Calendar Origins

The answers to many questions about calendars

<<Home Calendar Origins Egyptian Calendar>>

Modern Calendar Origins:

Calendar Origins - Where did calendars begin?

Day Name Origins - Where did the Names of Days come from?

Calendar Name Origins - Where did the Names of Months come from?

Months of the Year Origin - Why 12 months in a year?

Why 28 days in February?

Who set the Year 0, AD, BC?

Calendars it Derived From:

Egyptian Calendar

Roman Calendar

Julian Calendar

Calendar Origins - Where did Calendars Begin?

Ultimately, all calendars began with people recording time by using natural cycles: days, lunar cycles (months), and solar cycles (years).

The year is 365 days 5 hours 48 minutes 46 seconds long or 365.242199 days.

The time between full moons is 29.53 days.

Various peoples have attempted to organize these cycles into calendars to keep track of time and to be able to predict future events of importance to them, such as the annual Nile flood in ancient Egypt.

The main problem is that these natural cycles do not divide evenly. So a month measured by the moon doesn't equal an even number of days, and a solar year is not equal to a certain number of moon cycles (months or "moon"ths).

Early people could either try to stay in sync with the moon, perhaps making months alternating combinations of 29 and 30 days, with special rules to resync occasionally with a solar year by adding leap months (such as the Jewish or Chinese calendar) or abandon lunar cycles and concentrate on the solar year (such as the Ancient Egyptian calendar of 12 same-sized months).

If syncing a calendar with lunar cycles is most important, we call it a lunar calendar. If syncing a calendar with the solar year, a solar calendar, and if trying to meet both needs, a lunisolar calendar (such as the Ancient Roman calendar).


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