IN 1582, 10 DAYS TOTALLY DISAPPEARED.  The calendar went like this:

 

Mon. Oct. 1, 1582

Tues. Oct. 2, 1582

Wed. Oct. 3, 1582

Thur. Oct. 4, 1582

Fri. Oct. 15, 1582

Sat. Oct. 16, 1582

Sun. Oct. 17, 1582

Why?  The calendar was slowly “gaining time.”  The Earth revolves around the sun only 365.242 days a year, not 365.250.  This change made by Pope Gregory XIII allowed seasons to fall back into a “regular pattern.”

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So what exactly happened?  Buckle up for a few details.

(1)  The Julian Calendar was in force for centuries before Oct. 4, 1582.

(2)  The Julian calendar made each year a tad bit (0.008 days) longer on paper.  If this went on many, many more years the seasons as we know them would be “out of place” on the calendar.

(3)  So, making October 1582 a 21-day month, tossing out 10 days, would “restore order” to the calendar and, to keep the calendar from getting out of whack again a few centuries down the road, leap years would continue (adding one day to February every fourth year) except on year designations that could be divided by 100 (1900, for example) unless they could also be divided by 400 (2000, for example, would remain a leap year, as it did).

(4)  Note that Oct. 15 was “Friday” following the “Thursday” on Oct.4.  Hence the 7-day week pattern of days was not modified.  (Incidentally, the 7-day pattern goes back to…I have no idea when.  Anybody know?)

(5)  All these changes resulted in a new “Gregorian” calendar, which superseded the very similar Julian one.  An interesting piece of history is that many countries didn’t accept these changes at first.  Think of the confusion!

(6)  Also in 1582 Shakespeare married Anne Hathaway.  What does this have to do with Points 1 – 5?  Absolutely nothing.  Time to stop…