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As a moveable feast, the date of Easter is determined in each year through a calculation known as (). Easter is celebrated on the first Sunday after the Paschal full moon, which is the first full moon on or after 21 March (a fixed approximation of the March equinox). Determining this date in advance requires a correlation between the lunar months and the solar year, while also accounting for the month, date, and weekday of the Julian or Gregorian calendar. The complexity of the algorithm arises because of the desire to associate the date of Easter with the date of the Jewish feast of Passover which, Christians believe, is when Jesus was crucified. It was originally feasible for the entire Christian Church to receive the date of Easter each year through an annual announcement by the Pope. By the early third century, however, communications in the Roman Empire had deteriorated to the point that the church put great value in a system that would allow the clergy to determine ...
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Easter
Easter,Traditional names for the feast in English are "Easter Day", as in the '' Book of Common Prayer''; "Easter Sunday", used by James Ussher''The Whole Works of the Most Rev. James Ussher, Volume 4'') and Samuel Pepys''The Diary of Samuel Pepys, Volume 2'') as well as the single word "Easter" in books printed i157515841586 also called Pascha (Aramaic, Greek, Latin) or Resurrection Sunday, is a Christian festival and cultural holiday commemorating the resurrection of Jesus from the dead, described in the New Testament as having occurred on the third day of his burial following his crucifixion by the Romans at Calvary . It is the culmination of the Passion of Jesus Christ, preceded by Lent (or Great Lent), a 40-day period of fasting, prayer, and penance. Easter-observing Christians commonly refer to the week before Easter as Holy Week, which in Western Christianity begins on Palm Sunday (marking the entrance of Jesus in Jerusalem), includes Spy Wednesday (on whic ...
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Julian Calendar
The Julian calendar, proposed by Roman consul Julius Caesar in 46 BC, was a reform of the Roman calendar. It took effect on , by edict. It was designed with the aid of Greek mathematicians and astronomers such as Sosigenes of Alexandria. The calendar became the predominant calendar in the Roman Empire and subsequently most of the Western world for more than 1,600 years until 1582, when Pope Gregory XIII promulgated a minor modification to reduce the average length of the year from 365.25 days to 365.2425 days and thus corrected the Julian calendar's drift against the solar year. Worldwide adoption of this revised calendar, which became known as the Gregorian calendar, took place over the subsequent centuries, first in Catholic countries and subsequently in Protestant countries of the Western Christian world. The Julian calendar is still used in parts of the Eastern Orthodox Church and in parts of Oriental Orthodoxy as well as by the Berbers. The Julian calenda ...
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Metonic Cycle
The Metonic cycle or enneadecaeteris (from grc, ἐννεακαιδεκαετηρίς, from ἐννεακαίδεκα, "nineteen") is a period of almost exactly 19 years after which the lunar phases recur at the same time of the year. The recurrence is not perfect, and by precise observation the Metonic cycle defined as 235 lunar month, synodic months is just 2 hours, 4 minutes and 58 seconds longer than 19 tropical year, tropical years. Meton of Athens, in the 5th century BC, judged the cycle to be a whole number of days, 6,940. Using these whole numbers facilitates the construction of a lunisolar calendar. A tropical year is longer than 12 lunar months and shorter than 13 of them. The arithmetic identity 12×12 + 7×13 = 235 shows that a combination of 12 "short" years (12 months) and 7 "long" years (13 months) will be almost exactly equal to 19 solar years. Application in traditional calendars In the Babylonian calendar, Babylonian and Hebrew calendar, ...
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Calendario Pasquale
A 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. The most common type of pre-modern calendar was the lunisolar calendar, a lunar calendar that occasionally adds one intercalary month to remain synchronized with the solar year over the long term. Etymology The term ''calendar'' is taken from , the term for the first day of the month in the Roman calendar, related to the verb 'to call out', referring to the "calling" of the new moon when it was first se ...
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Hebrew Calendar
The Hebrew calendar ( he, הַלּוּחַ הָעִבְרִי, translit=HaLuah HaIvri), also called the Jewish calendar, is a lunisolar calendar used today for Jewish religious observance, and as an official calendar of the state of Israel. It determines the dates for Jewish holidays and the appropriate Torah reading, public reading of Weekly Torah portion, Torah portions, ''yahrzeits'' (dates to commemorate the death of a relative), and daily Psalm readings, among many ceremonial uses. In Israel, it is used for religious purposes, provides a time frame for agriculture, and is an official calendar for civil holidays, alongside the Gregorian calendar. The present Hebrew calendar is the result of a process of development, including a Babylonian calendar, Babylonian influence. Until the Tannaitic period (approximately 10–220 Common Era, CE), the calendar employed a new lunar phase, crescent moon, with an Intercalation (timekeeping), additional month normally added every two or ...
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Paschal Full Moon
An ecclesiastical full moon is formally the 14th day of the ecclesiastical lunar month (an ecclesiastical moon) in an ecclesiastical lunar calendar. The ecclesiastical lunar calendar spans the year with lunar months of 30 and 29 days which are intended to approximate the observed phases of the Moon. Since a true synodic month has a length that can vary from about 29.27 to 29.83 days, the moment of astronomical opposition tends to be roughly 14.75 days after the previous conjunction of the Sun and Moon (the new moon). The ecclesiastical full moons of the Gregorian lunar calendar tend to agree with the dates of astronomical opposition, referred to a day beginning at midnight at 0 degrees longitude, to within a day or so. However, the astronomical opposition happens at a single moment for the entire Earth: The hour and day at which the opposition is measured as having taken place will vary with longitude. In the ecclesiastical calendar, the 14th day of the lunar month, reckoned ...
