Paschal Full Moon
Encyclopedia
Notionally, the paschal full moon refers to the ecclesiastical
full moon
of the northern spring used in the determination of the date of Easter
. The name "paschal" is derived from "Pascha
", a transliteration of the Greek word, which is itself a transliteration of the Hebrew
pesach, both words meaning Passover
. The date of Easter is determined as the first Sunday after the paschal full moon. This full moon does not currently correspond directly to any astronomical
event, but is instead the 14th day of a lunar month, determined from tables. It may differ from the date of the actual full moon by up to two days. The use of tables instead of actual observations of the full moon is useful and necessary since the full moon may occur on different dates depending where one is in the world.
The calculations to determine the date of the paschal full moon are somewhat complex, but can be described briefly as follows: Nineteen civil calendar years are divided into 235 lunar months of 30 and 29 days each (the so-called "ecclesiastical moon".) The period of 19 years (the metonic cycle
) is used because it produces a set of civil calendar dates for the ecclesiastical moons that repeats every nineteen years while still providing a reasonable approximation to the astronomical facts. The first day of each of these lunar months is the ecclesiastical new moon
. Exactly one ecclesiastical new moon in each year falls on a date between March 8 and April 5, both inclusive. This begins the paschal lunar month for that year, and thirteen days later is the paschal full moon. Easter is the Sunday following the paschal full moon. In other words, Easter falls from one to seven days after the paschal full moon, so that if the paschal full moon is on Sunday, Easter is the following Sunday.
For a detailed discussion of the paschal computations, see Computus
.
and the one of Alexandria
, had begun to calculate their own periodic sequences of dates of paschal full moon, to be able to determine their own dates of Easter Sunday. The motivation for these experiments was a dissatisfaction with the Jewish calendars that Christians had hitherto relied on to fix the date of Easter. These Jewish calendars, according to their Christian critics, sometimes placed Nisan 14, the paschal full moon and the day of preparation for the Jewish Passover, before the spring equinox (see Easter
). The Christians who began the experiments with independent computations held that the paschal full moon should never precede the equinox.
The computational principles developed at Alexandria eventually became normative, but their reception was a centuries-long process during which Alexandrian Easter tables competed with other tables incorporating different arithmetical parameters. So for a period of several centuries the sequences of dates of the paschal full moon applied by different churches could show great differences (see Easter controversy
).
Ecclesiastical full moon
An ecclesiastical full moon is the fourteenth day of a lunar month 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...
full moon
Full moon
Full moon lunar phase that occurs when the Moon is on the opposite side of the Earth from the Sun. More precisely, a full moon occurs when the geocentric apparent longitudes of the Sun and Moon differ by 180 degrees; the Moon is then in opposition with the Sun.Lunar eclipses can only occur at...
of the northern spring used in the determination of the date of Easter
Easter
Easter is the central feast in the Christian liturgical year. According to the Canonical gospels, Jesus rose from the dead on the third day after his crucifixion. His resurrection is celebrated on Easter Day or Easter Sunday...
. The name "paschal" is derived from "Pascha
Pascha
Pascha may refer to:*Easter, central religious feast in the Christian liturgical year*Paskha , an Easter dish served in several Slavic countries*Paska , an Easter bread served in Ukraine...
", a transliteration of the Greek word, which is itself a transliteration of the Hebrew
Hebrew language
Hebrew is a Semitic language of the Afroasiatic language family. Culturally, is it considered by Jews and other religious groups as the language of the Jewish people, though other Jewish languages had originated among diaspora Jews, and the Hebrew language is also used by non-Jewish groups, such...
pesach, both words meaning Passover
Passover
Passover is a Jewish holiday and festival. It commemorates the story of the Exodus, in which the ancient Israelites were freed from slavery in Egypt...
. The date of Easter is determined as the first Sunday after the paschal full moon. This full moon does not currently correspond directly to any astronomical
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...
event, but is instead the 14th day of a lunar month, determined from tables. It may differ from the date of the actual full moon by up to two days. The use of tables instead of actual observations of the full moon is useful and necessary since the full moon may occur on different dates depending where one is in the world.
