Oct. 8, 1582: Nothing Happens ... in Catholic Lands

"1582: Nobody does anything, anything at all. In fact, nobody does anything whatsoever between Oct. 4 and Oct. 15, 1582, because the 10 intervening days have simply been declared out of existence by the pope. (This offer may not apply outside Italy, Spain and Portugal.)

Where did those days go?

By the mid-1570s, the Julian Calendar established in 45 B.C. was 10 days behind the real seasons of the year. The spring equinox was actually occurring on March 12 or thereabouts, and Easter (set by a formula based on an arbitrary March 22 equinox date) was falling too late in the real springtime.

All this happened because the Earth year is about 11 minutes short of the 365¼ days set by Julius Caesar. It's really 365 days, 5 hours, 48 minutes, 46 seconds. If the drift kept up, Easter would eventually have been observed in the summer, and Christmas in the spring.

So Pope Gregory XIII appointed a commission to tweak the Julian Calendar. Under the leadership of physician Aloysius Lilius and Jesuit astronomer Christopher Clavius, the commission consulted with scientists and clergy. After wrestling with various ideas for half a decade, the commission proposed eliminating three leap years in every 400 (years ending in 00, unless they are divisible by 400).

That would prevent further creep of the calendar against the seasons (except for a minuscule under-correction). But resetting the calendar so the equinox would come in late March needed a more drastic solution: 10 days would have to be skipped, erased, eradicated, obliterated, wiped out of existence.

The commission sent its report to the pope Sept. 14, 1580. He issued a papal bull on Feb. 24, 1582, declaring that the new calendar would go into force in October (when there were few holy days), and that 10 days would be skipped. The day after Oct. 4 would be called not Oct. 5, but Oct. 15."

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