that the year 2000 was a leap year, although 1900 was not. This extra day, February 29, is added to the calendar during leap years. This adjustment is necessary because the Earth does not orbit around the sun in precisely 365 days.

History

The concept of the leap year has been around for over 2000 years. It was first introduced by Julius Caesar in the Julian Calendar in 45 BC. The system was refined by Pope Gregory XIII in 1582 with the introduction of the Gregorian Calendar, which is the calendar system currently in use today.

Calculation

The calculation for determining whether a year is a leap year or not is as follows:

• If the year is evenly divisible by 4, it is a leap year.
• However, if that year is also evenly divisible by 100, it is not a leap year, unless...
• The year is also evenly divisible by 400. Then it is a leap year.

This means that the year 2000 was a leap year, while 1900 was not.

Leap Day

Leap Day is the extra day added during a leap year. It is added after February 28, making the leap year February 29 days long. This day is added to keep our calendar year synchronized with the solar year.

Cultural Significance

In many cultures, there are traditions and superstitions associated with leap years and especially Leap Day. For example, in some cultures, it is considered acceptable for a woman to propose marriage to a man on Leap Day.

See Also

• Julian Calendar
• Gregorian Calendar
• Leap Day