Gregorian calendarThe Gregorian calendar is the calendar used in most parts of the world. It went into effect in October 1582 following the papal bull Inter gravissimas issued by Pope Gregory XIII, which introduced it as a modification of, and replacement for, the Julian calendar. The principal change was to space leap years differently so as to make the average calendar year 365.2425 days long, more closely approximating the 365.2422-day 'tropical' or 'solar' year that is determined by the Earth's revolution around the Sun.
Baháʼí lawsBaháʼí laws are laws and ordinances used in the Baháʼí Faith and are a fundamental part of Baháʼí practice. The laws are based on authenticated texts from Baháʼu'lláh, the founder of the Baháʼí Faith, and also includes subsequent interpretations from ʻAbdu'l-Bahá and Shoghi Effendi, and legislation by the Universal House of Justice. Baháʼí law is presented as a set of general principles and guidelines and individuals must apply them as they best seem fit.
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.
Calendar eraA calendar era is the period of time elapsed since one epoch of a calendar and, if it exists, before the next one. For example, it is the year as per the Gregorian calendar, which numbers its years in the Western Christian era (the Coptic Orthodox and Ethiopian Orthodox churches have their own Christian eras). In antiquity, regnal years were counted from the accession of a monarch. This makes the chronology of the ancient Near East very difficult to reconstruct, based on disparate and scattered king lists, such as the Sumerian King List and the Babylonian Canon of Kings.
RidvánRiḍván (رضوان ; Persian transliteration: Rezván, ɾezvɒːn) is a twelve-day festival in the Baháʼí Faith, commemorating Baháʼu'lláh's declaration that he was a Manifestation of God. In the Baháʼí calendar, it begins at sunset on the 13th of Jalál, which translates to the 20th or 21st of April, depending on the date of the March equinox (exactly one month on the Gregorian calendar after the equinox). In 2023 it will be celebrated on 21 April. On the first, ninth and twelfth days of Ridván, work and school should be suspended.
EpochIn chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided by congruity, or by following conventions understood from the epoch in question. The epoch moment or date is usually defined from a specific, clear event of change, an epoch event. In a more gradual change, a deciding moment is chosen when the epoch criterion was reached.
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.
CalendarA calendar is a system of organizing days. This is done by giving names to periods of time, typically days, weeks, months and years. A date is the designation of a single and specific day within such a system. A calendar is also a physical record (often paper) of such a system. A calendar can also mean a list of planned events, such as a court calendar or a partly or fully chronological list of documents, such as a calendar of wills. Periods in a calendar (such as years and months) are usually, though not necessarily, synchronized with the cycle of the sun or the moon.
Solar calendarA solar calendar is a calendar whose dates indicate the season or almost equivalently the apparent position of the Sun relative to the stars. The Gregorian calendar, widely accepted as a standard in the world, is an example of a solar calendar. The main other types of calendar are lunar calendar and lunisolar calendar, whose months correspond to cycles of Moon phases. The months of the Gregorian calendar do not correspond to cycles of the Moon phase.
NowruzNowruz (نوروز noːˈɾuːz) is the Iranian or Persian New Year celebrated by various ethnicities worldwide. It is a festival based on the Iranian Solar Hijri calendar, on the spring equinoxon or around 21 March on the Gregorian calendar. The day of Nowruz has its origins in the Iranian religion of Zoroastrianism and is thus rooted in the traditions of the Iranian peoples; however, it has been celebrated by diverse communities for over 3,000 years in Western Asia, Central Asia, the Caucasus, the Black Sea Basin, the Balkans, and South Asia.