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Anno Domini
The terms (AD) and before Christ (BC) are used to label or number years in the Julian and Gregorian calendars. The term is Medieval Latin and means 'in the year of the Lord', but is often presented using "our Lord" instead of "the Lord", taken from the full original phrase "''anno Domini nostri Jesu Christi''", which translates to 'in the year of our Lord Jesus Christ'. The form "BC" is specific to English and equivalent abbreviations are used in other languages: the Latin form is but is rarely seen. This calendar era is based on the traditionally reckoned year of the conception or birth of Jesus, ''AD'' counting years from the start of this epoch and ''BC'' denoting years before the start of the era. There is no year zero in this scheme; thus ''the year AD 1 immediately follows the year 1 BC''. This dating system was devised in 525 by Dionysius Exiguus, but was not widely used until the 9th century. Traditionally, English follows Latin usage by placing the "AD" abbr ...
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Gregorian Reform Of The Calendar
The Gregorian calendar is the calendar used in most parts of the world. It was introduced in October 1582 by Pope Gregory XIII 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. The rule for leap years is: There were two reasons to establish the Gregorian calendar. First, the Julian calendar assumed incorrectly that the average solar year is exactly 365.25 days long, an overestimate of a little under one day per century, and thus has a leap year every four years without exception. The Gregorian reform shortened the average (calendar) year by 0.0075 days to stop the drift of the calendar with respect to the equinoxes.See Wikisource English translation of the (Latin) 1582 papal bull ''Inter gravissimas''. Second, in ...
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Gregorian Calendar
The Gregorian calendar is the calendar used in most parts of the world. It was introduced in October 1582 by Pope Gregory XIII 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. The rule for leap years is: There were two reasons to establish the Gregorian calendar. First, the Julian calendar assumed incorrectly that the average solar year is exactly 365.25 days long, an overestimate of a little under one day per century, and thus has a leap year every four years without exception. The Gregorian reform shortened the average (calendar) year by 0.0075 days to stop the drift of the calendar with respect to the equinoxes.See Wikisource English translation of the (Latin) 1582 papal bull '' Inter gravissimas''. Second, ...
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Moveable Feast
A moveable feast is an observance in a Christian liturgical calendar which occurs on different dates in different years.John Ayto ''Oxford Dictionary of English Idioms'' 2010 p123 019954378X "a movable feast an event which takes place at no regular time. In a religious context a movable feast is a feast day (especially Easter Day and the other Christian holy days whose dates are related to it) which does not occur on the same calendar date each year." Spring paschal feasts Often considered the most important Christian observance, Spring paschal feasts are a fixed number of days before or after Easter Sunday, which Computus, varies by 35 days since it depends partly on the Lunisolar calendar, phase of the moon and must be Computus, computed each year. In the Hebrew calendar, the new moon of Aviv, spring, is fixed as the Lunar New Year#Middle East/West Asia, Lunar New Year, and the month is called Nisan. The 14 of Nisan is the paschal full moon, the day of the Pesach seder, a ri ...
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Intercalation (timekeeping)
Intercalation or embolism in timekeeping is the insertion of a leap day, week, or month into some calendar years to make the calendar follow the seasons or moon phases. Lunisolar calendars may require intercalations of both days and months. Solar calendars The solar or tropical year does not have a whole number of days (it is about 365.24 days), but a calendar year must have a whole number of days. The most common way to reconcile the two is to vary the number of days in the calendar year. In solar calendars, this is done by adding to a common year of 365 days, an extra day ("leap day" or "intercalary day") about every four years, causing a leap year to have 366 days ( Julian, Gregorian and Indian national calendars). The Decree of Canopus, which was issued by the pharaoh Ptolemy III Euergetes of Ancient Egypt in 239 BCE, decreed a solar leap day system; an Egyptian leap year was not adopted until 25 BC, when the Roman Emperor Augustus successfully instituted a reformed A ...
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The Reckoning Of Time
''The Reckoning of Time'' ( la, De temporum ratione) is an Anglo-Saxon era treatise written in Medieval Latin by the Northumbrian monk Bede in 725. The treatise includes an introduction to the traditional ancient and medieval view of the cosmos, including an explanation of how the spherical Earth influenced the changing length of daylight, of how the seasonal motion of the Sun and Moon influenced the changing appearance of the new moon at evening twilight, and a quantitative relation between the changes of the tides at a given place and the daily motion of the Moon. ''The Reckoning of Time'' describes the principal ancient calendars, including those of the Hebrews, the Egyptians, the Romans, the Greeks, and the Anglo-Saxons.Wallis (2004:41-54;281–287 The focus of ' was calculation of the date of Easter, for which Bede described the method developed by Dionysius Exiguus. ' also gave instructions for calculating the date of the Easter full moon, for calculating the motion of ...
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