Thursday, April 13th was the 280th anniversary of the birth of Thomas Jefferson. Or was it? Jefferson’s personally designed tombstone states he was born April 2, 1743 O.S. Just what does that mean? Our third President was born before the United States began using the Gregorian calendar (first introduced in 1582), when we were still using the Julian calendar – what came to be known as the “Old Style” calendar, thus the O.S, after his date. 

The Gregorian calendar, also known as the Western or Christian calendar, is the most widely used calendar in the world today. Its predecessor, the Julian calendar, was replaced because it did not correctly reflect the actual time it takes the Earth to circle once around the sun, known as the tropical year. In the Julian calendar, a leap day was added every four years, which it too frequent. Although it is not perfect either, today’s Gregorian calendar used a much more accurate rule for calculating leap years.

Most of us still assume that a leap year occurs every 4 years in our current Gregorian calendar. However, this is inaccurate. The “official rules” are:

  • The year must be evenly divisible by 4.
  • The year can also be evenly divided by 100, it is not a leap year; unless…
  • The year is also evenly divisible by 400. Then it is a leap year.

So, 2000 was a leap year, but 2100 will be skipped to keep our calendar nearly correct.

It’s all a matter of time.

We will be tracking legislative and political happenings in Florida until our next edition. Please reach out to us with any questions or comments.