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Treebeard's Stumper Answer
28 Feb 97

Sometimes we celebrate birthdays when it's convenient rather than official. It's convenient to arrange a three day weekend, so we had Washington's Birthday (observed) on Feb. 17, even though his actual birthday is Feb. 22 according to the calendar. The stumper is that George Washington was really born on February 11 according to his own calendar. Why is there a discrepancy of 11 days about a simple matter of historical fact?

Washington's birthday is a tangled tale of politics, religion, and science. The Earth takes 365.24219 days (more or less) to orbit the sun. The old Julian Calendar adds a leap day every 4 years for an average year of 365.25 days. This is a bit too much, adding an extra day every 128 years. By the 1500's, the equinox had shifted 10 days, so Pope Gregory changed the leap year rule and simply cut 10 days.

Britain (and the US as a British colony) resisted the Church on principle until 1752, when Sep. 2 was followed by Sep. 14, now 11 days dropped instead of 10 since another 128+ years had passed. September 10, 1752 would be a fine time to set an alternate-history sci-fi story!

Washington was born on Feb. 11 (Julian), but the missing eleven days bring this to Feb. 22 (Gregorian).

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Marc Kummel / mkummel@rain.org