What are the types of calendars? The motion (or apparent mot | Ask Me

What are the types of calendars?

The motion (or apparent motion) of the Sun and the Moon provide temporal cycles which have strongly influenced the design of most calendars.

Most calendars usually attempt to accord either with the solar cycle (the cycle of the seasons) or with the lunar cycle (the cycle of the phases of the Moon) or with both.

There are over forty calendars currently in use, and many others that have been used or have been invented.

Calendars thus come in many forms and, according to specialists, may be divided into five kinds:

Purely lunar calendars
Those which are based on the natural cycles of the Moon, which have months which attempt to stay as closely as possible in sync with the lunar phases, and whose years (composed of months) have no close relation with the solar cycle. A good example of this type is the Muslim Calendar.

Purely solar calendars
Those which are based on the cycle of the seasons, which results from the motion of the Earth around the Sun (and the fact that the Earth's axis of rotation is tilted significantly with respect to the Earth's plane of rotation about the Sun). These calendars have years, which accord with the seasonal cycle and begin at or near a fixed point in that cycle (for example, the vernal equinox). Years in a purely solar calendar may be composed of months, but the months have little if any connection with the lunar cycle, for example, the the Gregorian Calendar (Common Era Calendar with years designated according to the astronomical system) commonly in use today.

Lunisolar calendars and Solilunar calendars
These calendars aim to be both solar calendars and lunar calendars.
Lunisolar calendars are more successful in tracking the seasonal cycle than the lunar cycle. Such a calendar consists of years which accord closely with the seasonal cycle and months which accord more-or-less closely with the lunar cycle. An example of a lunisolar calendar is the Hindu calendar.
Solilunar calendars are more successful in tracking the lunar cycle than the seasonal cycle. They consist of months which accord closely with the lunar cycle and years which accord more-or-less closely with the seasonal cycle, for example, the Chinese Calendar or the Hebrew Calendar.
Usually solilunar calendars and lunisolar calendars are regarded as forming a single class: 'lunisolar calendars'.

Lunistellar calendars
Some experts suggested that a classification of calendars should also include the category of 'lunistellar'. The Egyptian Calendar is considered to be such a calendar.

Other calendars
Some calendars apparently make little or no attempt to accord with the cycles of the Moon or of the Sun. For example, the Tzolkin and the Long Count in the Maya Calendar. Some of these calendars may accord with other astronomical cycles, such as that associated with the planet Venus.