### Question

Is it true that in the late 1800's they took away or added 11 days to the calendar that didn't exist?

Even your grandfather can't be old enough to remember when 10 days were removed from our calendar! This happened in 1582 A.D. when the current Gregorian calendar we now use was established. At that time, in order to make up for inaccuracies in earlier calendars, Pope Gregory XIII decreed that 10 days would be 'lost' when the new calendar went into effect. This upset quite a few people at the time, who protested 'Give us back our 10 days!'

In order to accommodate the fact that one year does not have an exact number of full days in it, a leap day is added every 4 years to try to keep things synchronized. That trick helps, but still leads to minor errors that must be further corrected by SKIPPING leap day 3 times every 400 years. In the Gregorian calendar, this is done by NOT having a leap day on years ending in 00 when the first two digits are NOT divisible by 4. The years 1700, 1800, and 1900, for example, were NOT leap years because 17, 18, and 19 are not divisible by 4. The year 2000 IS a leap year because 20 IS divisible by 4.
Answered by: Paul Walorski, B.A. Physics, Part-time Physics Instructor

There's a bit more to the story. Since Pope Gregory's decree occurred after the Protestant Reformation, the Great Schism (Eastern Orthodox) and formation of the East Anglican Church of England, not everybody changed their calendars at the same time. Czarist Russia never did, so their change didn't occur until after the revolution of 1917. For a long while it was possible to 'time travel' in Europe, going from one village to another where it was 10 (and later 11) days earlier or later.
Answered by: Tom Swanson, PhD. Physics, Oregon State U.

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