Calendars

Julian Calendar

Over a 400-year cycle, the calendar dates vary by as much as 2.25 days, but they vary predictably and periodically. Overall, the error is cyclic, not cumulative. This calendar, decreed by Pope Gregory XIII, became known as the Gregorian calendar rather than the Lilian calendar. The Gregorian calendar was eventually adopted by all European nations, although not without struggles, and even by Egypt, China, Korea, and Japan (with modifications for the latter three). Some nations adopted this calendar as early as 1582, while others adopted it only in the 1920s.

Gregorian Calendar

Over a 400-year cycle, the calendar dates vary by as much as 2.25 days, but they vary predictably and periodically; overall, the error is cyclic, not cumulative. This calendar, decreed by Pope Gregory XIII, became known as the Gregorian calendar rather than the Lilian calendar. (They just use your mind and they never give you credit. It’s enough to drive you crazy if you let it.) The Gregorian calendar was eventually adopted by all European nations, although not without struggles, and even by Egypt, China, Korea, and Japan (with modifications for the latter three). Some nations adopted this calendar as early as 1582, while others adopted it only in the 1920s.