Origins - Where did Calendars Begin?
calendars began with people recording time by using natural cycles:
days, lunar cycles (months), and solar cycles (years).
year is 365 days 5 hours 48 minutes 46 seconds long or 365.242199
time between full moons is 29.53 days.
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.
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).
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).
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