History Series: Leap Year
History of Leap Year
The Leap Day, February 29, depicts a day that occurs only once every four years, every Leap Year or intercalary year when an extra day is inserted into the calendar. But not every fourth year; if that year ends in “00,” like 1900, then it is not a Leap Year. Except if that year ending in 00 is also divisible by 400, then it is a Leap Year. Unless it is a Tuesday and it is dark. OK, I made up that last rule.
So, years like 2024 are Leap Years, being divisible by 4. But 1900 is not a Leap Year, as it ends in 00. In the year 2000, you’ll remember the famous Y2K, when computer programmers only obeyed the first two rules and assumed that it wasn’t a Leap Year, so all the computers failed, and the world came to an end. That was a Leap Year, as it was divisible by 4, and though it ended in 00, it was divisible by 400 (indeed, it’s divisible five times, if you’re still with me.)
Calculation Correction for Leap Year
How did we get into this calculation conundrum? It has to do with a cumulative rounding error in trying to reconcile the Julian calendar with the tropical or astronomical calendar. The Julian calendar, established by Julius Caesar in 46 B.C., lasted from 45 B.C. until A.D. 1582 and stipulated that the year should be 365 days for three years in a row, with every…
