January 4, 2016 - In case you have not noticed, 2016 is a leap year. Why do we need leap years anyway? The short answer is, “the leap years synchronize the calendar year with the solar year”. However, leap years are far more complicated than that simple answer.
The Gregorian calendar, which now serves as the standard calendar for civil use throughout the world, has both “common years” and “leap years”. A common year has 365 days while the leap year has 366 days, with the extra day designated as February 29.
A leap year occurs every four years to help synchronize the calendar year with the solar year, or the length of time it takes the earth to complete its orbit about the sun, which is 365.25 days. The length of the solar year, however, is slightly less at 365.242216 days, or by about eleven minutes. To compensate for this discrepancy, the leap year is omitted three times every four hundred years.
Now, here is where it gets a little confusing. A century year cannot be a leap year unless it is divisible by 400. Thus, 1700, 1800, and 1900 were not leap years, whereas 1600, 2000, and 2400 are leap years.
Being off by eleven minutes may not seem like a lot, but over the course of centuries it added up until in the 16th century, the vernal equinox was falling around March 11th instead of March 21st. In 1582 Pope Gregory XIII adjusted the calendar by moving the date ahead by 11 days and by instituting the exception to the rule for leap years. This new rule, whereby a century year is a leap year only if divisible by 400, changed the average length of the year to 365.2425 days which is much closer to the solar year.
Now that we have cleared up the reason for leap years, what are your chances of being born on leap day? Statistics say your chances are about 1 in 1,500.
If you were born on a leap day, when is your birthday? Do you get your driver’s license on February 28th or March 1st? It is an ambiguous question that is decided by each state. Most states, however, consider March 1st as the official day.
Ever wonder how many people were born on leap day? There are about 187,000 people in the United States, and four million people in the world who were born on February 29th.
No calendar is perfect. To make a calendar a better measure of the Earth’s orbit, leap years were created. The final result is that 97 years out of every 400 are leap years, giving the total number of leap days as 146,097. So if you were born on February 29th, you are a special person belonging to a unique private club. Happy Birthday!
