Western Gregorian calendars have a leap day added in February every 4 years. Other cultures add days, and even months, to their calendars to account for leap days. These leap days, or months, though, do not necessarily coincide with ours, happen on the same month, or even occur every four years.
Why we Need A leap Year Added to Our Calendar
A leap year needs to be added to our modern Gregorian calendar every 4 years to keep the calendar accurate and in alignment with the Earth's rotation around the sun. Our planet earth takes approximately 365.242199 days to make a complete orbit. This means we would loose about 6 hours every year without a leap day. This doesn't sound like much, but after 124 years, our calendar would otherwise be off by 30 days, or a whole month.
The Iranian Leap year is More Accurate
The Iranian calendar adds a day to the last day of the year every 4 years, as does the Gregorian calendar. After every 6 or 7 leap years, though, the leap day occurs on the fifth year, not the forth, meaning that there are 8 leap years every 33 years.
The result of this calculation is that a more accurate calendar is produced. The Gregorian calendar is off by one day every 3226 years. The Iranian calendar needs to be corrected by one day every 141,000 years. Though none of us will be around to see either calendar need to be corrected, it is, nonetheless, an interesting fact.
Chinese Leap Years Are The Most Unpredictable
The Chinese calendar is a lunisolar calendar, meaning that it is based on lunar cycles, but adds months to the year to keep in line with solar calendars. This means that a Chinese leap year calendar contains an extra month, for a total of thirteen. The term used for adding days or months to a lunar calendar to keep it in line with seasons and leap years is intercalation.
The intercalary month of the leap year in the Chinese calendar varies not only from month to month, but year to year. The Chinese leap year is determined by the number of new moons from the 11th month of one year to the 11th month of the next. If there are 13 new moons during this time frame, this is a leap year, and an extra month is inserted into the calendar. Since the Chinese calendar is considered to have been the most uninterrupted and accurate over the last 4 000 years, the use of intercalation in a calendar to calculate a leap year is the most accurate, but also the most confusing.
The Simple Ethiopian Calendar
The Ethiopian calendar is the easiest to understand. It is based on the Julian calendar (the calendar before the Gregorian) and the Coptic Egyptian calendar. Each month in Ethiopia has 30 days. The thirteenth month has 5 days in a regular year, and 6 in a leap year.
The Gregorian calendar does not count a leap year during the turn of a century, unless it is divisible by 400. The Ethiopian calendar has a leap year every four years, irregardless of math equations or lunar cycles. Though probably the easiest to understand, the Ethiopian leap year, and their calendar, is the least accurate.
So, having looked at each system, which would you prefer to live with?
Sources:
www.timeanddate.com/date/leap-day.html
www.infoplease.com/spot/leapyear1.html
www.chinapage.com/astronomy/calendar/calendar.html
Ian Shoust - With a degree in Communications and a certificate in Digital Video Editing, Ian Shoust has worked as a freelance videographer, editor, and ...
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