The calculations to determine the date of the paschal full moon are somewhat complex, but can be described briefly as follows: Nineteen civil calendar years are divided into 235 lunar months of 30 and 29 days each (the so-called "ecclesiastical moon".) The period of 19 years (the metonic cycle
Metonic cycle
In astronomy and calendar studies, the Metonic cycle or Enneadecaeteris is a period of very close to 19 years which is remarkable for being very nearly a common multiple of the solar year and the synodic month...
) is used because it produces a set of civil calendar dates for the ecclesiastical moons that repeats every nineteen years while still providing a reasonable approximation to the astronomical facts. The first day of each of these lunar months is the ecclesiastical new moon
Ecclesiastical new moon
An ecclesiastical new moon is the first day of a lunar month in an ecclesiastical lunar calendar. Such months have a whole number of days, 29 or 30, whereas true synodic months can vary from about 29.27 to 29.83 days in length. Medieval authors equated the ecclesiastical new moon with a new...
. Exactly one ecclesiastical new moon in each year falls on a date between March 8 and April 5, both inclusive. This begins the paschal lunar month for that year, and thirteen days later is the paschal full moon. Easter is the Sunday following the paschal full moon. In other words, Easter falls from one to seven days after the paschal full moon, so that if the paschal full moon is on Sunday, Easter is the following Sunday.
For a detailed discussion of the paschal computations, see Computus
Computus
Computus is the calculation of the date of Easter in the Christian calendar. The name has been used for this procedure since the early Middle Ages, as it was one of the most important computations of the age....
.
Easter tables
By the middle of the third century AD computists of some churches, among which were the Church of RomeRoman Catholic Church
The Catholic Church, also known as the Roman Catholic Church, is the world's largest Christian church, with over a billion members. Led by the Pope, it defines its mission as spreading the gospel of Jesus Christ, administering the sacraments and exercising charity...
and the one of Alexandria
Eastern Orthodox Church
The Orthodox Church, officially called the Orthodox Catholic Church and commonly referred to as the Eastern Orthodox Church, is the second largest Christian denomination in the world, with an estimated 300 million adherents mainly in the countries of Belarus, Bulgaria, Cyprus, Georgia, Greece,...
, had begun to calculate their own periodic sequences of dates of paschal full moon, to be able to determine their own dates of Easter Sunday. The motivation for these experiments was a dissatisfaction with the Jewish calendars that Christians had hitherto relied on to fix the date of Easter. These Jewish calendars, according to their Christian critics, sometimes placed Nisan 14, the paschal full moon and the day of preparation for the Jewish Passover, before the spring equinox (see Easter
Easter
Easter is the central feast in the Christian liturgical year. According to the Canonical gospels, Jesus rose from the dead on the third day after his crucifixion. His resurrection is celebrated on Easter Day or Easter Sunday...
). The Christians who began the experiments with independent computations held that the paschal full moon should never precede the equinox.
The computational principles developed at Alexandria eventually became normative, but their reception was a centuries-long process during which Alexandrian Easter tables competed with other tables incorporating different arithmetical parameters. So for a period of several centuries the sequences of dates of the paschal full moon applied by different churches could show great differences (see Easter controversy
Easter controversy
The Easter controversy is a series of controversies about the proper date to celebrate the Christian holiday of Easter. To date, there are four distinct historical phases of the dispute and the dispute has yet to be resolved...
).
See also
- Golden numbersGolden numbersA golden number is a number assigned to each year in sequence to indicate the year's position in a 19-year Metonic cycle. They are used in the computus and also in the Runic calendar. The golden number of any Julian or Gregorian calendar year can be calculated by dividing the year by 19, taking...
- Reform of the date of EasterReform of the date of EasterReform of the date of Easter has been proposed several times because the current system for determining the date of Easter is seen as presenting two significant problems:...
- Dionysius Exiguus' Easter tableDionysius Exiguus' Easter tableDionysius Exiguus's Easter table was constructed in the year 525 by Dionysius Exiguus for the years 532–626. He obtained it from an Easter table attributed to Patriarch Cyril of Alexandria for the years 437–531. The latter was constructed around the year 440 by means of extrapolation from an...