Lunar calendarA lunar calendar is a calendar based on the monthly cycles of the Moon's phases (synodic months, lunations), in contrast to solar calendars, whose annual cycles are based only directly on the solar year. The most widely observed purely lunar calendar is the Islamic calendar. A purely lunar calendar is distinguished from a lunisolar calendar, whose lunar months are brought into alignment with the solar year through some process of intercalation - such as by insertion of a leap month.
MonthA month is a unit of time, used with calendars, that is approximately as long as a natural orbital period of the Moon; the words month and Moon are cognates. The traditional concept arose with the cycle of Moon phases; such lunar months ("lunations") are synodic months and last approximately 29.53 days, making for roughly 12.37 such months in one Earth year. From excavated tally sticks, researchers have deduced that people counted days in relation to the Moon's phases as early as the Paleolithic age.
Orbital periodThe orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets, exoplanets orbiting other stars, or binary stars. It may also refer to the time it takes a satellite orbiting a planet or moon to complete one orbit. For celestial objects in general, the orbital period is determined by a 360° revolution of one body around its primary, e.
Malayalam calendarThe Malayalam Calendar is a sidereal solar calendar used in Kerala. The origin of the calendar has been dated to 825 CE, the beginning of the Kollam Era. There are many theories regarding the origin of the era, but according to recent scholarship, it commemorated the foundation of Kollam after the liberation of the southern Chera kingdom (known as Venadu) from the Chola dynasty's rule by or with the assistance of the Chera emperor at Kodungallur.
List of calendarsThis is a list of calendars. Included are historical calendars as well as proposed ones. Historical calendars are often grouped into larger categories by cultural sphere or historical period; thus O'Neil (1976) distinguishes the groupings Egyptian calendars (Ancient Egypt), Babylonian calendars (Ancient Mesopotamia), Indian calendars (Hindu and Buddhist traditions of the Indian subcontinent), Chinese calendars and Mesoamerican calendars. These are not specific calendars but series of historical calendars undergoing reforms or regional diversification.
Sidereal yearA sidereal year (saɪˈdɪəri.əl, USalsosɪ-; ), also called a sidereal orbital period, is the time that Earth or another planetary body takes to orbit the Sun once with respect to the fixed stars. Hence, for Earth, it is also the time taken for the Sun to return to the same position relative to Earth with respect to the fixed stars after apparently travelling once around the ecliptic. It equals 365.256 363 004 ephemeris days for the J2000.0 epoch.
Rumi calendarThe Rumi calendar (رومی تقویم, Rumi takvim, lit. "Roman calendar"), a specific calendar based on the Julian calendar, was officially used by the Ottoman Empire after Tanzimat (1839) and by its successor, the Republic of Turkey until 1926. It was adopted for civic matters and is a solar based calendar, assigning a date to each solar day. In the Islamic state of the Ottoman Empire, the religious Islamic calendar was in use, within which days are numbered within each lunar phase cycle.
Early Germanic calendarsThe early Germanic calendars were the regional calendars used among the early Germanic peoples before they adopted the Julian calendar in the Early Middle Ages. The calendars were an element of early Germanic culture. The Germanic peoples had names for the months that varied by region and dialect, but they were later replaced with local adaptations of the Julian month names. Records of Old English and Old High German month names date to the 8th and 9th centuries, respectively. Old Norse month names are attested from the 13th century.
Holocene calendarThe Holocene calendar, also known as the Holocene Era or Human Era (HE), is a year numbering system that adds exactly 10,000 years to the currently dominant (AD/BC or CE/BCE) numbering scheme, placing its first year near the beginning of the Holocene geological epoch and the Neolithic Revolution, when humans shifted from a hunter-gatherer lifestyle to agriculture and fixed settlements. The current year by the Gregorian calendar, AD , is HE in the Holocene calendar.
Javanese calendarThe Javanese calendar (Pananggalan Jawa) is the calendar of the Javanese people. It is used concurrently with two other calendars, the Gregorian calendar and the Islamic calendar. The Gregorian calendar is the official calendar of the Republic of Indonesia and civil society, while the Islamic calendar is used by Muslims and the Indonesian government for religious worship and deciding relevant Islamic holidays.
