A couple of posts ago, we saw that by the late 1500s the Julian calendar was seriously off. How to fix it?
A doctor, Aloysius Lilius, thought there were too many leap years. The Julian calendar adds a day—February 29th—every 4 years, no exceptions. What if on some leap years we didn’t add the extra day? His idea was that any leap year that ends in 00—unless it can be divided by 400—gets no extra day.
That would solve the problem! Pope Gregory XIII liked the idea so much he made it official on February 24, 1582. Later that year, ten days disappeared! October 4th was followed by October 15th in order to reset the calendar. The new calendar is called the Gregorian calendar. We still use it today.
The last year that ended in 00 was 2000. Because it can be divided by 400, it was a leap year with February 29 added. The next one will be 2100—it will be a common year with no extra day. I’ve been cutting out the fatty snacks so maybe I’ll live to see that happen.
Here’s the inside-baseball, blow-by-blow account of how the new calendar was adopted by Pope Gregory: http://www.newadvent.org/cathen/09247c.htm
Back to the beginning of The Western Civ User’s Guide to Time & Space
Have a blessed Good Friday!